Modules

Top-level package for Fast Dash.

FastDash

Fast Dash app object containing automatically generated UI components and callbacks.

This is the primary Fast Dash data structure. Can be thought of as a wrapper around a flask WSGI application. It has in-built support for automated UI generation and sets all parameters required for Fast Dash app deployment.

Source code in fast_dash/fast_dash.py

class FastDash:
    """
    Fast Dash app object containing automatically generated UI components and callbacks.

    This is the primary Fast Dash data structure. Can be thought of as a wrapper around
    a flask WSGI application. It has in-built support for automated UI generation and
    sets all parameters required for Fast Dash app deployment.
    """

    def __init__(
        self,
        callback_fn,
        layout="sidebar",
        mosaic=None,
        inputs=None,
        outputs=None,
        output_labels="infer",
        title=None,
        title_image_path=None,
        subheader=None,
        github_url=None,
        linkedin_url=None,
        twitter_url=None,
        navbar=True,
        footer=True,
        loader="bars",
        branding=True,
        about=True,
        theme=None,
        update_live=False,
        port=8080,
        mode=None,
        minimal=False,
        disable_logs=False,
        scale_height=1,
        run_kwargs=dict(),
        **kwargs
    ):
        """
        Args:
            callback_fn (func): Python function that Fast Dash deploys. \
                This function guides the behavior of and interaction between input and output components.

            layout (str, optional): App layout style. Currently supports 'base' and 'sidebar'. Defaults to sidebar.

            mosaic (str): Mosaic array layout, if sidebar layout is selected.

            inputs (Fast component, list of Fast components, optional): Components to represent inputs of the callback function.\
                Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type \
                hints and default values. In the absence of type hints, default components are all `Text`.

            outputs (Fast component, list of Fast components, optional): Components to represent outputs of the callback function.\
                Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type hints.\
                In the absence of type hints, default components are all `Text`.

            output_labels(list of string labels or "infer" or None, optional): Labels given to the output components. If None, inputs are\
                set labeled integers starting at 1 (Output 1, Output 2, and so on). If "infer", labels are inferred from the function\
                signature. Defaults to infer.

            title (str, optional): Title given to the app. If `None`, function name (assumed to be in snake case)\
                is converted to title case. Defaults to None.

            title_image_path (str, optional): Path (local or URL) of the app title image. Defaults to None.

            subheader (str, optional): Subheader of the app, displayed below the title image and title\
                If `None`, Fast Dash tries to use the callback function's docstring instead. Defaults to None.

            github_url (str, optional): GitHub URL for branding. Displays a GitHub logo in the navbar, which takes users to the\
                specified URL. Defaults to None.

            linkedin_url (str, optional): LinkedIn URL for branding Displays a LinkedIn logo in the navbar, which takes users to the\
                specified URL. Defaults to None.

            twitter_url (str, optional): Twitter URL for branding. Displays a Twitter logo in the navbar, which takes users to the\
                specified URL. Defaults to None.

            navbar (bool, optional): Display navbar. Defaults to True.

            footer (bool, optional): Display footer. Defaults to True.

            loader (str or bool, optional): Type of loader to display when the app is loading. If `None`, no loader is displayed. \
                If `True`, a default loader is displayed. If `str`, the loader is set to the specified type. \

            branding (bool, optional): Display Fast Dash branding component in the footer. Defaults to True. \

            about (Union[str, bool], optional): App description to display on clicking the `About` button. If True, content is inferred from\
                the docstring of the callback function. If string, content is used directly as markdown. \
                `About` is hidden if False or None. Defaults to True.

            theme (str, optional): Apply theme to the app.All available themes can be found at https://bootswatch.com/. Defaults to JOURNAL. 

            update_live (bool, optional): Enable hot reloading. If the number of inputs is 0, this is set to True automatically. Defaults to False.

            port (int, optional): Port to which the app should be deployed. Defaults to 8080.

            mode (str, optional): Mode in which to launch the app. Acceptable options are `None`, `jupyterlab`, `inline`, 'external`.\
                Defaults to None.

            minimal (bool, optional): Display minimal version by hiding navbar, title, title image, subheader and footer. Defaults to False.

            disable_logs (bool, optional): Hide app logs. Sets logger level to `ERROR`. Defaults to False.

            scale_height (float, optional): Height of the app container is enlarged as a multiple of this. Defaults to 1.

            run_kwargs (dict, optional): All values from this variable are passed to Dash's `.run` method.
        """

        self.mode = mode
        self.disable_logs = disable_logs
        self.scale_height = scale_height
        self.port = port
        self.run_kwargs = run_kwargs
        self.run_kwargs.update(dict(port=port))
        self.kwargs = kwargs

        if self.disable_logs is True:
            log = logging.getLogger("werkzeug")
            log.setLevel(logging.ERROR)

        else:
            log = logging.getLogger("werkzeug")
            log.setLevel(logging.DEBUG)

        if title is None:
            title = re.sub("[^0-9a-zA-Z]+", " ", callback_fn.__name__).title()

        self.title = title

        self.title_image_path = title_image_path
        self.subtitle = (
            subheader
            if subheader is not None
            else _parse_docstring_as_markdown(
                callback_fn, title=self.title, get_short=True
            )
        )
        self.github_url = github_url
        self.linkedin_url = linkedin_url
        self.twitter_url = twitter_url
        self.navbar = navbar
        self.footer = footer
        self.loader = loader
        self.branding = branding
        self.about = about
        self.theme = theme or "JOURNAL"
        self.minimal = minimal

        # Define Flask server
        server = flask.Flask(__name__)
        external_stylesheets = [
            theme_mapper(self.theme),
            "https://use.fontawesome.com/releases/v5.9.0/css/all.css",
        ]

        source = dash.Dash
        self.app = source(
            __name__,
            external_stylesheets=external_stylesheets,
            server=server,
            **self.kwargs,
        )

        # Allow easier access to Dash server
        self.server = self.app.server
        self.callback = self.app.callback
        socketio = SocketIO(self.app.server)

        # Define other attributes
        self.callback_fn = callback_fn
        self.layout_pattern = layout
        self.mosaic = mosaic
        self.output_labels = output_labels

        # Initialize state indicators
        self.state_counter = 0

        if output_labels == "infer":
            self.output_labels = _infer_variable_names(callback_fn, upper_case=True)

        self.inputs = (
            _infer_input_components(callback_fn)
            if inputs is None
            else inputs if isinstance(inputs, list) else [inputs]
        )
        self.outputs = _infer_output_components(
            callback_fn, outputs, self.output_labels
        )
        self.update_live = (
            True
            if (isinstance(self.inputs, list) and len(self.inputs) == 0)
            else update_live
        )

        # Extract input tags
        self.input_tags = [inp.tag for inp in self.inputs]
        self.output_tags = [inp.tag for inp in self.outputs]

        # Assign IDs to components
        self.inputs_with_ids = _assign_ids_to_inputs(self.inputs, self.callback_fn)
        self.outputs_with_ids = _assign_ids_to_outputs(self.outputs, self.callback_fn)
        self.ack_mask = [
            False if (not hasattr(input_, "ack") or (input_.ack is None)) else True
            for input_ in self.inputs_with_ids
        ]

        # Default state of outputs
        self.output_state_default = [
            output_.placeholder if hasattr(output_, "placeholder") else None
            for output_ in self.outputs_with_ids
        ]
        self.output_state = self.output_state_default

        self.output_state_blank = [None for output_ in self.outputs_with_ids]
        self.latest_output_state = self.output_state_blank

        # Intialize layout
        self.app.title = self.title or ""
        self.set_layout()

        # Register callbacks
        self.register_callback_fn()
        self.add_streaming()

        # Keep track of the number of clicks
        self.submit_clicks = 0
        self.reset_clicks = 0
        self.app_initialized = False

    def run(self):
        self.app.run(**self.run_kwargs) if self.mode is None else self.app.run(
            jupyter_mode=self.mode, **self.run_kwargs
        )

    def run_server(self):
        self.app.run(
            **self.run_kwargs
        ) if self.mode is None else self.app.run(
            jupyter_mode=self.mode, **self.run_kwargs
        )

    def set_layout(self):
        if self.inputs is not None:
            input_groups = _make_input_groups(self.inputs_with_ids, self.update_live)

        if self.outputs is not None:
            output_groups = _make_output_groups(self.outputs_with_ids, self.update_live)

        layout_args = {
            "mosaic": self.mosaic,
            "inputs": input_groups,
            "outputs": output_groups,
            "title": self.title,
            "title_image_path": self.title_image_path,
            "subtitle": self.subtitle,
            "github_url": self.github_url,
            "linkedin_url": self.linkedin_url,
            "twitter_url": self.twitter_url,
            "navbar": self.navbar,
            "footer": self.footer,
            "loader": self.loader,
            "branding": self.branding,
            "about": self.about,
            "minimal": self.minimal,
            "scale_height": self.scale_height,
            "app": self,
        }

        if self.layout_pattern == "sidebar":
            app_layout = SidebarLayout(**layout_args)

        else:
            app_layout = BaseLayout(**layout_args)

        self.layout_object = app_layout
        notification_components = ["notification-container"]

        streaming_components = [c.id for c in self.outputs_with_ids]
        streaming_components.extend(notification_components)

        # Add responses of chat components if present
        chat_components = [c for c in self.outputs_with_ids if c.tag == "Chat"]

        for component in chat_components:
            [streaming_components.append(f"{component.id}_{i + 1}_response") for i in range(100)]

        self.app.layout = app_layout.generate_layout(stream_event_names=streaming_components)

    def register_callback_fn(self):

        self.app.clientside_callback(
            f"""
            function updateLoadingState(n_clicks) {{
                return {"true" if self.loader else "false"}; 
            }}
            """,
            Output("loading-overlay", "visible", allow_duplicate=True),
            Input("submit_inputs", "n_clicks"),
            prevent_initial_call=True,
        )

        @self.app.callback(
            [
                Output(
                    component_id=output_.id,
                    component_property=output_.component_property,
                )
                for output_ in self.outputs_with_ids
            ]
            + [Output("notification-container", "sendNotifications"), Output("loading-overlay", "visible")],
            [
                Input(
                    component_id=input_.id, component_property=input_.component_property
                )
                for input_ in self.inputs_with_ids
            ]
            + [
                Input(component_id="reset_inputs", component_property="n_clicks"),
                Input(component_id="submit_inputs", component_property="n_clicks"),
                State("socketio", "socketId"),
            ],
            running=[(Output("submit_inputs", "disabled"), True, False)],
            prevent_initial_callback=True,
            prevet_initial_call=True
        )
        def process_input(*args):
            if (
                ctx.triggered_id not in ["submit_inputs", "reset_inputs"]
                and self.update_live is False
            ):
                raise PreventUpdate

            default_notification = []
            self.state_counter += 1

            try:
                inputs = _transform_inputs(args[:-3], self.input_tags)

                if ctx.triggered_id == "submit_inputs" or (
                    self.update_live is True and None not in args
                ):
                    self.app_initialized = True

                    stream_handler_func = functools.partial(self.stream_handler, socket_id=args[-1])
                    with StreamContext(stream_handler_func):
                        output_state = self.callback_fn(*inputs)

                    if isinstance(output_state, tuple):
                        self.output_state = list(output_state)

                    else:
                        self.output_state = [output_state]

                    # Transform outputs to fit in the desired components
                    self.output_state = _transform_outputs(
                        self.output_state, self.output_tags, self.outputs_with_ids, self.state_counter
                    )

                    # Log the latest output state
                    self.latest_output_state = self.output_state

                    return self.output_state + [default_notification, False]

                elif ctx.triggered_id == "reset_inputs":
                    self.output_state = self.output_state_default
                    return self.output_state + [default_notification, False]

                elif self.app_initialized:
                    return self.output_state + [default_notification, False]

                else:
                    return self.output_state_default + [default_notification, False]

            except Exception as e:
                traceback.print_exc()
                notification = _get_error_notification_component(str(e))

                return self.output_state_default + [notification, False]

        @self.app.callback(
            [
                Output(
                    component_id=input_.ack.id,
                    component_property=input_.ack.component_property,
                )
                for input_ in self.inputs_with_ids
            ]
            + [Output("dummy-div", "children")],
            [
                Input(
                    component_id=input_.id, component_property=input_.component_property
                )
                for input_ in self.inputs_with_ids
            ]
            + [Input("dummy-div", "children")],
        )
        def process_ack_outputs(*args):
            ack_components = [
                ack if mask is True else None
                for mask, ack in zip(self.ack_mask, list(args)[:-1])
            ]
            return ack_components + [[]]

        # Set layout callbacks
        if not self.minimal:
            self.layout_object.callbacks(self)

    # Define a stream handler function
    def stream_handler(self, component_id, data, property=None, socket_id=None, notification=True):
        """A simple handler that prints to console and returns a response"""

        if notification:
            emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)
            return f"Notification: {data}"

        component = [c for c in self.outputs_with_ids if c.id == f"output_{component_id}"]

        if not component:
            raise ValueError(f"Component with id {component_id} not found in outputs.")

        component = component[0]
        component_id = component.id

        if component.tag == "Chat" and not property:
            raise ValueError("Argument 'property' must be specified for chat components. Allowed 'property' values are 'query' and 'response'.")

        if component.tag == "Chat" and property  not in ["query", "response"]:
            raise ValueError("Invalid 'property' value for chat component. Allowed 'property' values are 'query' and 'response'.")

        component_state_func = _get_transform_function(output=data, 
                                                       tag=component.tag, 
                                                       component_id=component.id, 
                                                       counter=self.state_counter,
                                                       partial_update=True)


        if component.tag == "Chat" and property == "query":

            # Add a new component to the chat response
            data = dict(query=data, response="")
            component_state = json.loads(to_json_plotly(component_state_func(data)))
            component.stream = True

            emit(component_id, {"value": component_state, "append": True}, namespace="/", to=socket_id)

        elif component.tag == "Chat" and property == "response":
            component_id = f"{component_id}_{self.state_counter}_response"

            emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)

        else:
            emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)

        return f"Received: {data}"


    def add_streaming(self):
        """Add streaming functionality to the app."""

        update_func = """
            function(payload, current_value) {
                if (!payload) {
                    return dash_clientside.no_update;
                }

                const { value, append } = payload;

                if (value === null || value === undefined) {
                    return dash_clientside.no_update;
                }

                let new_value;

                // Parse the incoming value if it's a string
                if (typeof value === 'string' && value !== '') {
                    try {
                        new_value = JSON.parse(value);
                    } catch (e) {
                        new_value = value;
                    }
                } else {
                    new_value = value;
                }

                // If append is true, combine with current value
                if (append) {
                    const current = current_value || [];
                    const current_array = Array.isArray(current) ? current : [current];

                    if (Array.isArray(new_value)) {
                        return [...new_value, ...current_array];
                    } else {
                        return [new_value, ...current_array];
                    }
                }

                return new_value;
            }
            """

        for component in self.outputs_with_ids:

            # All clientside callbacks
            self.app.clientside_callback(
                update_func,
                Output(component.id, component.component_property, allow_duplicate=True),
                Input("socketio", f"data-{component.id}"),
                State(component.id, component.component_property),
                prevent_initial_call=True,
            )

            if component.tag == "Chat":
                for i in range(100):
                    c_id = f"{component.id}_{i + 1}_response"
                    self.app.clientside_callback(
                            update_func,
                            Output(c_id, "children", allow_duplicate=True),
                            Input("socketio", f"data-{c_id}"),
                            State(c_id, "children"),
                            prevent_initial_call=True,
                        )

        component_id = "notification-container"
        component_property = "sendNotifications"
        self.app.clientside_callback(
                update_func,
                Output(component_id, component_property, allow_duplicate=True),
                Input("socketio", f"data-{component_id}"),
                State(component_id, component_property),
                prevent_initial_call=True,
            )

__init__(callback_fn, layout='sidebar', mosaic=None, inputs=None, outputs=None, output_labels='infer', title=None, title_image_path=None, subheader=None, github_url=None, linkedin_url=None, twitter_url=None, navbar=True, footer=True, loader='bars', branding=True, about=True, theme=None, update_live=False, port=8080, mode=None, minimal=False, disable_logs=False, scale_height=1, run_kwargs=dict(), kwargs)

Parameters:

Name	Type	Description	Default
callback_fn	func	Python function that Fast Dash deploys. This function guides the behavior of and interaction between input and output components.	required
layout	str	App layout style. Currently supports 'base' and 'sidebar'. Defaults to sidebar.	'sidebar'
mosaic	str	Mosaic array layout, if sidebar layout is selected.	None
inputs	Fast component, list of Fast components	Components to represent inputs of the callback function. Defaults to None. If None, Fast Dash attempts to infer the best components from callback function's type hints and default values. In the absence of type hints, default components are all Text.	None
outputs	Fast component, list of Fast components	Components to represent outputs of the callback function. Defaults to None. If None, Fast Dash attempts to infer the best components from callback function's type hints. In the absence of type hints, default components are all Text.	None
output_labels(list	of string labels or "infer" or None	Labels given to the output components. If None, inputs are set labeled integers starting at 1 (Output 1, Output 2, and so on). If "infer", labels are inferred from the function signature. Defaults to infer.	required
title	str	Title given to the app. If None, function name (assumed to be in snake case) is converted to title case. Defaults to None.	None
title_image_path	str	Path (local or URL) of the app title image. Defaults to None.	None
subheader	str	Subheader of the app, displayed below the title image and title If None, Fast Dash tries to use the callback function's docstring instead. Defaults to None.	None
github_url	str	GitHub URL for branding. Displays a GitHub logo in the navbar, which takes users to the specified URL. Defaults to None.	None
linkedin_url	str	LinkedIn URL for branding Displays a LinkedIn logo in the navbar, which takes users to the specified URL. Defaults to None.	None
twitter_url	str	Twitter URL for branding. Displays a Twitter logo in the navbar, which takes users to the specified URL. Defaults to None.	None
navbar	bool	Display navbar. Defaults to True.	True
footer	bool	Display footer. Defaults to True.	True
loader	str or bool	Type of loader to display when the app is loading. If None, no loader is displayed. If True, a default loader is displayed. If str, the loader is set to the specified type.	'bars'
branding	bool	Display Fast Dash branding component in the footer. Defaults to True.	True
about	Union[str, bool]	App description to display on clicking the About button. If True, content is inferred from the docstring of the callback function. If string, content is used directly as markdown. About is hidden if False or None. Defaults to True.	True
theme	str	Apply theme to the app.All available themes can be found at https://bootswatch.com/. Defaults to JOURNAL.	None
update_live	bool	Enable hot reloading. If the number of inputs is 0, this is set to True automatically. Defaults to False.	False
port	int	Port to which the app should be deployed. Defaults to 8080.	8080
mode	str	Mode in which to launch the app. Acceptable options are None, jupyterlab, inline, 'external`. Defaults to None.	None
minimal	bool	Display minimal version by hiding navbar, title, title image, subheader and footer. Defaults to False.	False
disable_logs	bool	Hide app logs. Sets logger level to ERROR. Defaults to False.	False
scale_height	float	Height of the app container is enlarged as a multiple of this. Defaults to 1.	1
run_kwargs	dict	All values from this variable are passed to Dash's .run method.	dict()

Source code in fast_dash/fast_dash.py

def __init__(
    self,
    callback_fn,
    layout="sidebar",
    mosaic=None,
    inputs=None,
    outputs=None,
    output_labels="infer",
    title=None,
    title_image_path=None,
    subheader=None,
    github_url=None,
    linkedin_url=None,
    twitter_url=None,
    navbar=True,
    footer=True,
    loader="bars",
    branding=True,
    about=True,
    theme=None,
    update_live=False,
    port=8080,
    mode=None,
    minimal=False,
    disable_logs=False,
    scale_height=1,
    run_kwargs=dict(),
    **kwargs
):
    """
    Args:
        callback_fn (func): Python function that Fast Dash deploys. \
            This function guides the behavior of and interaction between input and output components.

        layout (str, optional): App layout style. Currently supports 'base' and 'sidebar'. Defaults to sidebar.

        mosaic (str): Mosaic array layout, if sidebar layout is selected.

        inputs (Fast component, list of Fast components, optional): Components to represent inputs of the callback function.\
            Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type \
            hints and default values. In the absence of type hints, default components are all `Text`.

        outputs (Fast component, list of Fast components, optional): Components to represent outputs of the callback function.\
            Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type hints.\
            In the absence of type hints, default components are all `Text`.

        output_labels(list of string labels or "infer" or None, optional): Labels given to the output components. If None, inputs are\
            set labeled integers starting at 1 (Output 1, Output 2, and so on). If "infer", labels are inferred from the function\
            signature. Defaults to infer.

        title (str, optional): Title given to the app. If `None`, function name (assumed to be in snake case)\
            is converted to title case. Defaults to None.

        title_image_path (str, optional): Path (local or URL) of the app title image. Defaults to None.

        subheader (str, optional): Subheader of the app, displayed below the title image and title\
            If `None`, Fast Dash tries to use the callback function's docstring instead. Defaults to None.

        github_url (str, optional): GitHub URL for branding. Displays a GitHub logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        linkedin_url (str, optional): LinkedIn URL for branding Displays a LinkedIn logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        twitter_url (str, optional): Twitter URL for branding. Displays a Twitter logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        navbar (bool, optional): Display navbar. Defaults to True.

        footer (bool, optional): Display footer. Defaults to True.

        loader (str or bool, optional): Type of loader to display when the app is loading. If `None`, no loader is displayed. \
            If `True`, a default loader is displayed. If `str`, the loader is set to the specified type. \

        branding (bool, optional): Display Fast Dash branding component in the footer. Defaults to True. \

        about (Union[str, bool], optional): App description to display on clicking the `About` button. If True, content is inferred from\
            the docstring of the callback function. If string, content is used directly as markdown. \
            `About` is hidden if False or None. Defaults to True.

        theme (str, optional): Apply theme to the app.All available themes can be found at https://bootswatch.com/. Defaults to JOURNAL. 

        update_live (bool, optional): Enable hot reloading. If the number of inputs is 0, this is set to True automatically. Defaults to False.

        port (int, optional): Port to which the app should be deployed. Defaults to 8080.

        mode (str, optional): Mode in which to launch the app. Acceptable options are `None`, `jupyterlab`, `inline`, 'external`.\
            Defaults to None.

        minimal (bool, optional): Display minimal version by hiding navbar, title, title image, subheader and footer. Defaults to False.

        disable_logs (bool, optional): Hide app logs. Sets logger level to `ERROR`. Defaults to False.

        scale_height (float, optional): Height of the app container is enlarged as a multiple of this. Defaults to 1.

        run_kwargs (dict, optional): All values from this variable are passed to Dash's `.run` method.
    """

    self.mode = mode
    self.disable_logs = disable_logs
    self.scale_height = scale_height
    self.port = port
    self.run_kwargs = run_kwargs
    self.run_kwargs.update(dict(port=port))
    self.kwargs = kwargs

    if self.disable_logs is True:
        log = logging.getLogger("werkzeug")
        log.setLevel(logging.ERROR)

    else:
        log = logging.getLogger("werkzeug")
        log.setLevel(logging.DEBUG)

    if title is None:
        title = re.sub("[^0-9a-zA-Z]+", " ", callback_fn.__name__).title()

    self.title = title

    self.title_image_path = title_image_path
    self.subtitle = (
        subheader
        if subheader is not None
        else _parse_docstring_as_markdown(
            callback_fn, title=self.title, get_short=True
        )
    )
    self.github_url = github_url
    self.linkedin_url = linkedin_url
    self.twitter_url = twitter_url
    self.navbar = navbar
    self.footer = footer
    self.loader = loader
    self.branding = branding
    self.about = about
    self.theme = theme or "JOURNAL"
    self.minimal = minimal

    # Define Flask server
    server = flask.Flask(__name__)
    external_stylesheets = [
        theme_mapper(self.theme),
        "https://use.fontawesome.com/releases/v5.9.0/css/all.css",
    ]

    source = dash.Dash
    self.app = source(
        __name__,
        external_stylesheets=external_stylesheets,
        server=server,
        **self.kwargs,
    )

    # Allow easier access to Dash server
    self.server = self.app.server
    self.callback = self.app.callback
    socketio = SocketIO(self.app.server)

    # Define other attributes
    self.callback_fn = callback_fn
    self.layout_pattern = layout
    self.mosaic = mosaic
    self.output_labels = output_labels

    # Initialize state indicators
    self.state_counter = 0

    if output_labels == "infer":
        self.output_labels = _infer_variable_names(callback_fn, upper_case=True)

    self.inputs = (
        _infer_input_components(callback_fn)
        if inputs is None
        else inputs if isinstance(inputs, list) else [inputs]
    )
    self.outputs = _infer_output_components(
        callback_fn, outputs, self.output_labels
    )
    self.update_live = (
        True
        if (isinstance(self.inputs, list) and len(self.inputs) == 0)
        else update_live
    )

    # Extract input tags
    self.input_tags = [inp.tag for inp in self.inputs]
    self.output_tags = [inp.tag for inp in self.outputs]

    # Assign IDs to components
    self.inputs_with_ids = _assign_ids_to_inputs(self.inputs, self.callback_fn)
    self.outputs_with_ids = _assign_ids_to_outputs(self.outputs, self.callback_fn)
    self.ack_mask = [
        False if (not hasattr(input_, "ack") or (input_.ack is None)) else True
        for input_ in self.inputs_with_ids
    ]

    # Default state of outputs
    self.output_state_default = [
        output_.placeholder if hasattr(output_, "placeholder") else None
        for output_ in self.outputs_with_ids
    ]
    self.output_state = self.output_state_default

    self.output_state_blank = [None for output_ in self.outputs_with_ids]
    self.latest_output_state = self.output_state_blank

    # Intialize layout
    self.app.title = self.title or ""
    self.set_layout()

    # Register callbacks
    self.register_callback_fn()
    self.add_streaming()

    # Keep track of the number of clicks
    self.submit_clicks = 0
    self.reset_clicks = 0
    self.app_initialized = False

add_streaming()

Add streaming functionality to the app.

Source code in fast_dash/fast_dash.py

def add_streaming(self):
    """Add streaming functionality to the app."""

    update_func = """
        function(payload, current_value) {
            if (!payload) {
                return dash_clientside.no_update;
            }

            const { value, append } = payload;

            if (value === null || value === undefined) {
                return dash_clientside.no_update;
            }

            let new_value;

            // Parse the incoming value if it's a string
            if (typeof value === 'string' && value !== '') {
                try {
                    new_value = JSON.parse(value);
                } catch (e) {
                    new_value = value;
                }
            } else {
                new_value = value;
            }

            // If append is true, combine with current value
            if (append) {
                const current = current_value || [];
                const current_array = Array.isArray(current) ? current : [current];

                if (Array.isArray(new_value)) {
                    return [...new_value, ...current_array];
                } else {
                    return [new_value, ...current_array];
                }
            }

            return new_value;
        }
        """

    for component in self.outputs_with_ids:

        # All clientside callbacks
        self.app.clientside_callback(
            update_func,
            Output(component.id, component.component_property, allow_duplicate=True),
            Input("socketio", f"data-{component.id}"),
            State(component.id, component.component_property),
            prevent_initial_call=True,
        )

        if component.tag == "Chat":
            for i in range(100):
                c_id = f"{component.id}_{i + 1}_response"
                self.app.clientside_callback(
                        update_func,
                        Output(c_id, "children", allow_duplicate=True),
                        Input("socketio", f"data-{c_id}"),
                        State(c_id, "children"),
                        prevent_initial_call=True,
                    )

    component_id = "notification-container"
    component_property = "sendNotifications"
    self.app.clientside_callback(
            update_func,
            Output(component_id, component_property, allow_duplicate=True),
            Input("socketio", f"data-{component_id}"),
            State(component_id, component_property),
            prevent_initial_call=True,
        )

stream_handler(component_id, data, property=None, socket_id=None, notification=True)

A simple handler that prints to console and returns a response

Source code in fast_dash/fast_dash.py

def stream_handler(self, component_id, data, property=None, socket_id=None, notification=True):
    """A simple handler that prints to console and returns a response"""

    if notification:
        emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)
        return f"Notification: {data}"

    component = [c for c in self.outputs_with_ids if c.id == f"output_{component_id}"]

    if not component:
        raise ValueError(f"Component with id {component_id} not found in outputs.")

    component = component[0]
    component_id = component.id

    if component.tag == "Chat" and not property:
        raise ValueError("Argument 'property' must be specified for chat components. Allowed 'property' values are 'query' and 'response'.")

    if component.tag == "Chat" and property  not in ["query", "response"]:
        raise ValueError("Invalid 'property' value for chat component. Allowed 'property' values are 'query' and 'response'.")

    component_state_func = _get_transform_function(output=data, 
                                                   tag=component.tag, 
                                                   component_id=component.id, 
                                                   counter=self.state_counter,
                                                   partial_update=True)


    if component.tag == "Chat" and property == "query":

        # Add a new component to the chat response
        data = dict(query=data, response="")
        component_state = json.loads(to_json_plotly(component_state_func(data)))
        component.stream = True

        emit(component_id, {"value": component_state, "append": True}, namespace="/", to=socket_id)

    elif component.tag == "Chat" and property == "response":
        component_id = f"{component_id}_{self.state_counter}_response"

        emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)

    else:
        emit(component_id, {"value": data, "append": False}, namespace="/", to=socket_id)

    return f"Received: {data}"

Fastify(component, component_property, ack=None, placeholder=None, label_=None, tag=None, stream=False, args, kwargs)

Modify a Dash component into a FastComponent.

Parameters:

Name	Type	Description	Default
component	Dash component	Dash component that needs to be modified	required
component_property	str	Component property that's assigned the input or output values	required
ack	Dash component	Dash component that's displayed as an acknowledgement of the original component	None
placeholder	str	Placeholder value of the component.	None
label_	str	Component title.	None
tag	str	Optional tag applied to the component.	None

Returns:

Type	Description
	Fast component: Dash component modified to make it compatible with Fast Dash.

Source code in fast_dash/utils.py

def Fastify(component, component_property, ack=None, placeholder=None, label_=None, tag=None, stream=False, *args, **kwargs):
    """
    Modify a Dash component into a FastComponent.

    Args:
        component (Dash component): Dash component that needs to be modified
        component_property (str): Component property that's assigned the input or output values
        ack (Dash component, optional): Dash component that's displayed as an acknowledgement of the original component
        placeholder (str, optional): Placeholder value of the component.
        label_ (str, optional): Component title.
        tag (str, optional): Optional tag applied to the component.

    Returns:
        Fast component: Dash component modified to make it compatible with Fast Dash.
    """

    class FastComponent(type(component)):
        def __init__(self, component, component_property, ack=ack, placeholder=placeholder, label_=label_, tag=tag, stream=stream, *args, **kwargs):

            self.component = component
            self.component_property = component_property
            self.ack = ack
            self.label_ = label_
            self.placeholder = placeholder
            self.tag = tag
            self.stream = stream

            # Copy normal attributes
            for attr_name, attr_value in vars(component).items():
                setattr(self, attr_name, attr_value)

            # Copy the __doc__ attribute
            self.__doc__ = component.__doc__

            for key, value in kwargs.items():
                setattr(self, key, value)

        def __call__(self, **kwargs):            
            self_copy = copy.deepcopy(self)
            for key, value in kwargs.items():
                setattr(self_copy, key, value)

            return self_copy

    return FastComponent(component, component_property, ack=ack, placeholder=placeholder, label_=label_, tag=tag, stream=stream)

fastdash(_callback_fn=None, *, layout='sidebar', mosaic=None, inputs=None, outputs=None, output_labels='infer', title=None, title_image_path=None, subheader=None, github_url=None, linkedin_url=None, twitter_url=None, navbar=True, footer=True, loader='bars', branding=True, about=True, theme=None, update_live=False, port=8080, mode=None, minimal=False, disable_logs=False, scale_height=1, run_kwargs=dict(), kwargs)

Function decorator / wrapper for Fast Dash.

Parameters:

Name	Type	Description	Default
callback_fn	func	Python function that Fast Dash deploys. This function guides the behavior of and interaction between input and output components.	required
layout	str	App layout style. Currently supports 'base' and 'sidebar'. Defaults to sidebar.	'sidebar'
mosaic	str	Mosaic array layout, if sidebar layout is selected.	None
inputs	Fast component, list of Fast components	Components to represent inputs of the callback function. Defaults to None. If None, Fast Dash attempts to infer the best components from callback function's type hints and default values. In the absence of type hints, default components are all Text.	None
outputs	Fast component, list of Fast components	Components to represent outputs of the callback function. Defaults to None. If None, Fast Dash attempts to infer the best components from callback function's type hints. In the absence of type hints, default components are all Text.	None
output_labels(list	of string labels or "infer" or None	Labels given to the output components. If None, inputs are set labeled integers starting at 1 (Output 1, Output 2, and so on). If "infer", labels are inferred from the function signature. Defaults to infer.	required
title	str	Title given to the app. If None, function name (assumed to be in snake case) is converted to title case. Defaults to None.	None
title_image_path	str	Path (local or URL) of the app title image. Defaults to None.	None
subheader	str	Subheader of the app, displayed below the title image and title If None, Fast Dash tries to use the callback function's docstring instead. Defaults to None.	None
github_url	str	GitHub URL for branding. Displays a GitHub logo in the navbar, which takes users to the specified URL. Defaults to None.	None
linkedin_url	str	LinkedIn URL for branding Displays a LinkedIn logo in the navbar, which takes users to the specified URL. Defaults to None.	None
twitter_url	str	Twitter URL for branding. Displays a Twitter logo in the navbar, which takes users to the specified URL. Defaults to None.	None
navbar	bool	Display navbar. Defaults to True.	True
footer	bool	Display footer. Defaults to True.	True
loader	str or bool	Type of loader to display when the app is loading. If None, no loader is displayed. If True, a default loader is displayed. If str, the loader is set to the specified type.	'bars'
branding	bool	Display Fast Dash branding component in the footer. Defaults to True.	True
about	Union[str, bool]	App description to display on clicking the About button. If True, content is inferred from the docstring of the callback function. If string, content is used directly as markdown. About is hidden if False or None. Defaults to True.	True
theme	str	Apply theme to the app.All available themes can be found at https://bootswatch.com/. Defaults to JOURNAL.	None
update_live	bool	Enable hot reloading. If the number of inputs is 0, this is set to True automatically. Defaults to False.	False
port	int	Port to which the app should be deployed. Defaults to 8080.	8080
mode	str	Mode in which to launch the app. Acceptable options are None, jupyterlab, inline, 'external`. Defaults to None.	None
minimal	bool	Display minimal version by hiding navbar, title, title image, subheader and footer. Defaults to False.	False
disable_logs	bool	Hide app logs. Sets logger level to ERROR. Defaults to False.	False
scale_height	float	Height of the app container is enlarged as a multiple of this. Defaults to 1.	1
run_kwargs	dict	All values from this variable are passed to Dash's .run method.	dict()

Source code in fast_dash/fast_dash.py

def fastdash(
    _callback_fn=None,
    *,
    layout="sidebar",
    mosaic=None,
    inputs=None,
    outputs=None,
    output_labels="infer",
    title=None,
    title_image_path=None,
    subheader=None,
    github_url=None,
    linkedin_url=None,
    twitter_url=None,
    navbar=True,
    footer=True,
    loader="bars",
    branding=True,
    about=True,
    theme=None,
    update_live=False,
    port=8080,
    mode=None,
    minimal=False,
    disable_logs=False,
    scale_height=1,
    run_kwargs=dict(),
    **kwargs
):
    """
    Function decorator / wrapper for Fast Dash.

    Args:
        callback_fn (func): Python function that Fast Dash deploys. \
            This function guides the behavior of and interaction between input and output components.

        layout (str, optional): App layout style. Currently supports 'base' and 'sidebar'. Defaults to sidebar.

        mosaic (str): Mosaic array layout, if sidebar layout is selected.

        inputs (Fast component, list of Fast components, optional): Components to represent inputs of the callback function.\
            Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type \
            hints and default values. In the absence of type hints, default components are all `Text`.

        outputs (Fast component, list of Fast components, optional): Components to represent outputs of the callback function.\
            Defaults to None. If `None`, Fast Dash attempts to infer the best components from callback function's type hints.\
            In the absence of type hints, default components are all `Text`.

        output_labels(list of string labels or "infer" or None, optional): Labels given to the output components. If None, inputs are\
            set labeled integers starting at 1 (Output 1, Output 2, and so on). If "infer", labels are inferred from the function\
            signature. Defaults to infer.

        title (str, optional): Title given to the app. If `None`, function name (assumed to be in snake case)\
            is converted to title case. Defaults to None.

        title_image_path (str, optional): Path (local or URL) of the app title image. Defaults to None.

        subheader (str, optional): Subheader of the app, displayed below the title image and title\
            If `None`, Fast Dash tries to use the callback function's docstring instead. Defaults to None.


        github_url (str, optional): GitHub URL for branding. Displays a GitHub logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        linkedin_url (str, optional): LinkedIn URL for branding Displays a LinkedIn logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        twitter_url (str, optional): Twitter URL for branding. Displays a Twitter logo in the navbar, which takes users to the\
            specified URL. Defaults to None.

        navbar (bool, optional): Display navbar. Defaults to True.

        footer (bool, optional): Display footer. Defaults to True.

        loader (str or bool, optional): Type of loader to display when the app is loading. If `None`, no loader is displayed. \
                If `True`, a default loader is displayed. If `str`, the loader is set to the specified type. \

        branding (bool, optional): Display Fast Dash branding component in the footer. Defaults to True. \

        about (Union[str, bool], optional): App description to display on clicking the `About` button. If True, content is inferred from\
            the docstring of the callback function. If string, content is used directly as markdown. \
            `About` is hidden if False or None. Defaults to True.

        theme (str, optional): Apply theme to the app.All available themes can be found at https://bootswatch.com/. Defaults to JOURNAL. 

        update_live (bool, optional): Enable hot reloading. If the number of inputs is 0, this is set to True automatically. Defaults to False.

        port (int, optional): Port to which the app should be deployed. Defaults to 8080.

        mode (str, optional): Mode in which to launch the app. Acceptable options are `None`, `jupyterlab`, `inline`, 'external`.\
            Defaults to None.

        minimal (bool, optional): Display minimal version by hiding navbar, title, title image, subheader and footer. Defaults to False.

        disable_logs (bool, optional): Hide app logs. Sets logger level to `ERROR`. Defaults to False.

        scale_height (float, optional): Height of the app container is enlarged as a multiple of this. Defaults to 1.

        run_kwargs (dict, optional): All values from this variable are passed to Dash's `.run` method.
        """

    def decorator_fastdash(callback_fn):
        "Decorator for callback_fn"

        @functools.wraps(callback_fn)
        def wrapper_fastdash(**kwargs):
            app = FastDash(callback_fn=callback_fn, **kwargs)
            app.run()
            return callback_fn

        return wrapper_fastdash(
            layout=layout,
            mosaic=mosaic,
            inputs=inputs,
            outputs=outputs,
            output_labels=output_labels,
            title=title,
            title_image_path=title_image_path,
            subheader=subheader,
            github_url=github_url,
            linkedin_url=linkedin_url,
            twitter_url=twitter_url,
            navbar=navbar,
            footer=footer,
            loader=loader,
            branding=branding,
            about=about,
            theme=theme,
            update_live=update_live,
            mode=mode,
            port=port,
            minimal=minimal,
            disable_logs=disable_logs,
            scale_height=scale_height,
            run_kwargs=run_kwargs,
            **kwargs
        )

    # If the decorator is called with arguments
    if _callback_fn is None:
        return decorator_fastdash
    # If the decorator is called without arguments. Use default input and output values
    else:
        return decorator_fastdash(_callback_fn)