Function _prepare_response

dash/_callback.py:581–654

Prepare the response object based on the callback output.

(
    output_value,
    output_spec,
    multi,
    response: CallbackExecutionResponse,
    callback_ctx,
    app,
    original_packages,
    background,
    has_update,
    has_output,
    output,
    callback_id,
    allow_dynamic_callbacks,
)

# pylint: disable=too-many-branches
def _prepare_response(
    output_value,
    output_spec,
    multi,
    response: CallbackExecutionResponse,
    callback_ctx,
    app,
    original_packages,
    background,
    has_update,
    has_output,
    output,
    callback_id,
    allow_dynamic_callbacks,
):
    """Prepare the response object based on the callback output."""
    component_ids: dict = collections.defaultdict(dict)

    if has_output:
        if not multi:
            output_value, output_spec = [output_value], [output_spec]
            flat_output_values = output_value
        else:
            if isinstance(output_value, (list, tuple)):
                # For multi-output, allow top-level collection to be
                # list or tuple
                output_value = list(output_value)
            if NoUpdate.is_no_update(output_value):
                flat_output_values = [output_value]
            else:
                # Flatten grouping and validate grouping structure
                flat_output_values = flatten_grouping(output_value, output)

        if not NoUpdate.is_no_update(output_value):
            _validate.validate_multi_return(
                output_spec, flat_output_values, callback_id
            )

        for val, spec in zip(flat_output_values, output_spec):
            if NoUpdate.is_no_update(val):
                continue
            for vali, speci in (
                zip(val, spec) if isinstance(spec, list) else [[val, spec]]  # type: ignore[reportArgumentType]
            ):
                if not NoUpdate.is_no_update(vali):
                    has_update = True
                    id_str = stringify_id(speci["id"])
                    prop = clean_property_name(speci["property"])
                    component_ids[id_str][prop] = vali

    else:
        if output_value is not None:
            raise InvalidCallbackReturnValue(
                f"No-output callback received return value: {output_value}"
            )

    if not background:
        has_update = _set_side_update(callback_ctx, response) or has_output