324 lines
10 KiB
Python
324 lines
10 KiB
Python
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import functools
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import warnings
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import json
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import contextvars
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import typing
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import flask
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from . import exceptions
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from ._utils import AttributeDict, stringify_id
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context_value = contextvars.ContextVar("callback_context")
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context_value.set({})
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def has_context(func):
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@functools.wraps(func)
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def assert_context(*args, **kwargs):
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if not context_value.get():
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raise exceptions.MissingCallbackContextException(
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f"dash.callback_context.{getattr(func, '__name__')} is only available from a callback!"
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)
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return func(*args, **kwargs)
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return assert_context
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def _get_context_value():
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return context_value.get()
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def _get_from_context(key, default):
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return getattr(_get_context_value(), key, default)
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class FalsyList(list):
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def __bool__(self):
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# for Python 3
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return False
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def __nonzero__(self):
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# for Python 2
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return False
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falsy_triggered = FalsyList([{"prop_id": ".", "value": None}])
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# pylint: disable=no-init
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class CallbackContext:
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@property
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@has_context
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def inputs(self):
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return getattr(_get_context_value(), "input_values", {})
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@property
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@has_context
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def states(self):
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return getattr(_get_context_value(), "state_values", {})
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@property
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@has_context
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def triggered(self):
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"""
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Returns a list of all the Input props that changed and caused the callback to execute. It is empty when the
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callback is called on initial load, unless an Input prop got its value from another initial callback.
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Callbacks triggered by user actions typically have one item in triggered, unless the same action changes
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two props at once or the callback has several Input props that are all modified by another callback based on
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a single user action.
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Example: To get the id of the component that triggered the callback:
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`component_id = ctx.triggered[0]['prop_id'].split('.')[0]`
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Example: To detect initial call, empty triggered is not really empty, it's falsy so that you can use:
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`if ctx.triggered:`
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"""
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# For backward compatibility: previously `triggered` always had a
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# value - to avoid breaking existing apps, add a dummy item but
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# make the list still look falsy. So `if ctx.triggered` will make it
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# look empty, but you can still do `triggered[0]["prop_id"].split(".")`
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return getattr(_get_context_value(), "triggered_inputs", []) or falsy_triggered
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@property
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@has_context
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def triggered_prop_ids(self):
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"""
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Returns a dictionary of all the Input props that changed and caused the callback to execute. It is empty when
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the callback is called on initial load, unless an Input prop got its value from another initial callback.
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Callbacks triggered by user actions typically have one item in triggered, unless the same action changes
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two props at once or the callback has several Input props that are all modified by another callback based
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on a single user action.
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triggered_prop_ids (dict):
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- keys (str) : the triggered "prop_id" composed of "component_id.component_property"
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- values (str or dict): the id of the component that triggered the callback. Will be the dict id for pattern matching callbacks
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Example - regular callback
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{"btn-1.n_clicks": "btn-1"}
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Example - pattern matching callbacks:
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{'{"index":0,"type":"filter-dropdown"}.value': {"index":0,"type":"filter-dropdown"}}
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Example usage:
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`if "btn-1.n_clicks" in ctx.triggered_prop_ids:
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do_something()`
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"""
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triggered = getattr(_get_context_value(), "triggered_inputs", [])
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ids = AttributeDict({})
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for item in triggered:
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component_id, _, _ = item["prop_id"].rpartition(".")
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ids[item["prop_id"]] = component_id
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if component_id.startswith("{"):
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ids[item["prop_id"]] = AttributeDict(json.loads(component_id))
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return ids
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@property
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@has_context
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def triggered_id(self):
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"""
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Returns the component id (str or dict) of the Input component that triggered the callback.
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Note - use `triggered_prop_ids` if you need both the component id and the prop that triggered the callback or if
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multiple Inputs triggered the callback.
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Example usage:
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`if "btn-1" == ctx.triggered_id:
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do_something()`
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"""
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component_id = None
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if self.triggered:
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prop_id = self.triggered_prop_ids.first()
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component_id = self.triggered_prop_ids[prop_id]
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return component_id
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@property
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@has_context
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def args_grouping(self):
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"""
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args_grouping is a dict of the inputs used with flexible callback signatures. The keys are the variable names
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and the values are dictionaries containing:
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- “id”: (string or dict) the component id. If it’s a pattern matching id, it will be a dict.
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- “id_str”: (str) for pattern matching ids, it’s the stringified dict id with no white spaces.
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- “property”: (str) The component property used in the callback.
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- “value”: the value of the component property at the time the callback was fired.
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- “triggered”: (bool)Whether this input triggered the callback.
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Example usage:
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@app.callback(
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Output("container", "children"),
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inputs=dict(btn1=Input("btn-1", "n_clicks"), btn2=Input("btn-2", "n_clicks")),
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)
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def display(btn1, btn2):
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c = ctx.args_grouping
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if c.btn1.triggered:
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return f"Button 1 clicked {btn1} times"
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elif c.btn2.triggered:
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return f"Button 2 clicked {btn2} times"
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else:
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return "No clicks yet"
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"""
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return getattr(_get_context_value(), "args_grouping", [])
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@property
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@has_context
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def outputs_grouping(self):
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return getattr(_get_context_value(), "outputs_grouping", [])
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@property
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@has_context
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def outputs_list(self):
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if self.using_outputs_grouping:
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warnings.warn(
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"outputs_list is deprecated, use outputs_grouping instead",
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DeprecationWarning,
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)
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return getattr(_get_context_value(), "outputs_list", [])
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@property
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@has_context
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def inputs_list(self):
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if self.using_args_grouping:
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warnings.warn(
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"inputs_list is deprecated, use args_grouping instead",
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DeprecationWarning,
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)
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return getattr(_get_context_value(), "inputs_list", [])
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@property
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@has_context
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def states_list(self):
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if self.using_args_grouping:
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warnings.warn(
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"states_list is deprecated, use args_grouping instead",
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DeprecationWarning,
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)
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return getattr(_get_context_value(), "states_list", [])
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@property
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@has_context
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def response(self):
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return getattr(_get_context_value(), "dash_response")
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@staticmethod
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@has_context
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def record_timing(name, duration, description=None):
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"""Records timing information for a server resource.
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:param name: The name of the resource.
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:type name: string
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:param duration: The time in seconds to report. Internally, this
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is rounded to the nearest millisecond.
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:type duration: float
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:param description: A description of the resource.
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:type description: string or None
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"""
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timing_information = getattr(flask.g, "timing_information", {})
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if name in timing_information:
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raise KeyError(f'Duplicate resource name "{name}" found.')
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timing_information[name] = {"dur": round(duration * 1000), "desc": description}
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setattr(flask.g, "timing_information", timing_information)
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@property
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@has_context
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def using_args_grouping(self):
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"""
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Return True if this callback is using dictionary or nested groupings for
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Input/State dependencies, or if Input and State dependencies are interleaved
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"""
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return getattr(_get_context_value(), "using_args_grouping", [])
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@property
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@has_context
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def using_outputs_grouping(self):
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"""
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Return True if this callback is using dictionary or nested groupings for
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Output dependencies.
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"""
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return getattr(_get_context_value(), "using_outputs_grouping", [])
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@property
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@has_context
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def timing_information(self):
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return getattr(flask.g, "timing_information", {})
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@has_context
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def set_props(self, component_id: typing.Union[str, dict], props: dict):
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ctx_value = _get_context_value()
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_id = stringify_id(component_id)
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existing = ctx_value.updated_props.get(_id)
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if existing is not None:
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ctx_value.updated_props[_id] = {**existing, **props}
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else:
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ctx_value.updated_props[_id] = props
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@property
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@has_context
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def cookies(self):
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"""
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Get the cookies for the current callback.
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Works with background callbacks.
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"""
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return _get_from_context("cookies", {})
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@property
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@has_context
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def headers(self):
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"""
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Get the original headers for the current callback.
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Works with background callbacks.
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"""
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return _get_from_context("headers", {})
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@property
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@has_context
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def path(self):
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"""
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Path of the callback request with the query parameters.
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"""
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return _get_from_context("path", "")
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@property
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@has_context
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def remote(self):
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"""
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Remote addr of the callback request.
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"""
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return _get_from_context("remote", "")
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@property
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@has_context
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def origin(self):
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"""
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Origin of the callback request.
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"""
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return _get_from_context("origin", "")
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@property
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@has_context
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def custom_data(self):
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"""
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Custom data set by hooks.custom_data.
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"""
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return _get_from_context("custom_data", {})
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callback_context = CallbackContext()
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def set_props(component_id: typing.Union[str, dict], props: dict):
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"""
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Set the props for a component not included in the callback outputs.
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"""
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callback_context.set_props(component_id, props)
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