Validate component properties #264 - March 1

.circleci/config.yml

@@ -40,9 +40,7 @@ jobs:
           command: |
               . venv/bin/activate
               pylint dash setup.py --rcfile=$PYLINTRC
-              pylint tests -d all -e C0410,C0411,C0412,C0413,W0109
               flake8 dash setup.py
-              flake8 --ignore=E123,E126,E501,E722,E731,F401,F841,W503,W504 --exclude=metadata_test.py tests
 
       - run:
           name: Run tests
@@ -51,6 +49,7 @@ jobs:
               python --version
               python -m unittest tests.development.test_base_component
               python -m unittest tests.development.test_component_loader
+              python -m unittest tests.development.test_component_validation
               python -m unittest tests.test_integration
               python -m unittest tests.test_resources
               python -m unittest tests.test_configs

.circleci/requirements/dev-requirements-py37.txt

@@ -9,8 +9,11 @@ mock
 tox
 tox-pyenv
 six
+numpy
+pandas
 plotly>=2.0.8
 requests[security]
 flake8
 pylint==2.1.1
 astroid==2.0.4
+Cerberus

.circleci/requirements/dev-requirements.txt

@@ -10,7 +10,10 @@ tox
 tox-pyenv
 mock
 six
+numpy
+pandas
 plotly>=2.0.8
 requests[security]
 flake8
 pylint==1.9.2
+Cerberus

dash/dash.py

@@ -8,8 +8,10 @@
 import pkgutil
 import warnings
 import re
+import pprint
 
 from functools import wraps
+from textwrap import dedent
 
 import plotly
 import dash_renderer
@@ -20,6 +22,8 @@
 from .dependencies import Event, Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component
+from .development.validator import (DashValidator,
+                                    generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -84,6 +88,7 @@ def __init__(
             external_scripts=None,
             external_stylesheets=None,
             suppress_callback_exceptions=None,
+            suppress_validation_exceptions=None,
             components_cache_max_age=None,
             **kwargs):
 
@@ -126,6 +131,10 @@ def __init__(
                 'suppress_callback_exceptions',
                 suppress_callback_exceptions, env_configs, False
             ),
+            'suppress_validation_exceptions': _configs.get_config(
+                'suppress_validation_exceptions',
+                suppress_validation_exceptions, env_configs, False
+            ),
             'routes_pathname_prefix': routes_pathname_prefix,
             'requests_pathname_prefix': requests_pathname_prefix,
             'include_assets_files': _configs.get_config(
@@ -572,7 +581,7 @@ def react(self, *args, **kwargs):
             'Use `callback` instead. `callback` has a new syntax too, '
             'so make sure to call `help(app.callback)` to learn more.')
 
-    def _validate_callback(self, output, inputs, state, events):
+    def _validate_callback_definition(self, output, inputs, state, events):
         # pylint: disable=too-many-branches
         layout = self._cached_layout or self._layout_value()
 
@@ -710,7 +719,7 @@ def _validate_callback(self, output, inputs, state, events):
                 output.component_id,
                 output.component_property).replace('    ', ''))
 
-    def _validate_callback_output(self, output_value, output):
+    def _debug_callback_serialization_error(self, output_value, output):
         valid = [str, dict, int, float, type(None), Component]
 
         def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -828,7 +837,7 @@ def _validate_value(val, index=None):
     # relationships
     # pylint: disable=dangerous-default-value
     def callback(self, output, inputs=[], state=[], events=[]):
-        self._validate_callback(output, inputs, state, events)
+        self._validate_callback_definition(output, inputs, state, events)
 
         callback_id = '{}.{}'.format(
             output.component_id, output.component_property
@@ -850,13 +859,11 @@ def callback(self, output, inputs=[], state=[], events=[]):
 
         def wrap_func(func):
             @wraps(func)
-            def add_context(*args, **kwargs):
-
-                output_value = func(*args, **kwargs)
+            def add_context(validated_output):
                 response = {
                     'response': {
                         'props': {
-                            output.component_property: output_value
+                            output.component_property: validated_output
                         }
                     }
                 }
@@ -867,7 +874,10 @@ def add_context(*args, **kwargs):
                         cls=plotly.utils.PlotlyJSONEncoder
                     )
                 except TypeError:
-                    self._validate_callback_output(output_value, output)
+                    self._debug_callback_serialization_error(
+                        validated_output,
+                        output
+                    )
                     raise exceptions.InvalidCallbackReturnValue('''
                     The callback for property `{property:s}`
                     of component `{id:s}` returned a value
@@ -884,6 +894,7 @@ def add_context(*args, **kwargs):
                     mimetype='application/json'
                 )
 
+            self.callback_map[callback_id]['func'] = func
             self.callback_map[callback_id]['callback'] = add_context
 
             return add_context
@@ -912,7 +923,85 @@ def dispatch(self):
                 c['id'] == component_registration['id']
             ][0])
 
-        return self.callback_map[target_id]['callback'](*args)
+        output_value = self.callback_map[target_id]['func'](*args)
+
+        # Only validate if we get required information from renderer
+        # and validation is not turned off by user
+        if (
+                not self.config.suppress_validation_exceptions and
+                'namespace' in output and
+                'type' in output
+        ):
+            # Python2.7 might make these keys and values unicode
+            namespace = str(output['namespace'])
+            component_type = str(output['type'])
+            component_id = str(output['id'])
+            component_property = str(output['property'])
+            callback_func_name = self.callback_map[target_id]['func'].__name__
+            self._validate_callback_output(namespace, component_type,
+                                           component_id, component_property,
+                                           callback_func_name,
+                                           args, output_value)
+
+        return self.callback_map[target_id]['callback'](output_value)
+
+    def _validate_callback_output(self, namespace, component_type,
+                                  component_id, component_property,
+                                  callback_func_name, args, value):
+        module = sys.modules[namespace]
+        component = getattr(module, component_type)
+        # pylint: disable=protected-access
+        validator = DashValidator({
+            component_property: component._schema.get(component_property, {})
+        })
+        valid = validator.validate({component_property: value})
+        if not valid:
+            error_message = dedent("""\
+
+                A Dash Callback produced an invalid value!
+
+                Dash tried to update the `{component_property}` prop of the
+                `{component_name}` with id `{component_id}` by calling the
+                `{callback_func_name}` function with `{args}` as arguments.
+
+                This function call returned `{value}`, which did not pass
+                validation tests for the `{component_name}` component.
+
+                The expected schema for the `{component_property}` prop of the
+                `{component_name}` component is:
+
+                ***************************************************************
+                {component_schema}
+                ***************************************************************
+
+                The errors in validation are as follows:
+
+            """).format(
+                component_property=component_property,
+                component_name=component.__name__,
+                component_id=component_id,
+                callback_func_name=callback_func_name,
+                args='({})'.format(", ".join(map(repr, args))),
+                value=value,
+                component_schema=pprint.pformat(
+                    component._schema[component_property]
+                )
+            )
+
+            raise exceptions.CallbackOutputValidationError(
+                generate_validation_error_message(
+                    validator.errors,
+                    0,
+                    error_message
+                )
+            )
+        # Must also validate initialization of newly created components
+        if component_property == 'children':
+            if isinstance(value, Component):
+                value.validate()
+                for component in value.traverse():
+                    if isinstance(component, Component):
+                        component.validate()
 
     def _validate_layout(self):
         if self.layout is None:
@@ -929,6 +1018,11 @@ def _validate_layout(self):
 
         component_ids = {layout_id} if layout_id else set()
         for component in to_validate.traverse():
+            if (
+                    not self.config.suppress_validation_exceptions and
+                    isinstance(component, Component)
+            ):
+                component.validate()
             component_id = getattr(component, 'id', None)
             if component_id and component_id in component_ids:
                 raise exceptions.DuplicateIdError(
@@ -1054,5 +1148,9 @@ def run_server(self,
         :return:
         """
         debug = self.enable_dev_tools(debug, dev_tools_serve_dev_bundles)
+        if not debug:
+            # Do not throw debugging exceptions in production.
+            self.config.suppress_validation_exceptions = True
+            self.config.suppress_callback_exceptions = True
         self.server.run(port=port, debug=debug,
                         **flask_run_options)