Validate component properties #264 - March 1

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

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
             value = self.get(name)
             if value:
                 return value
+
+
+def _merge(x, y):
+    z = x.copy()
+    z.update(y)
+    return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+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
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+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:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
             external_scripts=None,
             external_stylesheets=None,
             suppress_callback_exceptions=None,
+            suppress_validation_exceptions=None,
             components_cache_max_age=None,
             **kwargs):
 
@@ -128,6 +153,10 @@ 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(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
                 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,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
         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
                         }
                     }
                 }
@@ -918,7 +945,10 @@ 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
@@ -935,6 +965,7 @@ 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
@@ -978,7 +1009,62 @@ 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 = _callback_validation_error_template.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:
@@ -995,6 +1081,11 @@ 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(
@@ -1292,6 +1383,10 @@ def run_server(self,
             dev_tools_silence_routes_logging,
         )
 
+        if not debug:
+            # Do not throw validation exceptions in production.
+            self.config.suppress_validation_exceptions = True
+
         if self._dev_tools.silence_routes_logging:
             # Since it's silenced, the address don't show anymore.
             host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+    _explicitize_args,
+    generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
     """
     Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
     # it to be `null` or whether that was just the default value.
     # The solution might be to deal with default values better although
     # not all component authors will supply those.
-    c = '''class {typename}(Component):
+    c = '''\
+schema = {schema}
+
+class {typename}(Component):
     """{docstring}"""
+    _schema = schema
     @_explicitize_args
     def __init__(self, {default_argtext}):
         self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
         self.available_properties = {list_of_valid_keys}
         self.available_wildcard_properties =\
             {list_of_valid_wildcard_attr_prefixes}
-
         _explicit_args = kwargs.pop('_explicit_args')
         _locals = locals()
         _locals.update(kwargs)  # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
         default_argtext = "children=None, "
         argtext = 'children=children, **args'
     else:
-        default_argtext = ""
+        default_argtext = ''
         argtext = '**args'
     default_argtext += ", ".join(
         [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
          p != 'setProps'] + ["**kwargs"]
     )
     required_args = required_props(props)
+    schema = {
+        k: generate_property_schema(v)
+        for k, v in props.items() if not k.endswith("-*")
+    }
     return c.format(
         typename=typename,
         namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
         docstring=docstring,
         default_argtext=default_argtext,
         argtext=argtext,
-        required_props=required_args
+        required_props=required_args,
+        schema=schema
     )