Source code for py_gql.validation.visitors

# -*- coding: utf-8 -*-

from typing import List, Mapping, Optional, Sequence, Tuple, TypeVar, Union

from .._utils import DefaultOrderedDict, OrderedDict, deduplicate, find_one
from ..exc import UnknownEnumValue, UnknownType, ValidationError
from ..lang import ast as _ast
from ..lang.visitor import DispatchingVisitor
from ..schema import (
from ..schema.introspection import (

T = TypeVar("T")
N = TypeVar("N", bound=_ast.Node)
MMap = Mapping[str, Mapping[str, T]]
LMap = Mapping[str, List[T]]
OptList = List[Optional[T]]

VariableUsages = MMap[
        Optional[Union[EnumType, ScalarType, InputObjectType]],
        Optional[Union[_ast.Argument, _ast.Field]],

def _peek(
    lst: Sequence[T], count: int = 1, default: Optional[T] = None
) -> Optional[T]:
    return lst[-1 * count] if len(lst) >= count else default

def _get_field_def(schema, parent_type, field):
    name =
    if parent_type is schema.query_type:
        if name ==
        if name ==

    if (
        isinstance(parent_type, GraphQLCompositeType)
        and name ==

    if isinstance(parent_type, (ObjectType, InterfaceType)):
        return parent_type.field_map.get(name, None)

    return None

[docs]class ValidationVisitor(DispatchingVisitor): """ Visitor class used for validating GraphQL documents. Subclass this to implement custom validators. Use :meth:`add_error` to register errors and :class:`py_gql.lang.visitor.SkipNode` to prevent validating child nodes when parent node is invalid. Args: schema: Schema to validate against (for known types, directives, etc.). type_info: Type information collector provided by :func:`~py_gql.validation.validate`. Attributes: schema (py_gql.schema.Schema): Schema to validate against (for known types, directives, etc.). type_info (TypeInfoVisitor): Type information collector provided by :func:`~py_gql.validation.validate`. errors (List[ValidationError]): Collected errors. """ def __init__(self, schema: Schema, type_info: "TypeInfoVisitor"): super(ValidationVisitor, self).__init__() self.schema = schema self.type_info = type_info self.errors = [] # type: List[ValidationError]
[docs] def add_error( self, message: str, nodes: Optional[Sequence[_ast.Node]] = None ) -> None: """ Register an error Args: message (str): Error description nodes (Optional[List[py_gql.lang.ast.Node]]): Nodes where the error originated from. """ self.errors.append(ValidationError(message, nodes))
[docs] def enter(self, node: N) -> N: super().enter(node) return node
class VariablesCollector(ValidationVisitor): """ Custom validation visitor tracking tracks all variable definitions and usage. """ def __init__(self, schema, type_info): super(VariablesCollector, self).__init__(schema, type_info) self._op = None self._op_variables = DefaultOrderedDict( OrderedDict ) # type: VariableUsages self._op_defined_variables = DefaultOrderedDict( OrderedDict ) # type: MMap[_ast.VariableDefinition] self._op_fragments = DefaultOrderedDict(list) # type: LMap[str] self._fragment = None self._fragment_variables = DefaultOrderedDict( OrderedDict ) # type: VariableUsages self._fragment_fragments = DefaultOrderedDict(list) # type: LMap[str] self._in_var_def = False def enter_operation_definition(self, node): self._op = if else "" def leave_operation_definition(self, _node): self._op = None def enter_fragment_definition(self, node): self._fragment = def leave_fragment_definition(self, _node): self._fragment = None def enter_fragment_spread(self, node): name = if self._op is not None: self._op_fragments[self._op].append(name) elif self._fragment is not None and name != self._fragment: self._fragment_fragments[self._fragment].append(name) def enter_variable_definition(self, node): self._in_var_def = True if self._op is not None: name = self._op_defined_variables[self._op][name] = node # type: ignore def leave_variable_definition(self, _node): self._in_var_def = False def enter_variable(self, node): var = input_type = self.type_info.input_type input_value_def = self.type_info.input_value_def if self._in_var_def: pass elif self._op is not None: self._op_variables[self._op][var] = ( # type: ignore node, input_type, input_value_def, ) elif self._fragment is not None: self._fragment_variables[self._fragment][var] = ( # type: ignore node, input_type, input_value_def, ) def _flatten_fragments(self): for parent, children in self._fragment_fragments.items(): for child in deduplicate(children): for op in self._op_fragments.keys(): if parent in self._op_fragments[op]: self._op_fragments[op].append(child) def leave_document(self, _): self._flatten_fragments() # This is a very basic re-implementation of the reference javascript # implementation which is compatible with our version of AST visitors # and it can most likley be improved. class TypeInfoVisitor(DispatchingVisitor): """ AST visitor ecurisvely tracking the current types and field definitions. All tracked types are considered with regards to the provided schema, however unknown types and other unexpected errors will be downgraded to null values in order to not crash the traversal. This leaves the consumer responsible to handle such cases. Warning: When using this alongside other visitors (such as when using :class:`py_gql.lang.visitor.ChainedVisitor`), this visitor **must** to be the first one to visit the nodes in order for the information provided donwstream to be accurate. Args: schema (py_gql.schema.Schema): Reference schema to extract types from Attributes: type: Current type if applicable. parent_type: Current type if applicable. input_type: Current input type if applicable (when visiting arguments). parent_input_type: Current parent input type if applicable (when visiting input objects). field: Current field definition if applicable (when visiting object). input_value_def: Current input value definition (e.g. arg def, input field) if applicable. """ __slots__ = ( "_schema", "_type_stack", "_input_type_stack", "_parent_type_stack", "_field_stack", "_input_value_def_stack", "directive", "argument", "enum_value", ) def __init__(self, schema): self._schema = schema self._type_stack = [] # type: OptList[GraphQLCompositeType] self._parent_type_stack = [] # type: OptList[GraphQLCompositeType] self._input_type_stack = [] # type: OptList[GraphQLType] self._field_stack = [] # type: OptList[Field] self._input_value_def_stack = [] # type: OptList[InputValue] self.directive = None # type: Optional[Directive] self.argument = None # type: Optional[Argument] self.enum_value = None # type: Optional[EnumValue] @property def type(self) -> Optional[GraphQLCompositeType]: return _peek(self._type_stack) @property def parent_type(self) -> Optional[GraphQLCompositeType]: return _peek(self._parent_type_stack, 1) @property def input_type(self) -> Optional[GraphQLType]: return _peek(self._input_type_stack, 1) @property def parent_input_type(self) -> Optional[InputObjectType]: t = _peek(self._input_type_stack, 2) return t if isinstance(t, InputObjectType) else None @property def field(self) -> Optional[Field]: return _peek(self._field_stack) @property def input_value_def(self) -> Optional[InputValue]: return _peek(self._input_value_def_stack) def _get_field_def(self, node): parent_type = self.parent_type return ( _get_field_def(self._schema, parent_type, node) if parent_type else None ) def _type_from_ast(self, type_node): try: return self._schema.get_type_from_literal(type_node) except UnknownType: return None def _leave_input_value(self): self._input_type_stack.pop() self._input_value_def_stack.pop() def enter_selection_set(self, node): named_type = unwrap_type(self.type) if self.type else None self._parent_type_stack.append( named_type if isinstance(named_type, GraphQLCompositeType) else None ) return node def leave_selection_set(self, _node): self._parent_type_stack.pop() def enter_field(self, node): field_def = self._get_field_def(node) self._field_stack.append(field_def) self._type_stack.append( field_def.type if field_def and is_output_type(field_def.type) else None ) return node def leave_field(self, _node): self._type_stack.pop() self._field_stack.pop() def enter_directive(self, node): self.directive = self._schema.directives.get( return node def leave_directive(self, _node): self.directive = None def enter_operation_definition(self, node): type_ = { "query": self._schema.query_type, "mutation": self._schema.mutation_type, "subscription": self._schema.subscription_type, }.get(node.operation, None) self._type_stack.append( type_ if isinstance(type_, ObjectType) else None ) return node def leave_operation_definition(self, _node): self._type_stack.pop() def enter_fragment_definition(self, node): type_ = self._type_from_ast(node.type_condition) self._type_stack.append(type_ if is_output_type(type_) else None) return node def leave_fragment_definition(self, _node): self._type_stack.pop() def enter_inline_fragment(self, node): if node.type_condition: type_ = self._type_from_ast(node.type_condition) self._type_stack.append(type_ if is_output_type(type_) else None) else: self._type_stack.append( self.type if self.type and is_output_type(self.type) else None ) return node def leave_inline_fragment(self, _node): self._type_stack.pop() def enter_variable_definition(self, node): type_ = self._type_from_ast(node.type) self._input_type_stack.append(type_ if is_input_type(type_) else None) return node def leave_variable_definition(self, _node): self._input_type_stack.pop() def enter_argument(self, node): ctx = self.directive or self.field if ctx: name = self.argument = find_one(ctx.arguments, lambda a: == name) self._input_value_def_stack.append(self.argument) self._input_type_stack.append( self.argument.type if self.argument and is_input_type(self.argument.type) else None ) else: self.argument = None self._input_type_stack.append(None) self._input_value_def_stack.append(None) return node def leave_argument(self, _node): self.argument = None self._leave_input_value() def enter_list_value(self, node): item_type = unwrap_type(self.input_type) if self.input_type else None self._input_type_stack.append( item_type if item_type and is_input_type(item_type) else None ) # List positions never have a default value. self._input_value_def_stack.append(None) return node def leave_list_value(self, _node): self._leave_input_value() def enter_object_field(self, node): object_type = unwrap_type(self.input_type) if self.input_type else None if isinstance(object_type, InputObjectType): name = field_def = find_one(object_type.fields, lambda f: == name) self._input_value_def_stack.append(field_def) self._input_type_stack.append( field_def.type if field_def and is_input_type(field_def.type) else None ) else: self._input_type_stack.append(None) self._input_value_def_stack.append(None) return node def leave_object_field(self, _node): self._leave_input_value() def enter_enum_value(self, node): enum = unwrap_type(self.input_type) if self.input_type else None if isinstance(enum, EnumType): try: self.enum_value = enum.get_value(node.value) except UnknownEnumValue: self.enum_value = None return node def leave_enum_value(self, _node): self.enum_value = None