Class: GraphQL::Schema

Inherits:
Object
  • Object
show all
Includes:
Define::InstanceDefinable
Defined in:
lib/graphql/schema.rb,
lib/graphql/schema/loader.rb,
lib/graphql/schema/printer.rb,
lib/graphql/schema/type_map.rb,
lib/graphql/schema/validation.rb,
lib/graphql/schema/reduce_types.rb,
lib/graphql/schema/possible_types.rb,
lib/graphql/schema/type_expression.rb,
lib/graphql/schema/middleware_chain.rb,
lib/graphql/schema/rescue_middleware.rb,
lib/graphql/schema/invalid_type_error.rb,
lib/graphql/schema/timeout_middleware.rb,
lib/graphql/schema/unique_within_type.rb,
lib/graphql/schema/catchall_middleware.rb

Overview

A GraphQL schema which may be queried with Query.

The Schema contains:

- types for exposing your application
- query analyzers for assessing incoming queries (including max depth & max complexity restrictions)
- execution strategies for running incoming queries
- middleware for interacting with execution

Schemas start with root types, Schema#query, Schema#mutation and Schema#subscription. The schema will traverse the tree of fields & types, using those as starting points. Any undiscoverable types may be provided with the `types` configuration.

Schemas can restrict large incoming queries with `max_depth` and `max_complexity` configurations. (These configurations can be overridden by specific calls to #execute)

Schemas can specify how queries should be executed against them. `query_execution_strategy`, `mutation_execution_strategy` and `subscription_execution_strategy` each apply to corresponding root types.

A schema accepts a `Relay::GlobalNodeIdentification` instance for use with Relay IDs.

Examples:

defining a schema

MySchema = GraphQL::Schema.define do
  query QueryType
  middleware PermissionMiddleware
  rescue_from(ActiveRecord::RecordNotFound) { "Not found" }
  # If types are only connected by way of interfaces, they must be added here
  orphan_types ImageType, AudioType
end

Defined Under Namespace

Modules: CatchallMiddleware, Loader, Printer, ReduceTypes, TypeExpression, UniqueWithinType Classes: InvalidTypeError, MiddlewareChain, PossibleTypes, RescueMiddleware, TimeoutMiddleware, TypeMap, Validation

Constant Summary collapse

DIRECTIVES =
[GraphQL::Directive::IncludeDirective, GraphQL::Directive::SkipDirective, GraphQL::Directive::DeprecatedDirective]
DYNAMIC_FIELDS =
["__type", "__typename", "__schema"]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Define::InstanceDefinable

#definition_proc=, included, #metadata

Constructor Details

#initialize(query: nil, mutation: nil, subscription: nil, max_depth: nil, max_complexity: nil, types: []) ⇒ Schema

Returns a new instance of Schema.

Parameters:

  • query (GraphQL::ObjectType) (defaults to: nil)

    the query root for the schema

  • mutation (GraphQL::ObjectType) (defaults to: nil)

    the mutation root for the schema

  • subscription (GraphQL::ObjectType) (defaults to: nil)

    the subscription root for the schema

  • max_depth (Integer) (defaults to: nil)

    maximum query nesting (if it's greater, raise an error)

  • types (Array<GraphQL::BaseType>) (defaults to: [])

    additional types to include in this schema


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# File 'lib/graphql/schema.rb', line 77

def initialize(query: nil, mutation: nil, subscription: nil, max_depth: nil, max_complexity: nil, types: [])
  if query
    warn("Schema.new is deprecated, use Schema.define instead")
  end
  @query    = query
  @mutation = mutation
  @subscription = subscription
  @max_depth = max_depth
  @max_complexity = max_complexity
  @orphan_types = types
  @directives = DIRECTIVES.reduce({}) { |m, d| m[d.name] = d; m }
  @static_validator = GraphQL::StaticValidation::Validator.new(schema: self)
  @middleware = []
  @query_analyzers = []
  @resolve_type_proc = nil
  @object_from_id_proc = nil
  @id_from_object_proc = nil
  # Default to the built-in execution strategy:
  @query_execution_strategy = GraphQL::Query::SerialExecution
  @mutation_execution_strategy = GraphQL::Query::SerialExecution
  @subscription_execution_strategy = GraphQL::Query::SerialExecution
end

Instance Attribute Details

#directivesObject (readonly)

Returns the value of attribute directives


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# File 'lib/graphql/schema.rb', line 67

def directives
  @directives
end

#id_from_object_procObject (readonly)

Returns the value of attribute id_from_object_proc


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# File 'lib/graphql/schema.rb', line 67

def id_from_object_proc
  @id_from_object_proc
end

#middlewareArray<#call> (readonly)

Returns Middlewares suitable for MiddlewareChain, applied to fields during execution.

Returns:

  • (Array<#call>)

    Middlewares suitable for MiddlewareChain, applied to fields during execution


# File 'lib/graphql/schema.rb', line 69

#object_from_id_procObject (readonly)

Returns the value of attribute object_from_id_proc


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# File 'lib/graphql/schema.rb', line 67

def object_from_id_proc
  @object_from_id_proc
end

#resolve_type_procObject (readonly)

Returns the value of attribute resolve_type_proc


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# File 'lib/graphql/schema.rb', line 67

def resolve_type_proc
  @resolve_type_proc
end

#static_validatorObject (readonly)

Returns the value of attribute static_validator


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# File 'lib/graphql/schema.rb', line 67

def static_validator
  @static_validator
end

Instance Method Details

#define(**kwargs, &block) ⇒ Object


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# File 'lib/graphql/schema.rb', line 110

def define(**kwargs, &block)
  super
  types
  # Assert that all necessary configs are present:
  validation_error = Validation.validate(self)
  validation_error && raise(NotImplementedError, validation_error)
  nil
end

#execute(*args) ⇒ Hash

Execute a query on itself. See Query#initialize for arguments.

Returns:

  • (Hash)

    query result, ready to be serialized as JSON


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# File 'lib/graphql/schema.rb', line 131

def execute(*args)
  query_obj = GraphQL::Query.new(self, *args)
  query_obj.result
end

#execution_strategy_for_operation(operation) ⇒ Object


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# File 'lib/graphql/schema.rb', line 181

def execution_strategy_for_operation(operation)
  case operation
  when "query"
    query_execution_strategy
  when "mutation"
    mutation_execution_strategy
  when "subscription"
    subscription_execution_strategy
  else
    raise ArgumentError, "unknown operation type: #{operation}"
  end
end

#get_field(parent_type, field_name) ⇒ Object

Resolve field named `field_name` for type `parent_type`. Handles dynamic fields `__typename`, `__type` and `__schema`, too


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# File 'lib/graphql/schema.rb', line 138

def get_field(parent_type, field_name)
  ensure_defined
  defined_field = parent_type.get_field(field_name)
  if defined_field
    defined_field
  elsif field_name == "__typename"
    GraphQL::Introspection::TypenameField.create(parent_type)
  elsif field_name == "__schema" && parent_type == query
    GraphQL::Introspection::SchemaField.create(self)
  elsif field_name == "__type" && parent_type == query
    GraphQL::Introspection::TypeByNameField.create(self.types)
  else
    nil
  end
end

#id_from_object(object, type, ctx) ⇒ String

Get a unique identifier from this object

Parameters:

Returns:

  • (String)

    a unique identifier for `object` which clients can use to refetch it


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# File 'lib/graphql/schema.rb', line 246

def id_from_object(object, type, ctx)
  ensure_defined
  if @id_from_object_proc.nil?
    raise(NotImplementedError, "Can't generate an ID for #{object.inspect} of type #{type}, schema's `id_from_object` must be defined")
  else
    @id_from_object_proc.call(object, type, ctx)
  end
end

#id_from_object=(new_proc) ⇒ Object

Parameters:

  • new_proc (#call)

    A new callable for generating unique IDs


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# File 'lib/graphql/schema.rb', line 256

def id_from_object=(new_proc)
  ensure_defined
  @id_from_object_proc = new_proc
end

#object_from_id(id, ctx) ⇒ Any

Fetch an application object by its unique id

Parameters:

  • id (String)

    A unique identifier, provided previously by this GraphQL schema

  • ctx (GraphQL::Query::Context)

    The context for the current query

Returns:

  • (Any)

    The application object identified by `id`


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# File 'lib/graphql/schema.rb', line 226

def object_from_id(id, ctx)
  ensure_defined
  if @object_from_id_proc.nil?
    raise(NotImplementedError, "Can't fetch an object for id \"#{id}\" because the schema's `object_from_id (id, ctx) -> { ... }` function is not defined")
  else
    @object_from_id_proc.call(id, ctx)
  end
end

#object_from_id=(new_proc) ⇒ Object

Parameters:

  • new_proc (#call)

    A new callable for fetching objects by ID


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# File 'lib/graphql/schema.rb', line 236

def object_from_id=(new_proc)
  ensure_defined
  @object_from_id_proc = new_proc
end

#possible_types(type_defn) ⇒ Array<GraphQL::ObjectType>

TODO: when `resolve_type` is schema level, can this be removed?

Parameters:

Returns:


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# File 'lib/graphql/schema.rb', line 162

def possible_types(type_defn)
  ensure_defined
  @interface_possible_types ||= GraphQL::Schema::PossibleTypes.new(self)
  @interface_possible_types.possible_types(type_defn)
end

#remove_handler(*args, &block) ⇒ Object


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# File 'lib/graphql/schema.rb', line 105

def remove_handler(*args, &block)
  ensure_defined
  rescue_middleware.remove_handler(*args, &block)
end

#rescue_from(*args, &block) ⇒ Object


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# File 'lib/graphql/schema.rb', line 100

def rescue_from(*args, &block)
  ensure_defined
  rescue_middleware.rescue_from(*args, &block)
end

#resolve_type(object, ctx) ⇒ GraphQL::ObjectType

Determine the GraphQL type for a given object. This is required for unions and interfaces (include Relay's node interface)

Parameters:

  • object (Any)

    An application object which GraphQL is currently resolving on

  • ctx (GraphQL::Query::Context)

    The context for the current query

Returns:


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# File 'lib/graphql/schema.rb', line 199

def resolve_type(object, ctx)
  ensure_defined

  if @resolve_type_proc.nil?
    raise(NotImplementedError, "Can't determine GraphQL type for: #{object.inspect}, define `resolve_type (obj, ctx) -> { ... }` inside `Schema.define`.")
  end

  type_result = @resolve_type_proc.call(object, ctx)
  if type_result.nil?
    nil
  elsif !type_result.is_a?(GraphQL::BaseType)
    type_str = "#{type_result} (#{type_result.class.name})"
    raise "resolve_type(#{object}) returned #{type_str}, but it should return a GraphQL type"
  else
    type_result
  end
end

#resolve_type=(new_resolve_type_proc) ⇒ Object


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# File 'lib/graphql/schema.rb', line 217

def resolve_type=(new_resolve_type_proc)
  ensure_defined
  @resolve_type_proc = new_resolve_type_proc
end

#root_type_for_operation(operation) ⇒ Object


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# File 'lib/graphql/schema.rb', line 168

def root_type_for_operation(operation)
  case operation
  when "query"
    query
  when "mutation"
    mutation
  when "subscription"
    subscription
  else
    raise ArgumentError, "unknown operation type: #{operation}"
  end
end

#type_from_ast(ast_node) ⇒ Object


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# File 'lib/graphql/schema.rb', line 154

def type_from_ast(ast_node)
  ensure_defined
  GraphQL::Schema::TypeExpression.build_type(self, ast_node)
end

#typesGraphQL::Schema::TypeMap

Returns `{ name => type }` pairs of types in this schema.

Returns:


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# File 'lib/graphql/schema.rb', line 120

def types
  @types ||= begin
    ensure_defined
    all_types = orphan_types + [query, mutation, subscription, GraphQL::Introspection::SchemaType]
    GraphQL::Schema::ReduceTypes.reduce(all_types.compact)
  end
end