Class: GraphQL::Stitching::Composer

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/stitching/composer.rb,
lib/graphql/stitching/composer/base_validator.rb,
lib/graphql/stitching/composer/validate_interfaces.rb,
lib/graphql/stitching/composer/type_resolver_config.rb,
lib/graphql/stitching/composer/validate_type_resolvers.rb

Overview

Composer receives many individual GraphQL::Schema instances representing various graph locations and merges them into one combined Supergraph that is validated for integrity.

Defined Under Namespace

Classes: BaseValidator, TypeResolverConfig, ValidateInterfaces, ValidateTypeResolvers

Constant Summary collapse

NO_DEFAULT_VALUE =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

begin
  class T < GraphQL::Schema::Object
    field(:f, String) do
      argument(:a, String)
    end
  end

  T.get_field("f").get_argument("a").default_value
end
BASIC_VALUE_MERGER =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

->(values_by_location, _info) { values_by_location.values.find { !_1.nil? } }
BASIC_ROOT_FIELD_LOCATION_SELECTOR =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

->(locations, _info) { locations.last }
COMPOSITION_VALIDATORS =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future. 

[
  ValidateInterfaces,
  ValidateTypeResolvers,
].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query_name: "Query", mutation_name: "Mutation", subscription_name: "Subscription", description_merger: nil, deprecation_merger: nil, default_value_merger: nil, directive_kwarg_merger: nil, root_field_location_selector: nil) ⇒ Composer

Returns a new instance of Composer.



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# File 'lib/graphql/stitching/composer.rb', line 52

def initialize(
  query_name: "Query",
  mutation_name: "Mutation",
  subscription_name: "Subscription",
  description_merger: nil,
  deprecation_merger: nil,
  default_value_merger: nil,
  directive_kwarg_merger: nil,
  root_field_location_selector: nil
)
  @query_name = query_name
  @mutation_name = mutation_name
  @subscription_name = subscription_name
  @description_merger = description_merger || BASIC_VALUE_MERGER
  @deprecation_merger = deprecation_merger || BASIC_VALUE_MERGER
  @default_value_merger = default_value_merger || BASIC_VALUE_MERGER
  @directive_kwarg_merger = directive_kwarg_merger || BASIC_VALUE_MERGER
  @root_field_location_selector = root_field_location_selector || BASIC_ROOT_FIELD_LOCATION_SELECTOR
  
  @field_map = {}
  @resolver_map = {}
  @resolver_configs = {}
  @mapped_type_names = {}
  @subgraph_directives_by_name_and_location = nil
  @subgraph_types_by_name_and_location = nil
  @schema_directives = nil
end

Instance Attribute Details

#mutation_name ⇒ String (readonly)

Returns name of the Mutation type in the composed schema.

Returns:

  • (String) —

    name of the Mutation type in the composed schema.



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# File 'lib/graphql/stitching/composer.rb', line 41

def mutation_name
  @mutation_name
end

#query_name ⇒ String (readonly)

Returns name of the Query type in the composed schema.

Returns:

  • (String) —

    name of the Query type in the composed schema.



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# File 'lib/graphql/stitching/composer.rb', line 38

def query_name
  @query_name
end

#schema_directives ⇒ Object (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/graphql/stitching/composer.rb', line 50

def schema_directives
  @schema_directives
end

#subgraph_types_by_name_and_location ⇒ Object (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/graphql/stitching/composer.rb', line 47

def subgraph_types_by_name_and_location
  @subgraph_types_by_name_and_location
end

#subscription_name ⇒ String (readonly)

Returns name of the Subscription type in the composed schema.

Returns:

  • (String) —

    name of the Subscription type in the composed schema.



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# File 'lib/graphql/stitching/composer.rb', line 44

def subscription_name
  @subscription_name
end

Instance Method Details

#perform(locations_input) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 80

def perform(locations_input)
  if @subgraph_types_by_name_and_location
    raise CompositionError, "Composer may only perform once per instance."
  end

  schemas, executables = prepare_locations_input(locations_input)

  # "directive_name" => "location" => subgraph_directive
  @subgraph_directives_by_name_and_location = schemas.each_with_object({}) do |(location, schema), memo|
    (schema.directives.keys - schema.default_directives.keys - GraphQL::Stitching.stitching_directive_names).each do |directive_name|
      memo[directive_name] ||= {}
      memo[directive_name][location] = schema.directives[directive_name]
    end
  end

  # "directive_name" => merged_directive
  @schema_directives = @subgraph_directives_by_name_and_location.each_with_object({}) do |(directive_name, directives_by_location), memo|
    memo[directive_name] = build_directive(directive_name, directives_by_location)
  end

  @schema_directives.merge!(GraphQL::Schema.default_directives)

  # "Typename" => "location" => subgraph_type
  @subgraph_types_by_name_and_location = schemas.each_with_object({}) do |(location, schema), memo|
    raise CompositionError, "Location keys must be strings" unless location.is_a?(String)

    introspection_types = schema.introspection_system.types.keys
    schema.types.each do |type_name, subgraph_type|
      next if introspection_types.include?(type_name)

      if type_name == @query_name && subgraph_type != schema.query
        raise CompositionError, "Query name \"#{@query_name}\" is used by non-query type in #{location} schema."
      elsif type_name == @mutation_name && subgraph_type != schema.mutation
        raise CompositionError, "Mutation name \"#{@mutation_name}\" is used by non-mutation type in #{location} schema."
      elsif type_name == @subscription_name && subgraph_type != schema.subscription
        raise CompositionError, "Subscription name \"#{@subscription_name}\" is used by non-subscription type in #{location} schema."
      end

      type_name = @query_name if subgraph_type == schema.query
      type_name = @mutation_name if subgraph_type == schema.mutation
      type_name = @subscription_name if subgraph_type == schema.subscription
      @mapped_type_names[subgraph_type.graphql_name] = type_name if subgraph_type.graphql_name != type_name

      memo[type_name] ||= {}
      memo[type_name][location] = subgraph_type
    end
  end

  enum_usage = build_enum_usage_map(schemas.values)

  # "Typename" => merged_type
  schema_types = @subgraph_types_by_name_and_location.each_with_object({}) do |(type_name, types_by_location), memo|
    kinds = types_by_location.values.map { _1.kind.name }.tap(&:uniq!)

    if kinds.length > 1
      raise CompositionError, "Cannot merge different kinds for `#{type_name}`. Found: #{kinds.join(", ")}."
    end

    extract_resolvers(type_name, types_by_location) if type_name == @query_name

    memo[type_name] = case kinds.first
    when "SCALAR"
      build_scalar_type(type_name, types_by_location)
    when "ENUM"
      build_enum_type(type_name, types_by_location, enum_usage)
    when "OBJECT"
      build_object_type(type_name, types_by_location)
    when "INTERFACE"
      build_interface_type(type_name, types_by_location)
    when "UNION"
      build_union_type(type_name, types_by_location)
    when "INPUT_OBJECT"
      build_input_object_type(type_name, types_by_location)
    else
      raise CompositionError, "Unexpected kind encountered for `#{type_name}`. Found: #{kinds.first}."
    end
  end

  builder = self
  schema = Class.new(GraphQL::Schema) do
    add_type_and_traverse(schema_types.values, root: false)
    orphan_types(schema_types.values.select { |t| t.respond_to?(:kind) && t.kind.object? })
    query schema_types[builder.query_name]
    mutation schema_types[builder.mutation_name]
    subscription schema_types[builder.subscription_name]
    directives builder.schema_directives.values

    own_orphan_types.clear
  end

  select_root_field_locations(schema)
  expand_abstract_resolvers(schema, schemas)

  supergraph = Supergraph.new(
    schema: schema,
    fields: @field_map,
    resolvers: @resolver_map,
    executables: executables,
  )

  COMPOSITION_VALIDATORS.each do |validator_class|
    validator_class.new.perform(supergraph, self)
  end

  supergraph
end