Class: GraphQL::Stitching::Composer

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/stitching/composer.rb

Defined Under Namespace

Classes: BaseValidator, ComposerError, ValidateBoundaries, ValidateInterfaces, ValidationError

Constant Summary collapse

DEFAULT_VALUE_MERGER = 
->(values_by_location, _info) { values_by_location.values.find { !_1.nil? } }
DEFAULT_ROOT_FIELD_LOCATION_SELECTOR = 
->(locations, _info) { locations.last }
VALIDATORS = 
[
  "ValidateInterfaces",
  "ValidateBoundaries",
].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query_name: "Query", mutation_name: "Mutation", description_merger: nil, deprecation_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 19

def initialize(
  query_name: "Query",
  mutation_name: "Mutation",
  description_merger: nil,
  deprecation_merger: nil,
  directive_kwarg_merger: nil,
  root_field_location_selector: nil
)
  @query_name = query_name
  @mutation_name = mutation_name
  @description_merger = description_merger || DEFAULT_VALUE_MERGER
  @deprecation_merger = deprecation_merger || DEFAULT_VALUE_MERGER
  @directive_kwarg_merger = directive_kwarg_merger || DEFAULT_VALUE_MERGER
  @root_field_location_selector = root_field_location_selector || DEFAULT_ROOT_FIELD_LOCATION_SELECTOR
end

Instance Attribute Details

#candidate_types_by_name_and_location ⇒ Object (readonly)

Returns the value of attribute candidate_types_by_name_and_location.



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# File 'lib/graphql/stitching/composer.rb', line 9

def candidate_types_by_name_and_location
  @candidate_types_by_name_and_location
end

#mutation_name ⇒ Object (readonly)

Returns the value of attribute mutation_name.



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# File 'lib/graphql/stitching/composer.rb', line 9

def mutation_name
  @mutation_name
end

#query_name ⇒ Object (readonly)

Returns the value of attribute query_name.



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# File 'lib/graphql/stitching/composer.rb', line 9

def query_name
  @query_name
end

#schema_directives ⇒ Object (readonly)

Returns the value of attribute schema_directives.



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# File 'lib/graphql/stitching/composer.rb', line 9

def schema_directives
  @schema_directives
end

Instance Method Details

#build_directive(directive_name, directives_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 173

def build_directive(directive_name, directives_by_location)
  builder = self

  Class.new(GraphQL::Schema::Directive) do
    graphql_name(directive_name)
    description(builder.merge_descriptions(directive_name, directives_by_location))
    repeatable(directives_by_location.values.any?(&:repeatable?))
    locations(*directives_by_location.values.flat_map(&:locations).uniq)
    builder.build_merged_arguments(directive_name, directives_by_location, self)
  end
end

#build_enum_type(type_name, types_by_location, enum_usage) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 198

def build_enum_type(type_name, types_by_location, enum_usage)
  builder = self

  # "value" => "location" => enum_value
  enum_values_by_value_location = types_by_location.each_with_object({}) do |(location, type_candidate), memo|
    type_candidate.enum_values.each do |enum_value_candidate|
      memo[enum_value_candidate.value] ||= {}
      memo[enum_value_candidate.value][location] ||= {}
      memo[enum_value_candidate.value][location] = enum_value_candidate
    end
  end

  # intersect input enum types
  if enum_usage.fetch(type_name, []).include?(:write)
    enum_values_by_value_location.reject! do |value, enum_values_by_location|
      types_by_location.keys.length != enum_values_by_location.keys.length
    end
  end

  Class.new(GraphQL::Schema::Enum) do
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))
    builder.build_merged_directives(type_name, types_by_location, self)

    enum_values_by_value_location.each do |value, enum_values_by_location|
      enum_value = value(value,
        value: value,
        description: builder.merge_descriptions(type_name, enum_values_by_location, enum_value: value),
        deprecation_reason: builder.merge_deprecations(type_name, enum_values_by_location, enum_value: value),
      )

      builder.build_merged_directives(type_name, enum_values_by_location, enum_value, enum_value: value)
    end
  end
end

#build_enum_usage_map(schemas) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 536

def build_enum_usage_map(schemas)
  reads = []
  writes = []

  schemas.each do |schema|
    schema.types.values.each do |type|
      next if Supergraph::INTROSPECTION_TYPES.include?(type.graphql_name)

      if type.kind.object? || type.kind.interface?
        type.fields.values.each do |field|
          field_type = field.type.unwrap
          reads << field_type.graphql_name if field_type.kind.enum?

          field.arguments.values.each do |argument|
            argument_type = argument.type.unwrap
            writes << argument_type.graphql_name if argument_type.kind.enum?
          end
        end

      elsif type.kind.input_object?
        type.arguments.values.each do |argument|
          argument_type = argument.type.unwrap
          writes << argument_type.graphql_name if argument_type.kind.enum?
        end
      end
    end
  end

  usage = reads.uniq.each_with_object({}) do |enum_name, memo|
    memo[enum_name] ||= []
    memo[enum_name] << :read
  end
  writes.uniq.each_with_object(usage) do |enum_name, memo|
    memo[enum_name] ||= []
    memo[enum_name] << :write
  end
end

#build_input_object_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 282

def build_input_object_type(type_name, types_by_location)
  builder = self

  Class.new(GraphQL::Schema::InputObject) do
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))
    builder.build_merged_arguments(type_name, types_by_location, self)
    builder.build_merged_directives(type_name, types_by_location, self)
  end
end

#build_interface_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 251

def build_interface_type(type_name, types_by_location)
  builder = self

  Module.new do
    include GraphQL::Schema::Interface
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))

    interface_names = types_by_location.values.flat_map { _1.interfaces.map(&:graphql_name) }
    interface_names.uniq.each do |interface_name|
      implements(builder.build_type_binding(interface_name))
    end

    builder.build_merged_fields(type_name, types_by_location, self)
    builder.build_merged_directives(type_name, types_by_location, self)
  end
end

#build_merged_arguments(type_name, members_by_location, owner, field_name: nil) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 329

def build_merged_arguments(type_name, members_by_location, owner, field_name: nil)
  # "argument_name" => "location" => argument
  args_by_name_location = members_by_location.each_with_object({}) do |(location, member_candidate), memo|
    member_candidate.arguments.each do |argument_name, argument|
      memo[argument_name] ||= {}
      memo[argument_name][location] ||= {}
      memo[argument_name][location] = argument
    end
  end

  args_by_name_location.each do |argument_name, arguments_by_location|
    value_types = arguments_by_location.values.map(&:type)

    if arguments_by_location.length != members_by_location.length
      if value_types.any?(&:non_null?)
        path = [type_name, field_name, argument_name].compact.join(".")
        raise ComposerError, "Required argument `#{path}` must be defined in all locations." # ...or hidden?
      end
      next
    end

    # Getting double args sometimes... why?
    return if owner.arguments.any? { _1.first == argument_name }

    type = merge_value_types(type_name, value_types, argument_name: argument_name, field_name: field_name)
    schema_argument = owner.argument(
      argument_name,
      description: merge_descriptions(type_name, arguments_by_location, argument_name: argument_name, field_name: field_name),
      deprecation_reason: merge_deprecations(type_name, arguments_by_location, argument_name: argument_name, field_name: field_name),
      type: Util.unwrap_non_null(type),
      required: type.non_null?,
      camelize: false,
    )

    build_merged_directives(type_name, arguments_by_location, schema_argument, field_name: field_name, argument_name: argument_name)
  end
end

#build_merged_directives(type_name, members_by_location, owner, field_name: nil, argument_name: nil, enum_value: nil) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 367

def build_merged_directives(type_name, members_by_location, owner, field_name: nil, argument_name: nil, enum_value: nil)
  directives_by_name_location = members_by_location.each_with_object({}) do |(location, member_candidate), memo|
    member_candidate.directives.each do |directive|
      memo[directive.graphql_name] ||= {}
      memo[directive.graphql_name][location] ||= {}
      memo[directive.graphql_name][location] = directive
    end
  end

  directives_by_name_location.each do |directive_name, directives_by_location|
    directive_class = @schema_directives[directive_name]
    next unless directive_class

    # handled by deprecation_reason merger...
    next if directive_class.graphql_name == "deprecated"

    kwarg_values_by_name_location = directives_by_location.each_with_object({}) do |(location, directive), memo|
      directive.arguments.keyword_arguments.each do |key, value|
        key = key.to_s
        next unless directive_class.arguments[key]

        memo[key] ||= {}
        memo[key][location] = value
      end
    end

    kwargs = kwarg_values_by_name_location.each_with_object({}) do |(kwarg_name, kwarg_values_by_location), memo|
      memo[kwarg_name.to_sym] = @directive_kwarg_merger.call(kwarg_values_by_location, {
        type_name: type_name,
        field_name: field_name,
        argument_name: argument_name,
        enum_value: enum_value,
        directive_name: directive_name,
        kwarg_name: kwarg_name,
      }.compact!)
    end

    owner.directive(directive_class, **kwargs)
  end
end

#build_merged_fields(type_name, types_by_location, owner) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 297

def build_merged_fields(type_name, types_by_location, owner)
  # "field_name" => "location" => field
  fields_by_name_location = types_by_location.each_with_object({}) do |(location, type_candidate), memo|
    @field_map[type_name] ||= {}
    type_candidate.fields.each do |field_name, field_candidate|
      @field_map[type_name][field_candidate.name] ||= []
      @field_map[type_name][field_candidate.name] << location

      memo[field_name] ||= {}
      memo[field_name][location] ||= {}
      memo[field_name][location] = field_candidate
    end
  end

  fields_by_name_location.each do |field_name, fields_by_location|
    value_types = fields_by_location.values.map(&:type)

    type = merge_value_types(type_name, value_types, field_name: field_name)
    schema_field = owner.field(
      field_name,
      description: merge_descriptions(type_name, fields_by_location, field_name: field_name),
      deprecation_reason: merge_deprecations(type_name, fields_by_location, field_name: field_name),
      type: Util.unwrap_non_null(type),
      null: !type.non_null?,
      camelize: false,
    )

    build_merged_arguments(type_name, fields_by_location, schema_field, field_name: field_name)
    build_merged_directives(type_name, fields_by_location, schema_field, field_name: field_name)
  end
end

#build_object_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 234

def build_object_type(type_name, types_by_location)
  builder = self

  Class.new(GraphQL::Schema::Object) do
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))

    interface_names = types_by_location.values.flat_map { _1.interfaces.map(&:graphql_name) }
    interface_names.uniq.each do |interface_name|
      implements(builder.build_type_binding(interface_name))
    end

    builder.build_merged_fields(type_name, types_by_location, self)
    builder.build_merged_directives(type_name, types_by_location, self)
  end
end

#build_scalar_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 185

def build_scalar_type(type_name, types_by_location)
  built_in_type = GraphQL::Schema::BUILT_IN_TYPES[type_name]
  return built_in_type if built_in_type

  builder = self

  Class.new(GraphQL::Schema::Scalar) do
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))
    builder.build_merged_directives(type_name, types_by_location, self)
  end
end

#build_type_binding(type_name) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 293

def build_type_binding(type_name)
  GraphQL::Schema::LateBoundType.new(@mapped_type_names.fetch(type_name, type_name))
end

#build_union_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 269

def build_union_type(type_name, types_by_location)
  builder = self

  Class.new(GraphQL::Schema::Union) do
    graphql_name(type_name)
    description(builder.merge_descriptions(type_name, types_by_location))

    possible_names = types_by_location.values.flat_map { _1.possible_types.map(&:graphql_name) }.uniq
    possible_types(*possible_names.map { builder.build_type_binding(_1) })
    builder.build_merged_directives(type_name, types_by_location, self)
  end
end

#expand_abstract_boundaries(schema) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 523

def expand_abstract_boundaries(schema)
  @boundary_map.keys.each do |type_name|
    boundary_type = schema.types[type_name]
    next unless boundary_type.kind.abstract?

    expanded_types = Util.expand_abstract_type(schema, boundary_type)
    expanded_types.select { @candidate_types_by_name_and_location[_1.graphql_name].length > 1 }.each do |expanded_type|
      @boundary_map[expanded_type.graphql_name] ||= []
      @boundary_map[expanded_type.graphql_name].push(*@boundary_map[type_name])
    end
  end
end

#extract_boundaries(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 459

def extract_boundaries(type_name, types_by_location)
  types_by_location.each do |location, type_candidate|
    type_candidate.fields.each do |field_name, field_candidate|
      boundary_type_name = field_candidate.type.unwrap.graphql_name
      boundary_structure = Util.flatten_type_structure(field_candidate.type)

      field_candidate.directives.each do |directive|
        next unless directive.graphql_name == GraphQL::Stitching.stitch_directive

        key = directive.arguments.keyword_arguments.fetch(:key)
        key_selections = GraphQL.parse("{ #{key} }").definitions[0].selections

        if key_selections.length != 1
          raise ComposerError, "Boundary key at #{type_name}.#{field_name} must specify exactly one key."
        end

        argument_name = key_selections[0].alias
        argument_name ||= if field_candidate.arguments.size == 1
          field_candidate.arguments.keys.first
        end

        argument = field_candidate.arguments[argument_name]
        unless argument
          # contextualize this... "boundaries with multiple args need mapping aliases."
          raise ComposerError, "Invalid boundary argument `#{argument_name}` for #{type_name}.#{field_name}."
        end

        argument_structure = Util.flatten_type_structure(argument.type)
        if argument_structure.length != boundary_structure.length
          raise ComposerError, "Mismatched input/output for #{type_name}.#{field_name}.#{argument_name} boundary. Arguments must map directly to results."
        end

        @boundary_map[boundary_type_name] ||= []
        @boundary_map[boundary_type_name] << {
          "location" => location,
          "selection" => key_selections[0].name,
          "field" => field_candidate.name,
          "arg" => argument_name,
          "list" => boundary_structure.first[:list],
          "type_name" => boundary_type_name,
        }
      end
    end
  end
end

#merge_deprecations(type_name, members_by_location, field_name: nil, argument_name: nil, enum_value: nil) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 449

def merge_deprecations(type_name, members_by_location, field_name: nil, argument_name: nil, enum_value: nil)
  strings_by_location = members_by_location.each_with_object({}) { |(l, m), memo| memo[l] = m.deprecation_reason }
  @deprecation_merger.call(strings_by_location, {
    type_name: type_name,
    field_name: field_name,
    argument_name: argument_name,
    enum_value: enum_value,
  }.compact!)
end

#merge_descriptions(type_name, members_by_location, field_name: nil, argument_name: nil, enum_value: nil) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 439

def merge_descriptions(type_name, members_by_location, field_name: nil, argument_name: nil, enum_value: nil)
  strings_by_location = members_by_location.each_with_object({}) { |(l, m), memo| memo[l] = m.description }
  @description_merger.call(strings_by_location, {
    type_name: type_name,
    field_name: field_name,
    argument_name: argument_name,
    enum_value: enum_value,
  }.compact!)
end

#merge_value_types(type_name, type_candidates, field_name: nil, argument_name: nil) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 408

def merge_value_types(type_name, type_candidates, field_name: nil, argument_name: nil)
  path = [type_name, field_name, argument_name].compact.join(".")
  alt_structures = type_candidates.map { Util.flatten_type_structure(_1) }
  basis_structure = alt_structures.shift

  alt_structures.each do |alt_structure|
    if alt_structure.length != basis_structure.length
      raise ComposerError, "Cannot compose mixed list structures at `#{path}`."
    end

    if alt_structure.last[:name] != basis_structure.last[:name]
      raise ComposerError, "Cannot compose mixed types at `#{path}`."
    end
  end

  type = GraphQL::Schema::BUILT_IN_TYPES.fetch(
    basis_structure.last[:name],
    build_type_binding(basis_structure.last[:name])
  )

  basis_structure.reverse!.each_with_index do |basis, index|
    rev_index = basis_structure.length - index - 1
    non_null = alt_structures.each_with_object([!basis[:null]]) { |s, m| m << !s[rev_index][:null] }

    type = type.to_list_type if basis[:list]
    type = type.to_non_null_type if argument_name ? non_null.any? : non_null.all?
  end

  type
end

#perform(locations_input) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 35

def perform(locations_input)
  reset!
  schemas, executables = prepare_locations_input(locations_input)

  # "directive_name" => "location" => candidate_directive
  @candidate_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

  # "Typename" => merged_directive
  @schema_directives = @candidate_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" => candidate_type
  @candidate_types_by_name_and_location = schemas.each_with_object({}) do |(location, schema), memo|
    raise ComposerError, "Location keys must be strings" unless location.is_a?(String)
    raise ComposerError, "The subscription operation is not supported." if schema.subscription

    schema.types.each do |type_name, type_candidate|
      next if Supergraph::INTROSPECTION_TYPES.include?(type_name)

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

      type_name = @query_name if type_candidate == schema.query
      type_name = @mutation_name if type_candidate == schema.mutation
      @mapped_type_names[type_candidate.graphql_name] = type_name if type_candidate.graphql_name != type_name

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

  enum_usage = build_enum_usage_map(schemas.values)

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

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

    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"
      extract_boundaries(type_name, types_by_location)
      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 ComposerError, "Unexpected kind encountered for `#{type_name}`. Found: #{kinds.first}."
    end
  end

  builder = self
  schema = Class.new(GraphQL::Schema) do
    orphan_types schema_types.values
    query schema_types[builder.query_name]
    mutation schema_types[builder.mutation_name]
    directives builder.schema_directives.values

    own_orphan_types.clear
  end

  select_root_field_locations(schema)
  expand_abstract_boundaries(schema)

  supergraph = Supergraph.new(
    schema: schema,
    fields: @field_map,
    boundaries: @boundary_map,
    executables: executables,
  )

  VALIDATORS.each do |validator|
    klass = Object.const_get("GraphQL::Stitching::Composer::#{validator}")
    klass.new.perform(supergraph, self)
  end

  supergraph
end

#prepare_locations_input(locations_input) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 134

def prepare_locations_input(locations_input)
  schemas = {}
  executables = {}

  locations_input.each do |location, input|
    schema = input[:schema]

    if schema.nil?
      raise ComposerError, "A schema is required for `#{location}` location."
    elsif !(schema.is_a?(Class) && schema <= GraphQL::Schema)
      raise ComposerError, "The schema for `#{location}` location must be a GraphQL::Schema class."
    end

    if input[:stitch]
      stitch_directive = Class.new(GraphQL::Schema::Directive) do
        graphql_name(GraphQL::Stitching.stitch_directive)
        locations :FIELD_DEFINITION
        argument :key, String
        repeatable true
      end

      input[:stitch].each do |dir|
        type = dir[:type_name] ? schema.types[dir[:type_name]] : schema.query
        raise ComposerError, "Invalid stitch directive type `#{dir[:type_name]}`" unless type

        field = type.fields[dir[:field_name]]
        raise ComposerError, "Invalid stitch directive field `#{dir[:field_name]}`" unless field

        field.directive(stitch_directive, **dir.slice(:key))
      end
    end

    schemas[location.to_s] = schema
    executables[location.to_s] = input[:executable] || schema
  end

  return schemas, executables
end

#select_root_field_locations(schema) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 505

def select_root_field_locations(schema)
  [schema.query, schema.mutation].tap(&:compact!).each do |root_type|
    root_type.fields.each do |root_field_name, root_field|
      root_field_locations = @field_map[root_type.graphql_name][root_field_name]
      next unless root_field_locations.length > 1

      target_location = @root_field_location_selector.call(root_field_locations, {
        type_name: root_type.graphql_name,
        field_name: root_field_name,
      })
      next unless root_field_locations.include?(target_location)

      root_field_locations.reject! { _1 == target_location }
      root_field_locations.unshift(target_location)
    end
  end
end