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_STRING_MERGER = 
->(str_by_location, _info) { str_by_location.values.find { !_1.nil? } }
VALIDATORS = 
[
  "ValidateInterfaces",
  "ValidateBoundaries",
].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schemas:, query_name: "Query", mutation_name: "Mutation", description_merger: nil, deprecation_merger: nil) ⇒ Composer

Returns a new instance of Composer.



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# File 'lib/graphql/stitching/composer.rb', line 18

def initialize(
  schemas:,
  query_name: "Query",
  mutation_name: "Mutation",
  description_merger: nil,
  deprecation_merger: nil
)
  @schemas = schemas
  @query_name = query_name
  @mutation_name = mutation_name
  @field_map = {}
  @boundary_map = {}
  @mapped_type_names = {}

  @description_merger = description_merger || DEFAULT_STRING_MERGER
  @deprecation_merger = deprecation_merger || DEFAULT_STRING_MERGER
end

Instance Attribute Details

#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

#subschema_types_by_name_and_location ⇒ Object (readonly)

Returns the value of attribute subschema_types_by_name_and_location.



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

def subschema_types_by_name_and_location
  @subschema_types_by_name_and_location
end

Instance Method Details

#build_enum_type(type_name, types_by_location, enum_usage) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 127

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))

    enum_values_by_value_location.each do |value, enum_values_by_location|
      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),
      )
    end
  end
end

#build_enum_usage_map(schemas) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 399

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 = Util.get_named_type(field.type)
          reads << field_type.graphql_name if field_type.kind.enum?

          field.arguments.values.each do |argument|
            argument_type = Util.get_named_type(argument.type)
            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 = Util.get_named_type(argument.type)
          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 205

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)
  end
end

#build_interface_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 176

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)
  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 249

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 }

    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: merge_value_types(type_name, value_types, argument_name: argument_name, field_name: field_name),
      required: value_types.any?(&:non_null?),
      camelize: false,
    )
  end
end

#build_merged_fields(type_name, types_by_location, owner) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 219

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)

    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: merge_value_types(type_name, value_types, field_name: field_name),
      null: !value_types.all?(&:non_null?),
      camelize: false,
    )

    build_merged_arguments(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 160

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)
  end
end

#build_scalar_type(type_name, types_by_location) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 115

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))
  end
end

#build_type_binding(type_name) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 215

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 193

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) })
  end
end

#expand_abstract_boundaries(schema) ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 386

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

    possible_types = Util.get_possible_types(schema, boundary_type)
    possible_types.select { @subschema_types_by_name_and_location[_1.graphql_name].length > 1 }.each do |possible_type|
      @boundary_map[possible_type.graphql_name] ||= []
      @boundary_map[possible_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 340

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 = Util.get_named_type(field_candidate.type).graphql_name
      boundary_list = Util.get_list_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_list = Util.get_list_structure(argument.type)
        if argument_list.length != boundary_list.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_list.any?,
          "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 330

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 320

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 284

def merge_value_types(type_name, type_candidates, field_name: nil, argument_name: nil)
  path = [type_name, field_name, argument_name].compact.join(".")
  named_types = type_candidates.map { Util.get_named_type(_1).graphql_name }.uniq

  unless named_types.all? { _1 == named_types.first }
    raise ComposerError, "Cannot compose mixed types at `#{path}`. Found: #{named_types.join(", ")}."
  end

  type = GraphQL::Schema::BUILT_IN_TYPES.fetch(named_types.first, build_type_binding(named_types.first))
  list_structures = type_candidates.map { Util.get_list_structure(_1) }

  if list_structures.any?(&:any?)
    if list_structures.any? { _1.length != list_structures.first.length }
      raise ComposerError, "Cannot compose mixed list structures at `#{path}`."
    end

    list_structures.each(&:reverse!)
    list_structures.first.each_with_index do |current, index|
      # input arguments use strongest nullability, readonly fields use weakest
      non_null = list_structures.public_send(argument_name ? :any? : :all?) do |list_structure|
        list_structure[index].start_with?("non_null")
      end

      case current
      when "list", "non_null_list"
        type = type.to_list_type
        type = type.to_non_null_type if non_null
      when "element", "non_null_element"
        type = type.to_non_null_type if non_null
      end
    end
  end

  type
end

#perform ⇒ Object 



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# File 'lib/graphql/stitching/composer.rb', line 36

def perform
  # "Typename" => "location" => candidate_type
  @subschema_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 = @subschema_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

    unless kinds.all? { _1 == kinds.first }
      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: #{kind}."
    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]

    own_orphan_types.clear
  end

  expand_abstract_boundaries(schema)

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

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

  supergraph
end