Class: GraphWeaver::Codegen

Inherits:
Object
  • Object
show all
Defined in:
lib/graph_weaver/codegen.rb

Overview

Generates plain, statically-typecheckable Ruby from a GraphQL query + schema: nested T::Structs, from_h casting code, and a sig'd execute method. Unlike StructTypes (which builds classes at parse time, visible only at runtime), the output is source on disk — srb tc sees the exact result type of each query.

Supports queries and mutations; plain fields, inline fragments, named fragment spreads (including interface type conditions), union- and interface-typed fields (dispatch on __typename), enums (generated T::Enum), and typed variables (kwargs on execute). Input objects and subscriptions are still open.

Defined Under Namespace

Classes: EnumNode, List, NonNull, ObjectNode, Scalar, UnionNode, VarDef

Constant Summary collapse

SCALARS =

sorbet types for scalars

{
  "ID" => "String",
  "String" => "String",
  "Int" => "Integer",
  "Float" => "Float",
  "Boolean" => "T::Boolean",
  "Date" => "Date",
}.freeze
SCALAR_CASTS =

deserialization for scalars whose wire format differs from their Ruby type; anything absent passes through untouched

{
  "Date" => ->(expr) { "Date.iso8601(#{expr})" },
}.freeze
SCALAR_SERIALIZERS =

the inverse, for serializing variables onto the wire

{
  "Date" => ->(expr) { "#{expr}.iso8601" },
}.freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema:, executor_const:, query:, module_name:) ⇒ Codegen

executor_const names anything responding to execute(query, variables:) whose result to_hs into => ..., "errors" => ... — a Schema class for in-process execution, or an HttpExecutor for a remote endpoint. The generated execute also accepts an executor: override at runtime.



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# File 'lib/graph_weaver/codegen.rb', line 212

def initialize(schema:, executor_const:, query:, module_name:)
  @schema = schema
  @executor_const = executor_const
  @query = query.strip
  @module_name = module_name
end

Class Method Details

.load(schema:, executor_const:, query:, module_name:) ⇒ Object

Development convenience: generate + eval in one step, no build artifact or checked-in file. Same runtime semantics as the generated file, but invisible to srb tc — use the build step for static typing.



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# File 'lib/graph_weaver/codegen.rb', line 222

def self.load(schema:, executor_const:, query:, module_name:)
  source = new(schema:, executor_const:, query:, module_name:).generate
  Object.class_eval(source, "(struct_codegen)", 1)
  Object.const_get(module_name)
end

Instance Method Details

#generate ⇒ Object 



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# File 'lib/graph_weaver/codegen.rb', line 230

def generate
  errors = @schema.validate(@query)
  if errors.any?
    raise ArgumentError, "invalid query: #{errors.map(&:message).join("; ")}"
  end

  doc = GraphQL.parse(@query)
  @fragments = doc.definitions
    .grep(GraphQL::Language::Nodes::FragmentDefinition)
    .to_h { |fragment| [fragment.name, fragment] }
  @variable_enums = {}

  operation = doc.definitions.grep(GraphQL::Language::Nodes::OperationDefinition).first
  root_type = case operation&.operation_type
  when "query", nil then @schema.query
  when "mutation" then @schema.mutation
  else raise NotImplementedError, "unsupported operation: #{operation.operation_type}"
  end

  variables = operation.variables.map do |var|
    node = ast_type_ref(var.type)
    # a variable is optional when nullable or defaulted; optional kwargs
    # default to nil and are omitted from the wire
    required = node.non_null? && var.default_value.nil?
    VarDef.new(underscore(var.name), var.name, node, required)
  end

  root = object_node(root_type, operation.selections, "Result")

  out = []
  out << "# typed: strict"
  out << "# frozen_string_literal: true"
  out << ""
  out << "# Generated by GraphWeaver — do not edit."
  out << ""
  out << "module #{@module_name}"
  out << "  extend T::Sig"
  out << ""
  out << "  QUERY = T.let(<<~'GRAPHQL', String)"
  @query.each_line { |line| out << "    #{line}".rstrip }
  out << "  GRAPHQL"
  out << ""
  @variable_enums.each_value do |enum|
    emit_enum(enum, out, 1)
    out << ""
  end
  emit_nested(root, out, 1)
  out << ""
  emit_execute(out, variables)
  out << "end"

  out.join("\n") + "\n"
end