TypeScript template feature: generate full schema type

This adds a new `schemaType` option to the TypeScript template. When used, this option will add a type to the generated TypeScript code that represents the entirety of the input GraphQL schema's type system. Each type from the schema will be placed as a property on the interface and given its declared type.

The new interface is named `Schema`, optionally prefixed by the `interfacePrefix` option and placed within the optional `schemaNamespace` namespace.

This type is not generated by default. It is useful when the context of the schema as a whole is needed, such as when determining whether a GraphQL type name used in code is properly referencing a type that exists in a target GraphQL schema.

Author: steverice

packages/templates/typescript/README.md

@@ -101,6 +101,10 @@ This will cause the codegen to output `readonly` properties and `ReadonlyArray`.
 
 This will cause the codegen to output types for resolvers.
 
+### `schemaType` (or `CODEGEN_SCHEMA_TYPE`, default value: `false`)
+
+This will cause the codegen to output a single type that represents the entire schema.
+
 ### `noNamespaces` (or `CODEGEN_NO_NAMESPACES`, default value: `null`)
 
 This will cause the codegen not to use `namespace` in typings

packages/templates/typescript/src/config.ts

@@ -4,6 +4,7 @@ import * as schema from './schema.handlebars';
 import * as resolver from './resolver.handlebars';
 import * as documents from './documents.handlebars';
 import * as selectionSet from './selection-set.handlebars';
+import * as typeProperty from './type-property.handlebars';
 import * as fragments from './fragments.handlebars';
 import * as enumTemplate from './enum.handlebars';
 import { EInputType, GeneratorConfig } from 'graphql-codegen-core';
@@ -25,6 +26,7 @@ export const config: GeneratorConfig = {
     resolver,
     documents,
     selectionSet,
+    typeProperty,
     fragments,
     enum: enumTemplate
   },

packages/templates/typescript/src/schema.handlebars

@@ -63,9 +63,20 @@ export interface {{ toPascalCase name }}{{ toPascalCase ../name }}Args {
 export type {{ toPascalCase name }} = {{#each possibleTypes}}{{ toPascalCase this}}{{#unless @last}} | {{/unless}}{{/each}};
 
 {{/each}}
+{{#if config.schemaType }}
+{{#if types}}
+export interface {{@root.config.interfacePrefix}}Schema {
+  {{#each scalars}}{{~> typeProperty prefix=false }}{{/each}}
+  {{#each types}}{{~> typeProperty prefix=true }}{{/each}}
+  {{#each enums}}{{~> typeProperty prefix=true }}{{/each}}
+  {{#each unions}}{{~> typeProperty prefix=true }}{{/each}}
+  {{#each interfaces}}{{~> typeProperty prefix=true }}{{/each}}
+}
+{{/if}}
+{{/if}}
 {{#if @root.config.schemaNamespace ~}} } {{~/if}}
 {{#ifCond @root.config.resolvers "!==" false }}
 {{#each types}}
 {{~> resolver }}
 {{/each}}
-{{/ifCond}}
+{{/ifCond}}

packages/templates/typescript/src/type-property.handlebars

@@ -0,0 +1 @@
+{{#if @root.config.immutableTypes }}readonly {{/if}}{{ name }}: {{#if prefix }}{{@root.config.interfacePrefix}}{{/if}}{{ toPascalCase name }} {{ toComment description }};