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Emitting schema SDL

The TypeGraphQL main feature is creating schema using only TypeScript's classes and decorators. However, sometimes we might need the schema to be printed into a schema.gql file and there are a plenty of reasons for that. Mainly, schema SDL file is needed for GraphQL ecosystem tools that perform client-side queries autocompletion and validation. Some developers also may want to use it as a kinda snapshot for detecting schema regression or they just prefer to read the SDL file to explore the API instead of reading the complicated TypeGraphQL-based app code, navigating through GraphiQL or GraphQL Playground.

To accomplish this demand, TypeGraphQL allows you to create a schema definition file in two ways. The first one is automatically on every build of the schema - just pass emitSchemaFile: true to the buildSchema options in order to emit the schema.gql in the root of the project's working directory. You can also manually specify a path and the file name where the schema definition should be written.

const schema = await buildSchema({
  resolvers: [ExampleResolver],
  // automatically create `schema.gql` file with schema definition
  // in project's working directory
  emitSchemaFile: true,
  // or create the file with schema in selected path
  emitSchemaFile: path.resolve(__dirname, "snapshots/schema", "schema.gql"),
});

Second way to emit schema definition file is by doing it manually in a programmatic way. All you need to do is to use emitSchemaDefinitionFile function or it's sync version (emitSchemaDefinitionFileSync) and pass the selected path to it, along with the schema object. You can use this i.a. as part of a testing script that checks if the snapshot of the schema definition is correct or to automatically generate it on every file change during local development.

import { emitSchemaDefinitionFile, buildSchema } from "type-graphql";
// ...
hypotheticalFileWatcher.watch("./src/**/*.{resolver,type,input,arg}.ts", async () => {
  const schema = getSchemaNotFromBuildSchemaFunction();
  await emitSchemaDefinitionFile("/path/to/folder/schema.gql", schema);
});