kristianmandrup / graph-schema-json-writer

Extension to graphSchemaToJson to write schema object back to typedef string or TypeScript source file

GraphQL schema JSON Writer

Extension to graphSchemaToJson to write the schema generated from a GraphQL type def to various outputs:

• Typescript source files
• GraphQL type def files

Also includes accessor functionality to better work with the schema object generated.

Usage

{
  Person: {
    fields: {
      name: {
        type: 'String',
        directives: {},
        isNullable: false,
        isList: false
      },
      age: {
        type: 'Int',
        directives: {
          range: {
            min: 0,
            max: 130
          }
        },
        isNullable: false,
        isList: false
      },
      gender: {
        type: 'Gender',
        directives: {},
        isNullable: false,
        isList: false
      }
    },
    directives: {},
    type: 'Object',
    implements: []
  },
  Gender: {
    fields: ['male', 'female'],
    directives: {},
    type: 'Enum'
  }
}

Accessor

import { schemaToJS } from "../src/schema";
import { accessor } from "graph-schema-json-writer";
const { schemaByType, filteredSchema } = accessor;
/// ... generate JSON schema
const jsSchema = schemaToJS(schema);

// schema where all entries with keys starting with __ are filtered out
const filteredMap = filteredSchema(jsSchema);

// soreted by type
const typeMap = schemaByType(jsSchema);
console.log(typeMap);

{
    Object: {
        Person: {
            // ....
        }
    },
    Enum: {
        Gender: {
            // ...
        }
    }
}

Writer

import { schemaToJS } from "../src/schema";
import { writer } from "graph-schema-json-writer";
const { writeToTypeDef } = writer;
/// ... generate JSON schema
const jsSchema = schemaToJS(schema);

// schema where all entries with keys starting with __ are filtered out
const typeDef = writeToTypeDef(jsSchema);
console.log(typeDef);

Should output the (original) GraphqL type def, nicely formatted:

type Person {
  name: String!
  age: Int! @range(min: 0, max: 130)
  gender: Gender!
}

enum Gender {
  male
  female
}

Writing typescript source files

The writer also supports writing a TypeScript class, complete with:

• extends class
• implements interfaces
• decorators for class itself and fields and properties
  • imports for the decorators, interfaces and class extended

import { schemaToJS } from "../src/schema";
import { writer, createClass } from "graph-schema-json-writer";
/// ... generate JSON schema
const jsSchema = schemaToJS(schema);
const classType = createClass(jsSchema);

const importsMap = {
  Range: "class-validator",
  BaseEntity: "typeorm",
  Entity: "typeorm"
};
const body = classType.writeClass("Person", jsSchema.Person, {
  importsMap
});
console.log(sourceFileTxt);

Output a TypeScript class with decorators

import { BaseEntity, Entity } from 'typeorm';
import { Range } from 'class-validator';

@Entity()
class Person extends BaseEntity {
  name: string

  @Range(min: 0, max: 130)
  age: number
}

Writing source files

Use the SourceFile class to write source files to disk:

import { createSoureFileWriter, importsMap } from "graph-schema-json-writer";

// include typical import maps, such as for typeorm and class-validator
const myImportsMap = {
  ...importsMap.all
  // ...custom additions or overrides
};
const writeOpts = {
  importsMap: myImportsMap,
  srcFileDir: fs.join(__dirname, "db/model"),
  only: ["Person", "Gender"],
  enumRefs: true, // resolve enumRefs using importsMap
  // classRefs true, // resolve classRefs using importsMap
  validate: true // validate that each const reference has an entry in importsMap
};

const srcFileWriter = createSoureFileWriter(writeOpts);
await srcFileWriter.writeTypeDefs(jsSchema, writeOpts);
await srcFileWriter.writeIndexFiles();

Files written, assuming __dirname is /src, using default flat strategy:

  /src
    /db
      /models
        Person.ts
        Gender.ts
        index.ts

Using defaults:

import { writeTypeDefs, importsMap } from "graph-schema-json-writer";
// ...
await writeTypeDefs(jsSchema, {
  importsMap: importsMap.all,
  srcFileDir: fs.join(__dirname, "db/model"),
  strategy: "type-folder",
  only: ["Person", "Gender"],
  index: true // also add index files
});

Files written using type-folder strategy:

  /src
    /db
      /models
        /class
          Person.ts
          index.ts
        /enum/
          Gender.ts
          index.ts
        index.ts

Note: The SourceFileWriter has not yet been fully tested and could use some futher refactoring. It should include enough building blocks for you to compose a solution to fit your needs ;)

Imports map

Imports maps now have support for aliases

importsMap = {
  range: { name: "Range", importPath: "validator" }
};

Will result in an aliased import:

import { Range as range } from 'validator';

Use cases

This class writer could be used for writing classed for TypeORM, NestJS or TypeGraphQL etc.

Note that the class writer supports passing decorators in place of directives.

License

MIT