How to generate Dart from GraphQL - graphql to dart generator

Question

How can simple object types [1] such as interfaces &/ classes be generated from GraphQL schema definitions into Dart?

• Motivation
  • One single source of truth: GraphQL schema
  • From GraphQL all plain simple types are generated into multiple languages
    • in our case Typescript and Dart
• what we've tried so far
  • All solutions related [2] - even forks - does not do simple types
• Possible DIY approaches we know of
  • GraphQL Code Generator [3]
  • quicktype similar alternatives [4]

GraphQL into Typescript example

Given this schema definition

type Person {
    age: Int
    name: String!
}

Running this script

import { GraphQLDefinitionsFactory } from '@nestjs/graphql';
import { join } from 'path';


const definitionsFactory = new GraphQLDefinitionsFactory();

definitionsFactory.generate({
    typePaths: ['./**/*.graphql'],
    path: join(process.cwd(), './class.ts'),
    outputAs: 'class'
});

definitionsFactory.generate({
    typePaths: ['./src/**/*.graphql'],
    path: join(process.cwd(), './interface.ts'),
    outputAs: 'interface'
});

Output

export interface Person {
    age?: number;
    name: string;
}

export class Person {
    age?: number;
    name: string;
}

1: Simple Object Types should be just simple plain object types without annotations, encoding and decoding logic etc. 2: https://github.com/gql-dart/gql
3: https://graphql-code-generator.com
4: https://app.quicktype.io

Answer 1

I personally tried to use Artemis or hoped Apollo was branching out, but @Ryosuke's graphql_to_dart is straight forward and lean.

If you already have a GraphQL endpoint with your schema up and running, you just need to set up its graphql_config.yaml for example like this:

package_name: example
graphql_endpoint: http://example.com/graphql
models_directory_path: lib/graphql/models/

Given schema definition

type Person {
    age: Int
    name: String!
}

.dart Output

class Person{
  int age;
  String name;
  Person({
    this.age,this.name
  });

  Person.fromJson(Map<String, dynamic> json){
    age = json['age'];
    name = json['name'];
  }

  Map toJson(){
    Map _data = {};
    _data['age'] = age;
    _data['name'] = name;
    return _data;
  }
}

With the additional option type_override you can set custom scalar types as you prefer them.

Edit:

There is now an expanded version as PR. With the possibility to generate them outside of lib/ without import path conflicts, through an opt-out option dynamic_import_path: false.

The type_override keys also don't need to be explicitly written in lower case anymore.