graphql_schema 1.0.0

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An implementation of GraphQL's type system in Dart. Supports any platform where Dart runs. The decisions made in the design of this library were done to make the experience as similar to the JavaScript reference implementation as possible, and to also correctly implement the official specification.

Contains functionality to build all GraphQL types:

  • String
  • Int
  • Float
  • Boolean
  • GraphQLObjectType
  • GraphQLUnionType
  • GraphQLEnumType
  • GraphQLInputObjectType
  • Date - ISO-8601 Date string, deserializes to a Dart DateTime object

Of course, for a full description of GraphQL's type system, see the official specification:

Mostly analogous to graphql-js; many names are verbatim:


It's easy to define a schema with the helper functions:

final GraphQLSchema todoSchema = new GraphQLSchema(
    query: objectType('Todo', [
  field('text', graphQLString.nonNullable()),
  field('created_at', graphQLDate)

All GraphQL types are generic, in order to leverage Dart's strong typing support.


GraphQL types can serialize and deserialize input data. The exact implementation of this depends on the type.

var iso8601String = graphQLDate.serialize(new;
var date = graphQLDate.deserialize(iso8601String);


GraphQL types can validate input data.

var validation = myType.validate('@root', {...});

if (validation.successful) {
} else {


  • graphQLSchema - Create a GraphQLSchema
  • objectType - Create a GraphQLObjectType with fields
  • field - Create a GraphQLField with a type/argument/resolver
  • listOf - Create a GraphQLListType with the provided innerType
  • inputObjectType - Creates a GraphQLInputObjectType
  • inputField - Creates a field for a GraphQLInputObjectType


All of the GraphQL scalar types are built in, as well as a Date type:

  • graphQLString
  • graphQLId
  • graphQLBoolean
  • graphQLInt
  • graphQLFloat
  • graphQLDate

Non-Nullable Types

You can easily make a type non-nullable by calling its nonNullable method.

List Types

Support for list types is also included. Use the listType helper for convenience.

/// A non-nullable list of non-nullable integers

Input values and parameters

Take the following GraphQL query:

   anime {
     characters(title: "Hunter x Hunter") {

The field characters accepts a parameter, title. To reproduce this in package:graphql_schema, use GraphQLFieldInput:

final GraphQLObjectType queryType = objectType('AnimeQuery', fields: [
    inputs: [
      new GraphQLFieldInput('title', graphQLString.nonNullable())

final GraphQLObjectType characterType = objectType('Character', fields: [
  field('name', graphQLString),
  field('age', graphQLInt),

In the majority of cases where you use GraphQL, you will be delegate the actual fetching of data to a database object, or some asynchronous resolver function.

package:graphql_schema includes this functionality in the resolve property, which is passed a context object and a Map<String, dynamic> of arguments.

A hypothetical example of the above might be:

var field = field(
  resolve: (_, args) async {
    return await myDatabase.findCharacters(args['title']);


import 'package:graphql_schema/graphql_schema.dart';

final GraphQLSchema todoSchema = new GraphQLSchema(
  queryType: objectType('Todo', fields: [
      resolve: resolveToNull,
      resolve: resolveToNull,

main() {
  // Validation
  var validation = todoSchema.queryType.validate(
      'foo': 'bar',
      'text': null,
      'created_at': 24,

  if (validation.successful) {
    print('This is valid data!!!');
  } else {
    print('Invalid data.');
    validation.errors.forEach((s) => print('  * $s'));

  // Serialization
    'text': 'Clean your room!',
    'created_at': new Duration(days: 10))

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  graphql_schema: ^1.0.0

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter packages get

Alternatively, your editor might support pub get or flutter packages get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:graphql_schema/graphql_schema.dart';
Version Uploaded Documentation Archive
1.0.0 Aug 5, 2018 Go to the documentation of graphql_schema 1.0.0 Download graphql_schema 1.0.0 archive
1.0.0-beta Jul 19, 2017 Go to the documentation of graphql_schema 1.0.0-beta Download graphql_schema 1.0.0-beta archive
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Learn more about scoring.

We analyzed this package on Aug 10, 2018, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.0.0
  • pana: 0.11.8


Detected platforms: Flutter, web, other

No platform restriction found in primary library package:graphql_schema/graphql_schema.dart.

Issues and suggestions


Changelog entries help clients to follow the progress in your code.

The description is too short.

Add more detail about the package, what it does and what is its target use case. Try to write at least 60 characters.

Fix lib/src/object_type.dart.

Analysis of lib/src/object_type.dart reported 3 hints:

line 153 col 17: Always override hashCode if overriding ==.

line 262 col 17: Always override hashCode if overriding ==.

line 293 col 17: Always override hashCode if overriding ==.

Fix lib/src/enum.dart.

Analysis of lib/src/enum.dart reported 2 hints:

line 65 col 17: Always override hashCode if overriding ==.

line 98 col 17: Always override hashCode if overriding ==.

Fix additional 6 files with analysis or formatting issues.

Additional issues in the following files:

  • lib/src/type.dart (2 hints)
  • lib/src/argument.dart (1 hint)
  • lib/src/field.dart (1 hint)
  • lib/src/gen.dart (Run dartfmt to format lib/src/gen.dart.)
  • lib/src/union.dart (1 hint)
  • lib/src/validation_result.dart (Run dartfmt to format lib/src/validation_result.dart.)


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.8.0 <3.0.0
collection ^1.0.0 1.14.11
meta ^1.0.0 1.1.6
source_span ^1.0.0 1.4.1
Transitive dependencies
charcode 1.1.2
path 1.6.2
Dev dependencies
test ^0.12.0