graphql_schema 1.0.4

graphql_schema #

Pub build status

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:

Usage #

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.

Serialization #

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);

Validation #

GraphQL types can validate input data.

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

if (validation.successful) {
} else {

Helpers #

  • 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

Types #

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']);

1.0.4 #

  • Add convert method to types, to avoid some annoying generics bugs.

1.0.3 #

  • enumTypeFromStrings now returns GraphQLEnumType<String>.

1.0.2 #

  • Added GraphQLClass().
  • Added typeName.

1.0.1 #

  • Dart 2 updates.


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: ^1.0.4

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter pub get

Alternatively, your editor might support pub get or flutter pub 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';
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Learn more about scoring.

We analyzed this package on Feb 13, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.7.1
  • pana: 0.13.5

Health suggestions

Fix lib/src/object_type.dart. (-11.78 points)

Analysis of lib/src/object_type.dart reported 25 hints, including:

line 27 col 7: Unnecessary new keyword.

line 31 col 7: Unnecessary new keyword.

line 33 col 67: Use = to separate a named parameter from its default value.

line 43 col 12: Unnecessary new keyword.

line 45 col 40: Unnecessary new keyword.

Fix lib/src/scalar.dart. (-9.08 points)

Analysis of lib/src/scalar.dart reported 19 hints, including:

line 4 col 54: Unnecessary new keyword.

line 8 col 5: Unnecessary new keyword.

line 14 col 5: Unnecessary new keyword.

line 18 col 5: Unnecessary new keyword.

line 21 col 48: Unnecessary new keyword.

Fix lib/src/type.dart. (-5.84 points)

Analysis of lib/src/type.dart reported 12 hints, including:

line 41 col 5: Unnecessary new keyword.

line 71 col 7: DO use curly braces for all flow control structures.

line 71 col 14: Unnecessary new keyword.

line 81 col 9: DO use curly braces for all flow control structures.

line 83 col 9: DO use curly braces for all flow control structures.

Fix additional 6 files with analysis or formatting issues. (-14.30 points)

Additional issues in the following files:

  • lib/src/schema.dart (9 hints)
  • lib/src/enum.dart (7 hints)
  • lib/src/gen.dart (7 hints)
  • lib/src/union.dart (4 hints)
  • lib/src/argument.dart (1 hint)
  • lib/src/field.dart (1 hint)


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.8.0 <3.0.0
collection ^1.0.0 1.14.12
meta ^1.0.0 1.1.8
source_span ^1.0.0 1.6.0
Transitive dependencies
charcode 1.1.3
path 1.6.4
term_glyph 1.1.0
Dev dependencies
test >=0.12.0 <2.0.0