artemis 2.2.0

Build dart types from GraphQL schemas and queries (using Introspection Query).

Artemis

Build dart types from GraphQL schemas and queries

Artemis is a code generator that looks for schema.json (GraphQL Introspection Query response data) and *.graphql files and builds .dart files typing that query, based on the schema. That's similar to what Apollo does (Artemis is his sister anyway).

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Installation

Add the following to your pubspec.yaml file to be able to do code generation:

dev_dependencies:
  artemis: '>=2.0.0 <3.0.0'
  build_runner: ^1.5.0
  json_serializable: ^3.0.0

The generated code uses the following packages in run-time:

dependencies:
  artemis: '>=2.0.0 <3.0.0' # only if you're using ArtemisClient!
  json_serializable: ^3.0.0
  equatable: ^0.6.1
  gql: '>=0.7.3 <1.0.0'

Then run:

pub packages get

or

flutter packages get

Now Artemis will generate the API files for you by running:

pub run build_runner build

or

flutter pub run build_runner build

Configuration

Artemis offers some configuration options to generate code. All options should be included on build.yaml file on the root of the project:

targets:
  $default:
    builders:
      artemis:
        options:
          # custom configuration options!

Option	Default value	Description
generate_helpers	true	If Artemis should generate query/mutation helper GraphQLQuery subclasses.
custom_parser_import	null	Import path to the file implementing coercer functions for custom scalars. See Custom scalars.
scalar_mapping	[]	Mapping of GraphQL and Dart types. See Custom scalars.
schema_mapping	[]	Mapping of queries and which schemas they will use for code generation. See Schema mapping.
fragments_glob	null	Import path to the file implementing fragments for all queries mapped in schema_mapping. If it's assigned, fragments defined in schema_mapping will be ignored.

It's important to remember that, by default, build will follow Dart's package layout conventions, meaning that only some folders will be considered to parse the input files. So, if you want to reference files from a folder other than lib/, make sure you've included it on sources:

targets:
  $default:
    sources:
      - lib/**
      - graphql/**
      - data/**
      - schema.json

Schema mapping

By default, Artemis won't generate anything. That's because your queries/mutations should be linked to GraphQL schemas. To configure it, you need to point a schema_mapping to the path of those queries and schemas:

targets:
  $default:
    builders:
      artemis:
        options:
          schema_mapping:
            - output: lib/graphql_api.dart
              schema: lib/my_graphql_schema.json
              queries_glob: lib/**.graphql

Each SchemaMap is configured this way:

Option	Default value	Description
output		Relative path to output the generated code.
schema		Relative path to the GraphQL schema.
queries_glob		Glob that selects all query files to be used with this schema.
resolve_type_field	__resolveType	The name of the field used to differentiatiate interfaces and union types (commonly __resolveType or __typename). Note that __resolveType field are not added automatically to the query. If you want interface/union type resolution, you need to manually add it to the query.
add_query_prefix	false	Wheter to add the name of the query as a prefix for each dependent object of this query input or response.

See examples for more information and configuration options.

Custom scalars

If your schema uses custom scalars, they must be defined on build.yaml. If it needs a custom parser (to decode from/to json), the custom_parser_import path must be set and the file must implement both fromGraphQL___ToDart___ and fromDart___toGraphQL___ constant functions.

targets:
  $default:
    builders:
      artemis:
        options:
          custom_parser_import: 'package:graphbrainz_example/coercers.dart'
          scalar_mapping:
            - graphql_type: Date
              dart_type: DateTime

If your custom scalar needs to import Dart libraries, you can provide it in the config as well:

targets:
  $default:
    builders:
      artemis:
        options:
          custom_parser_import: 'package:graphbrainz_example/coercers.dart'
          scalar_mapping:
            - graphql_type: BigDecimal
              dart_type:
                name: Decimal
                imports:
                  - 'package:decimal/decimal.dart'

Each ScalarMap is configured this way:

Option	Default value	Description
graphql_type		The GraphQL custom scalar name on schema.
dart_type		The Dart type this custom scalar should be converted from/to.
use_custom_parser	false	Wheter custom_parser_import should be imported on the beginning of the file.

See examples for more information and configuration options.

ArtemisClient

If you have generate_helpers, Artemis will create a subclass of GraphQLQuery for you, this class can be used in conjunction with ArtemisClient.

final client = ArtemisClient('/graphql');
final gitHubReposQuery = MyGitHubReposQuery();
final response = await client.execute(gitHubReposQuery);

ArtemisClient adds type-awareness around Link from package:gql/link. You can create ArtemisClient from any Link using ArtemisClient.fromLink.

Check the examples to see how to use it in details.