This is a GraphQL Java implementation based on the specification and the JavaScript reference implementation.
Status: Version 2.0.0 is released.
The versioning follows Semantic Versioning since 2.0.0.
Hint: This README documents the latest release, but master contains the current development version. So please make sure
to checkout the appropriate tag when looking for the version documented here.
- Overview
- Code of Conduct
- Mailing List
- Hello World
- Getting started
- Manual
- Contributions
- Build it
- Development Build
- Details
- Acknowledgment
- Related Projects
- License
This is a Java Implementation of GraphQL. The library aims for real-life usage in production.
It takes care of parsing and executing a GraphQL query. It doesn't take care of actually fetching any data: Data comes from implementing callbacks or providing static data.
Please note that this project is released with a Contributor Code of Conduct. By contributing to this project (commenting or opening PR/Issues etc) you are agreeing to follow this conduct, so please take the time to read it.
If you have a question or want to discuss anything else related to this project:
There is a mailing list (Google Group) for graphql-java: graphql-java group
This is the famous "hello world" in graphql-java:
import graphql.schema.GraphQLObjectType;
import graphql.schema.GraphQLSchema;
import static graphql.Scalars.GraphQLString;
import static graphql.schema.GraphQLFieldDefinition.newFieldDefinition;
import static graphql.schema.GraphQLObjectType.newObject;
public class HelloWorld {
public static void main(String[] args) {
GraphQLObjectType queryType = newObject()
.name("helloWorldQuery")
.field(newFieldDefinition()
.type(GraphQLString)
.name("hello")
.staticValue("world")
.build())
.build();
GraphQLSchema schema = GraphQLSchema.newSchema()
.query(queryType)
.build();
Map<String, Object> result = new GraphQL(schema).execute("{hello}").getData();
System.out.println(result);
// Prints: {hello=world}
}
}Make sure mavenCentral is among your repos:
repositories {
mavenCentral()
}
Dependency:
dependencies {
compile 'com.graphql-java:graphql-java:2.0.0'
}
Dependency:
<dependency>
<groupId>com.graphql-java</groupId>
<artifactId>graphql-java</artifactId>
<version>2.0.0</version>
</dependency>
The Scalars Class has the following built-in types:
GraphQLStringGraphQLBooleanGraphQLIntGraphQLFloat
Example:
GraphQLObjectType simpsonCharacter = newObject()
.name("SimpsonCharacter")
.description("A Simpson character")
.field(newFieldDefinition()
.name("name")
.description("The name of the character.")
.type(GraphQLString)
.build())
.field(newFieldDefinition()
.name("mainCharacter")
.description("One of the main Simpson characters?")
.type(GraphQLBoolean)
.build())
.build();Example:
GraphQLInterfaceType comicCharacter = newInterface()
.name("ComicCharacter")
.description("A abstract comic character.")
.field(newFieldDefinition()
.name("name")
.description("The name of the character.")
.type(GraphQLString)
.build())
.build();Example: (a snippet from here)
GraphQLUnionType PetType = newUnionType()
.name("Pet")
.possibleType(CatType)
.possibleType(DogType)
.typeResolver(new TypeResolver() {
@Override
public GraphQLObjectType getType(Object object) {
if (object instanceof Cat) {
return CatType;
}
if (object instanceof Dog) {
return DogType;
}
return null;
}
})
.build();
Example:
GraphQLEnumType colorEnum = newEnum()
.name("Color")
.description("Supported colors.")
.value("RED")
.value("GREEN")
.value("BLUE")
.build();
Example:
GraphQLInputObjectType inputObjectType = newInputObject()
.name("inputObjectType")
.field(newInputObjectField()
.name("field")
.type(GraphQLString)
.build())
.build()GraphQLList and GraphQLNonNull wrap another type to declare a list or to forbid null values.
There are no builders to create now objects. Just normal constructors, because they are so simple.
Example:
new GraphQLList(GraphQLString); // a list of Strings
new GraphQLNonNull(GraphQLString); // a non null StringExample:
GraphQLSchema schema = GraphQLSchema.newSchema()
.query(queryType) // must be provided
.mutation(mutationType) // is optional
.build();
A full schema example: StarWarsSchema
Another schema example, including union types: GarfieldSchema
GraphQL supports recursive Types: For example a Person can contain a list of friends of the same Type.
To be able to declare such a Type, graphql-java has a GraphQLTypeReference class.
When the schema is created, the GraphQLTypeReference is replaced with the actual real Type Object.
For example:
GraphQLObjectType person = newObject()
.name("Person")
.field(newFieldDefinition()
.name("friends")
.type(new GraphQLList(new GraphQLTypeReference("Person")))
.build())
.build();The actual data comes from DataFetcher objects.
Every field definition has a
8000
DataFetcher. When no one is configured, a
PropertyDataFetcher is used.
PropertyDataFetcher fetches data from Map and Java Beans. So when the field name matches the Map key or
the property name of the source Object, no DataFetcher is needed.
Example of configuring a custom DataFetcher:
DataFetcher calculateComplicatedValue = new DataFetcher() {
@Override
Object get(DataFetchingEnvironment environment) {
// environment.getSource() is the value of the surrounding
// object. In this case described by objectType
Object value = ... // Perhaps getting from a DB or whatever
return value;
}
GraphQLObjectType objectType = newObject()
.name("ObjectType")
.field(newFieldDefinition()
.name("someComplicatedValue")
.type(GraphQLString)
.dataFetcher(calculateComplicatedValue)
.build())
.build();To execute a Query/Mutation against a Schema instantiate a new GraphQL Object with the appropriate arguments and then call execute().
The result of a Query is a ExecutionResult Object with the result and/or a list of Errors.
Example: GraphQL Test
Complexer examples: StarWars query tests
All fields in a SelectionSet are executed serially per default.
GraphQL takes as second constructor argument an optional ExecutorService.
When provided fields will be executed parallel, except the first level of a mutation operation.
See specification for details.
It's recommended to use a ExecutorService to speed up execution.
Alternatively, schemas with nested lists may benefit from using a BatchedExecutionStrategy and creating batched DataFetchers with get() methods annotated @Batched.
Logging is done with SLF4J. Please have a look at the Manual for details.
The grapqhl-java root Logger name is graphql.
There is a very basic Relay support included. Please look at https://github.com/andimarek/todomvc-relay-java for an example project how to use it.
Every contribution to make this project better is welcome: Thank you!
In order to make this a pleasant as possible for everybody involved, here are some tips:
- Respect the Code of Conduct
- Before opening an Issue to report a bug, please try the latest development version. It can happen that the problem is already solved.
- Please use Markdown to format your comments properly. If you are not familiar with that: Getting started with writing and formatting on GitHub
- For Pull Requests:
- Here are some general tips
- Please be a as focused and clear as possible and don't mix concerns. This includes refactorings mixed with bug-fixes/features, see Open Source Contribution Etiquette
- It would be good to add a automatic test. All tests are written in Spock.
The latest development build is available on Bintray.
Please look at Latest Build for the latest version value.
Add the repositories:
repositories {
mavenCentral()
maven { url "http://dl.bintray.com/andimarek/graphql-java" }
}
Dependency:
dependencies {
compile 'com.graphql-java:graphql-java:INSERT_LATEST_VERSION_HERE'
}
Add the repository:
<repository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>bintray-andimarek-graphql-java</id>
<name>bintray</name>
<url>http://dl.bintray.com/andimarek/graphql-java</url>
</repository>
Dependency:
<dependency>
<groupId>com.graphql-java</groupId>
<artifactId>graphql-java</artifactId>
<version>INSERT_LATEST_VERSION_HERE</version>
</dependency>
Just clone the repo and type
./gradlew buildIn build/libs you will find the jar file.
Running the tests:
./gradlew testInstalling in the local Maven repository:
./gradlew installThe implementation is in Java 6, but the tests are in Groovy and Spock.
The query parsing is done with ANTLR. The grammar is here.
The only runtime dependencies are ANTLR and Slf4J.
This implementation is based on the js reference implementation. For example the StarWarSchema and the tests (among a lot of other things) are simply adapted to the Java world.
graphql-rxjava: An execution strategy that makes it easier to use rxjava's Observable
graphql-java-annotations: Annotations-based syntax for GraphQL schema definition.
graphql-java-servlet: Servlet that automatically exposes a schema dynamically built from GraphQL queries and mutations.
graphql-java is licensed under the MIT License. See LICENSE for details.
Copyright (c) 2015, Andreas Marek and Contributors