Directives

See Schema Directives for a detailed explanation about directives including examples on how to define them in the SDL and to create the required classes.

To add your custom SchemaDirectiveWiring to graphql-java-tools pass it along when creating the SchemaParser using

SchemaParser.newParser().directive("name", new MySchemaDirectiveWiring()).build()

Basic usage

Let’s say you defined a custom directive to make text uppercase in a resource schema.graphqls:

directive @uppercase on FIELD_DEFINITION type Query { hello: String @uppercase }

And the actual implementation is the following:

public class UppercaseDirective implements SchemaDirectiveWiring { @Override public GraphQLFieldDefinition onField(SchemaDirectiveWiringEnvironment<GraphQLFieldDefinition> env) { GraphQLFieldDefinition field = env.getElement(); GraphQLFieldsContainer parentType = env.getFieldsContainer(); // build a data fetcher that transforms the given value to uppercase DataFetcher originalFetcher = env.getCodeRegistry().getDataFetcher(parentType, field); DataFetcher dataFetcher = DataFetcherFactories.wrapDataFetcher( originalFetcher, ((dataFetchingEnvironment, value) -> { if (value instanceof String) { return ((String) value).toUpperCase(); } return value; })); // now change the field definition to use the new uppercase data fetcher env.getCodeRegistry().dataFetcher(parentType, field, dataFetcher); return field; } }

Add our custom directive when creating the schema parser:

SchemaParser.newParser() .file("schema.graphqls") .directive("uppercase", new UppercaseDirective()) // ...  .build() .makeExecutableSchema();

Supported locations

Support for directives is currently limited to the following locations:

  • OBJECT
  • FIELD_DEFINITION
  • ARGUMENT_DEFINITION
  • INTERFACE
  • UNION
  • ENUM
  • ENUM_VALUE
  • INPUT_OBJECT
  • INPUT_FIELD_DEFINITION

Meaning directives for the following locations are currently not yet supported:

  • SCALAR