graphql-java: How to add custom scalar type while generating graphql schema programmatically?

Question

I am building a graphql schema using graphql-java. Currently I build all the types programmatically and use the following statement to build the schema:

/* Construct the schema */
GraphQLSchema schema = GraphQLSchema.newSchema()
        .query(query)
        .mutation(mutations)
        .additionalTypes(types)
        .codeRegistry(codeRegistryBuilder.build())
        .build();

I would like to add a custom scalar type for handling JSON objects. All the examples I have seen for adding custom scalar type are using RuntimeWiring. They suggest I should do the following model:

RuntimeWiring buildRuntimeWiring() {
    return RuntimeWiring.newRuntimeWiring()
            .scalar(CustomScalar)

GraphQLSchema schema = new SchemaGenerator().makeExecutableSchema(registry, runtimeWiring);

Since I am not using RuntimeWiring I am wondering how I can add custom scalar type. I would appreciate your help.

Thanks, Rao

Ken Chan Ken Chan · Accepted Answer · 2020-06-13T05:06:55

You can directly instantiate a GraphQLScalarType instance and add it to the additional types in the GraphQL builder :

GraphQLScalarType fooScaler = new GraphQLFooScaler();
types.add(fooScaler);

GraphQLSchema schema = GraphQLSchema.newSchema()
        .query(query)
        .mutation(mutations)
        .additionalTypes(types)
        .codeRegistry(codeRegistryBuilder.build())
        .build();

The SchemaGenerator is only used when you build the schema from GraphQL SDL. If you manually construct the Schema in codes , you do not need it.

graphql-java: How to add custom scalar type while generating graphql schema programmatically?

1 Answers