Mutation

G.apex treats query and mutation similarly. We can define our mutation operations in the schema, and process the requests in the resolving functions.

G.Schema schema = new G.Schema()
    .add(
        new G.ObjectType('mutation')
            .addField('addBook', bookType, new AddBookResolver())
                .addParam('addBook', 'name', G.StringType, R.isNotNull)
    );

We add a parameter definition name of String type to the field addBook. Also this parameter has a validation of not-null specified by the R.isNotNull Func.