graphql-transformer

graphql-transformer

A tool to transform GraphQL schemas via simple functions

How to use

npm install --save graphql-transformer

Basic usage:

const transformedSchema = transformSchema(originalSchema, {
    transformField(field: GraphQLNamedFieldConfig<any, any>, context) {
        // Rename a field in a type
        if (context.oldOuterType.name == 'MyType') {
            return {
                ...field,
                name: field.name + 'ButCooler'
            }
        }
        return field;
    },

    transformObjectType(type: GraphQLObjectTypeConfig<any, any>) {
        if (type.name == 'MyType') {
            return {
                ...type,
                name: 'MyCoolType'
            };
        }
        return type;
    },

    transformFields(fields: GraphQLFieldConfigMap<any, any>, context) {
        // You can even copy types on the fly and transform the copies
        const type2 = context.copyType(context.oldOuterType, {
            transformObjectType(typeConfig: GraphQLObjectTypeConfig<any, any>) {
                return {
                    ...typeConfig,
                    name: typeConfig.name + '2'
                };
            }
        });

        // This just adds a reflexive field "self" to all types, but its type does not have
        // the "self" field (because it is a copy from the original type, see above)
        // it also won't have the "cool" rename applied because the top-level transformers are not applied
        return {
            ...fields,
            self: {
                type: type2,
                resolve: (source: any) => source
            }
        }
    }
});

This test case demonstrates that and how it works.

Contributing

After cloning the repository, run

npm install
npm start

To run the test suite, run

npm test

To debug the tests in WebStorm, right-click on graphql-transformer-test.js and choose Debug.