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@globality/nodule-graphql

Node GraphQL Conventions

While GraphQL APIs can be extremely versatile and expressive, there are still good reasons to define multiple such APIs, especially when API consumers have fundamentally different needs, authorization strategies, or resource definitions.

nodule-graphql aims to define conventions for building GraphQL APIs in node so that each such API can focus on its resources and resolvers instead of boilerplate and plumbing.

nodule-graphql achieves these conventions both by providing useful functions for common GraphQL operations and by automatically wiring commmon components into a bottlejs container using the nodule-config library.

Bindings

By importing nodule-graphql, the following bindings are made available.

Middleware

  • middleware.cors injects a CORS middleware with sane caching configuration for OPTIONS headers
  • middleware.helmet injects some sane security-oriented HTTP header defaults
  • middleware.requestId injects a request id into every request

Routes

  • routes.graphql returns a configured GraphQL endpoint
  • routes.graphiql returns a configured GraphiQL endpoint

Utilities

  • terminal injects a colorized terminal writing utility to help with application startup

Resources

nodule-graphql only makes ONE assumption about resource structure: the graphql.schema binding defines a reference to your overall schema:

const { GraphQLObjectType, GraphQLSchema, GraphQLString } = require('graphql');
const { bind } = require('@globality/nodule-config');

bind('graphql.schema', () => new GraphQLSchema({
    query: new GraphQLObjectType({
        name: 'HelloWorld',
        fields: {
            helloWorld: {
                type: GraphQLString,
                resolve: () => 'hello world',
            },
        },
    }),
}));

Routes

nodule-graphql provides default routes (as described above under "Bindings"), enabling very simple wiring of a GraphQL API (assuming graphql.schema is bound):

const bodyParser = require('body-parser');
const { getContainer, Nodule } = require('@globality/nodule-config');
require('@globality/nodule-graphql');

new Nodule({ name: 'hello' }).load().then(() => {
    const { express, graphql } = getContainer('routes');

    express.use(
        '/graphql',
         bodyParser.json(),
         graphql,
    );

    express.listen(8080, '127.0.0.1');
});

Resolvers

Part of the beauty of GraphQL is that resolvers are just functions. However, resolvers can be more than just function and often should be:

  • Resolvers ought to have context for tracing and debugging.

  • Resolvers should be able to perform authorization of requests.

  • Resolvers both aggregate (asynchronously) over sources of truth and translate (synchronously) these results into resources; these actions should be explicit.

Errors

Resolvers should throw errors when something fails. Within nodule-graphql, it is expected that:

  • All errors define code that can be used by API consumers for error handling business logic
  • Most errors will borrow from HTTP error codes (because they have well-known, useful semantics)
  • Error codes should be visible to API consumers via error.extensions

Services

nodule-graphql allows you to wrap your OpenAPI client implementations to add modifications to all defined endpoints.

For usage see the README in the services folder.

Local Development

Local development of nodule-graphql with other repos has a few common pitfalls related to the usage of peer dependencies:

  • nodule-config is a peer-dependency because various libraries act as plugins to it and it needs a single import of bottlejs to share plugin state

  • graphql is a peer-dependency because it validates that all graphql definitions come from the same import and will fail otherwise

To work with nodule-graphql locally:

  1. Run yarn build within nodule-graphql to transpile the source.

  2. Change directories to your local repo that you want to test against nodule-graphql.

  3. Run yarn add /path/to/nodule-graphql to copy the transpiled source into your local repo. Do NOT use yarn link

  4. After running yarn add, remove (or move-of-the-way) the nodule_modules from within nodule_modules/@globality/nodule-graphql/