Exploring Directus GraphQL

Directus is an open-source headless CMS (Content Management System) that provides a useful interface for managing and delivering content to various channels. With the introduction of Directus GraphQL, developers have a new way to interact with and consume data from Directus APIs. In this article, we will explore the various aspects of Directus GraphQL and how it can be leveraged in programming.

Schema Stitching in Directus GraphQL

Schema stitching is a technique that allows multiple GraphQL schemas to be combined into a single schema. In the context of Directus GraphQL, schema stitching can be used to integrate Directus with other GraphQL APIs or to combine multiple Directus projects into a unified schema.

Here is an example of how schema stitching can be implemented in Directus GraphQL using the graphql-tools library:

const { stitchSchemas } = require('@graphql-tools/stitch');

const schema1 = require('./schema1');
const schema2 = require('./schema2');

const stitchedSchema = stitchSchemas({
  schemas: [schema1, schema2],
});

In this example, schema1 and schema2 represent the individual schemas that need to be stitched together. The stitchSchemas function from the @graphql-tools/stitch library is used to combine these schemas into a single schema called stitchedSchema.

Related Article: Implementing TypeORM with GraphQL and NestJS

The Role of Apollo Client in Directus GraphQL

Apollo Client is a useful GraphQL client that provides a seamless way to interact with GraphQL APIs. In the context of Directus GraphQL, Apollo Client can be used to fetch data from Directus APIs, perform mutations, and subscribe to real-time updates.

To use Apollo Client with Directus GraphQL, you need to create an instance of Apollo Client and configure it to connect to your Directus GraphQL endpoint. Here is an example of how to set up Apollo Client with Directus GraphQL:

import { ApolloClient, InMemoryCache } from '@apollo/client';

const client = new ApolloClient({
  uri: 'https://directus.example.com/graphql',
  cache: new InMemoryCache(),
});

In this example, the ApolloClient class is imported from the @apollo/client package. The uri option is set to the Directus GraphQL endpoint, and the cache option is set to an instance of InMemoryCache, which is the default cache implementation provided by Apollo Client.

How GraphQL Subscriptions Work in Directus GraphQL

GraphQL subscriptions allow clients to receive real-time updates from a GraphQL API. In the context of Directus GraphQL, subscriptions can be used to listen for changes to data in the Directus database and receive updates in real-time.

Directus GraphQL uses the PubSub class from the graphql-subscriptions library to implement subscriptions. Here is an example of how to set up a subscription in Directus GraphQL:

import { PubSub } from 'graphql-subscriptions';

const pubsub = new PubSub();

const Subscription = {
  commentAdded: {
    subscribe: () => pubsub.asyncIterator('COMMENT_ADDED'),
  },
};

const resolvers = {
  Subscription,
};

In this example, the PubSub class is imported from the graphql-subscriptions package. An instance of PubSub is created, and a subscription resolver called commentAdded is defined. The subscribe function returns an AsyncIterator that listens for events with the COMMENT_ADDED topic.

Writing GraphQL Mutations in Directus

GraphQL mutations allow clients to modify data in a GraphQL API. In the context of Directus GraphQL, mutations can be used to create, update, and delete records in the Directus database.

Here is an example of how to write a mutation in Directus GraphQL:

mutation {
  createPost(input: {
    title: "New Post",
    content: "Lorem ipsum dolor sit amet"
  }) {
    id
    title
    content
  }
}

In this example, a createPost mutation is defined with an input argument that contains the data for creating a new post. The mutation returns the id, title, and content fields of the newly created post.

Related Article: Working with GraphQL Enums: Values Explained

Defining Resolvers in Directus GraphQL

Resolvers are functions that resolve the data for a GraphQL query or mutation. In the context of Directus GraphQL, resolvers can be used to fetch data from the Directus database, perform transformations, and return the requested data to the client.

Here is an example of how to define resolvers in Directus GraphQL:

const resolvers = {
  Query: {
    posts: async () => {
      // Fetch posts from the Directus database
      const response = await fetch('https://directus.example.com/api/1.1/tables/posts/rows');
      const data = await response.json();
      
      // Return the posts
      return data;
    },
  },
};

In this example, a resolver is defined for the posts field in the Query type. The resolver uses the fetch function to fetch the posts from the Directus database and returns the fetched data.

Understanding GraphQL Introspection in Directus

GraphQL introspection allows clients to fetch the schema of a GraphQL API. In the context of Directus GraphQL, introspection can be used to discover the available types, fields, and directives in the Directus schema.

To enable introspection in Directus GraphQL, you need to set the introspection option to true in the Directus configuration file. Here is an example of how to enable introspection in Directus:

module.exports = {
  // Other Directus configuration options
  introspection: true,
};

With introspection enabled, clients can use tools like GraphiQL or GraphQL Playground to explore the Directus schema and execute queries against the API.

Using GraphQL Directives in Directus

GraphQL directives are used to add additional functionality to the schema. In the context of Directus GraphQL, directives can be used to apply custom logic or transformations to fields, arguments, or entire queries/mutations.

Here is an example of how to define and use a directive in Directus GraphQL:

directive @uppercase on FIELD_DEFINITION

type Query {
  hello: String @uppercase
}

schema {
  query: Query
}

In this example, a custom directive called uppercase is defined using the @uppercase syntax. The directive is applied to the hello field in the Query type, which transforms the returned string to uppercase.

Leveraging GraphQL Fragments in Directus

GraphQL fragments allow clients to define reusable selections of fields that can be included in multiple queries or mutations. In the context of Directus GraphQL, fragments can be used to define common sets of fields that are frequently requested.

Here is an example of how to define and use a fragment in Directus GraphQL:

fragment PostFields on Post {
  id
  title
  content
}

query {
  post(id: 1) {
    ...PostFields
  }
}

In this example, a fragment called PostFields is defined with the id, title, and content fields of the Post type. The fragment is then included in a query for a specific post, which allows the selected fields to be reused in multiple queries.

Related Article: Implementing Upsert Operation in GraphQL

Defining a GraphQL Schema in Directus

A GraphQL schema defines the types, fields, and directives available in a GraphQL API. In the context of Directus GraphQL, a schema can be defined using the Directus schema builder or by writing the schema definition language (SDL) directly.

Here is an example of how to define a schema in Directus using the Directus schema builder:

const schema = new SchemaBuilder()
  .createObjectType('Post')
  .addFields({
    id: 'ID',
    title: 'String',
    content: 'String',
  })
  .build();

In this example, a schema builder instance is created using the SchemaBuilder class. An object type called Post is defined with the id, title, and content fields. The schema is then built using the build method.

Understanding GraphQL Scalars in Directus

GraphQL scalars are the basic building blocks of a GraphQL schema and represent primitive data types like strings, integers, booleans, and floats. In the context of Directus GraphQL, scalars can be used to define the types of fields in the Directus schema.

Here is an example of how to define a scalar in Directus GraphQL:

scalar Date

type Post {
  id: ID
  title: String
  createdAt: Date
}

In this example, a scalar called Date is defined. The Date scalar can be used as the type for the createdAt field in the Post type, allowing dates to be represented in the Directus schema.

Additional Resources

- Introduction to GraphQL

- What is an API? - MDN Web Docs