When building a GraphQL server in JavaScript, it’s essential to ensure that your application has proper user roles and permissions. This allows you to control access to specific resources and restrict certain actions based on the user’s role or permissions.

In this blog post, we will explore how to implement user roles and permissions in a JavaScript GraphQL server using a popular library called graphql-shield.

Introduction to graphql-shield

graphql-shield is a powerful library that provides an easy way to implement authorization rules in a GraphQL server. It integrates seamlessly with the popular JavaScript GraphQL libraries like Apollo Server and graphql-yoga.

Installing Dependencies

Let’s start by installing the necessary dependencies for our project:

$ npm install graphql graphql-shield

Defining User Roles

User roles are defined based on the access level they have within the application. Common roles include admin, user, or guest. You can define custom roles based on the needs of your application.

To define user roles with graphql-shield, you need to create a new file called permissions.js and import the necessary functions from graphql-shield. Let’s take a look:

// permissions.js

import { rule, shield } from 'graphql-shield';

const isAuthenticated = rule()((parent, args, { user }) => {
  return user !== null;
});

const isAdmin = rule()(async (parent, args, { user }) => {
  // Perform a database lookup or any other logic to determine if the user has admin access
});

export const permissions = shield({
  Query: {
    // Define read permissions here
  },
  Mutation: {
    // Define write permissions here
  },
});

In the code snippet above, we define two rules using the rule function provided by graphql-shield. The isAuthenticated rule checks if the user is authenticated, while the isAdmin rule checks if the user has admin access. You can add additional rules based on your application’s requirements.

Implementing Permissions

After defining the user roles, you can now implement the permissions in your resolvers. Let’s take an example of a simple GraphQL resolver for creating a new blog post:

// resolvers.js

import { permissions } from './permissions';

const resolvers = {
  Mutation: {
    createBlogPost: (_, { input }, { user }) => {
      // Check if the user has the necessary permissions to create a blog post
      permissions.Mutation.createBlogPost(user);

      // Perform the creation logic here
    },
  },
};

In the code snippet above, we import the permissions object defined in the permissions.js file and use it to check if the user has the necessary permissions to create a new blog post. If the user doesn’t have the required permissions, an error will be thrown, preventing the creation of the blog post.

Securing Your GraphQL Server

To secure your GraphQL server with the implemented user roles and permissions, you need to integrate graphql-shield with your GraphQL server. Here’s an example of how you can integrate it with Apollo Server:

// server.js

import { ApolloServer } from 'apollo-server';
import { applyMiddleware } from 'graphql-middleware';
import { permissions } from './permissions';
import { typeDefs, resolvers } from './schema';

const server = new ApolloServer({
  typeDefs,
  resolvers: applyMiddleware(permissions)(resolvers),
});

server.listen().then(({ url }) => {
  console.log(`Server running at ${url}`);
});

In the code snippet above, we use the applyMiddleware function from graphql-middleware to apply the permissions middleware to the Apollo Server. This ensures that the permissions defined in the permissions.js file are enforced for every GraphQL operation.

Conclusion

Implementing user roles and permissions is a critical aspect of building secure and scalable JavaScript GraphQL servers. With the help of graphql-shield, you can easily define and enforce these permissions in your application.

Remember to define user roles based on the access levels required for your application, implement the necessary rules and permissions, and integrate graphql-shield with your GraphQL server.

#javascript #GraphQL #UserRoles #Permissions