Why and How You Should Create a GraphQL API with Ruby on Rails in 2025

This article provides a comprehensive guide to creating a GraphQL API with Ruby on Rails, one of the vital skills when working with Ruby. It covers the advantages of using GraphQL with Rails, setting up a new Rails API project, writing GraphQL queries, and exploring key concepts such as schemas, types, queries, mutations, and resolvers. Additionally, it delves into the differences between GraphQL and REST APIs, highlighting when to choose one over the other.

What Is GraphQL ?

GraphQL provides a powerful and efficient way to build APIs with Ruby on Rails. Its advantages, such as efficient data fetching, a single endpoint, and strong typing, make it a compelling alternative to REST APIs for many use cases. GraphQL was created by Facebook to address the limitations of REST APIs and provide a more flexible and efficient way to fetch data.

Companies like GitHub and Shopify utilize GraphQL in their Rails applications to power various features and services. By understanding the key concepts of GraphQL and leveraging the available tools and resources, such as the graphql-ruby gem, GraphiQL IDE, and open-source projects like artemis and rails-graphql-realworld-example-app, you can create robust and scalable APIs that meet the needs of your applications.

Why You Should Use GraphQL with Ruby on Rails

GraphQL offers several advantages over traditional REST APIs, especially when used with Ruby on Rails:

1. Efficient Data Fetching:

Clients can request exactly the data they need, reducing over-fetching and improving performance. This leads to faster load times and a better user experience, especially on mobile devices with limited bandwidth:

In a REST API, fetching a blog post might require one endpoint for the post and another for its comments. With GraphQL, a single query can fetch both the post and its comments in one request:

query {
    post(id: 1) {
        title
        content
        comments {
    author
    message
   }
  }
}

This reduces the number of network requests and avoids over-fetching or under-fetching data.

2. Single Endpoint:

GraphQL uses a single endpoint for all queries and mutations, simplifying client-side development.

Instead of managing multiple endpoints (e.g., /posts, /users, /comments), GraphQL uses a single /graphql endpoint. Clients specify their needs in the query:

graphql
 query {
  user(id: 1) {
    name
    posts {
      title
    }
  }
}

This simplifies client-side development and API management

3. Strong Typing:

GraphQL’s strong type system ensures data consistency and facilitates debugging. By defining the type of each attribute, you can prevent errors and make it easier to identify and resolve issues. This also contributes to a better developer experience by providing clear expectations and reducing ambiguity.

A GraphQL schema defines types like this:

ruby
class Types::PostType < Types::BaseObject
  field :id, ID, null: false
  field :title, String, null: false
  field :content, String, null: true
  field :author, Types::UserType, null: false
end

This ensures that any query or mutation adheres to the schema, reducing runtime errors and improving debugging.

4. No Versioning:

GraphQL allows for schema evolution without breaking existing clients. You can add new fields and types or deprecate old ones without affecting existing queries, making it easier to maintain and update your API over time.

If you need to add a new field (likes) to posts, simply update the schema:

ruby

field :likes, Integer, null: true

5. Rapid Product Development:

GraphQL promotes rapid product development by allowing for flexible changes on the client-side without requiring backend adjustments. This decoupling of frontend and backend development allows for faster iteration and more agile development processes.

Frontend developers can build features without waiting for backend changes. For instance:

• Backend provides a generic post query.
• Frontend decides to display likes and comments without requiring backend modifications since these fields are already in the schema

6. Improved Developer Experience:

GraphQL provides a more efficient and intuitive way to work with data, improving the overall developer experience. By giving developers more control over data fetching and manipulation, GraphQL streamlines development workflows and reduces complexity.

Tools like GraphiQL or Apollo Studio make it easy to test queries and explore schemas:

• Developers can use an interface to write queries like:

query {
  posts {
    title
    author {
      name
    }
  }
}

Setting Up a New Rails API Project

To start building a GraphQL API with Ruby on Rails, follow these steps:

1. Create a new Rails project: Use the following command to create a new Rails API project with PostgreSQL as the database:
   Bash
rails new rails-graphql --api -d postgresql
cd rails-graphql
   
2. Add the GraphQL gem: Include the graphql gem in your Gemfile:
   Ruby
   gem 'graphql'

3. Install dependencies: Run bundle install to install the required gems.
4. Generate GraphQL installation files: Use the following command to generate the necessary GraphQL files and directories:
   Bash
   rails generate graphql:install

   This command utilizes a Rails generator to automate the process of creating files with boilerplate code for GraphQL integration.
5. Set up GraphiQL IDE: To access the GraphiQL IDE in your browser, you’ll need to make a few adjustments to your Rails application. First, add require “sprockets/railtie” to your application.rb file. Then, create an app/assets/config/manifest.js file with the following content:
   JavaScript
   //= link_tree ../images
//= link_directory ../javascripts .js
//= link_directory ../stylesheets .css
//= link graphiql/rails/application.css
//= link graphiql/rails/application.js
   
   This setup allows you to use the GraphiQL IDE, a handy web interface for testing GraphQL queries and mutations within your browser.

Writing Your First GraphQL Query

GraphQL queries are a powerful way to retrieve specific data from an API. Here’s a deeper dive into how to write and understand your first GraphQL query.

1. Basic Structure of a GraphQL Query

A GraphQL query consists of:

1. Root Field: The entry point for the data you want (e.g., posts).
2. Fields: Specific pieces of data requested from the root field (e.g., id, title, description).

For example:

graphql
query {
  posts {
    id
    title
    description
  }
}

• Root Field: posts (represents all posts).
• Fields: id, title, and description.

This query tells the server to return only the specified fields for all posts, avoiding over-fetching or under-fetching data.

2 Response Format

The server responds in JSON format, matching the structure of the query:

json{
  "data": {
    "posts": [
      {
        "id": "1",
        "title": "GraphQL Basics",
        "description": "Learn how to write GraphQL queries."
      },
      {
        "id": "2",
        "title": "Advanced GraphQL",
        "description": "Explore advanced GraphQL features."
      }
    ]
  }
}

This symmetry between query and response improves readability and predictability.

3. Named Queries

While the above example is an anonymous query, you can name your queries for better clarity and debugging:

graphql
query GetPosts {
  posts {
    id
    title
    description
  }
}

Naming queries is especially useful when working with tools like Apollo Client or when debugging logs.

4. Adding Arguments

GraphQL allows you to filter or customize data by passing arguments to fields. For instance:

graphql
query {
  post(id: 1) {
    title
    description
  }
}

Here, the post field accepts an argument (id: 1) to fetch a specific post.

5. Variables in Queries

To make queries reusable, you can use variables. For example:

graphql
query GetPost($id: ID!) {
  post(id: $id) {
    title
    description
  }
}

When executing this query, you provide the variable value separately:

json{
  "id": 1
}

6. Nested Queries

GraphQL supports nested queries, allowing you to fetch related data in one request:

graphql
query {
  post(id: 1) {
    title
    description
    author {
      name
      email
    }
  }
}

This retrieves both the post details and its author’s information, reducing the need for multiple API calls.

7. Aliases

Aliases allow renaming fields in the response, useful when querying the same field multiple times with different arguments:

graphql
query {
  firstPost: post(id: 1) {
    title
  }
  secondPost: post(id: 2) {
    title
  }
}

Response:

json{
  "data": {
    "firstPost": { "title": "GraphQL Basics" },
    "secondPost": { "title": "Advanced GraphQL" }
  }
}

8 Fragments for Reusability

Fragments help reuse field selections across queries:

graphql
fragment PostDetails on Post {
  title
  description
}

query {
  posts {
    ...PostDetails
  }
}

By understanding these concepts, you can write efficient, precise, and reusable GraphQL queries tailored to your application’s needs.

GraphQL vs REST API: Which One Is Better With Ruby on Rails?

While both GraphQL and REST are popular API architectures, they differ in several key aspects:

For example, imagine fetching user data. In REST, you might have separate endpoints for /users and /users/:id/posts. To get a user’s posts, you’d first need to fetch the user’s data, then make another request to the posts endpoint with the user’s ID. With GraphQL, you could fetch both the user and their posts in a single query:

GraphQL

query {
  user(id: 123) {
    name
    posts {
      title
    }
  }
}
This illustrates how GraphQL can reduce over-fetching by allowing clients to specify exactly what data they need.

GraphQL is generally preferred when:

• Bandwidth is limited, and minimizing requests is crucial.
• Data needs to be aggregated from multiple sources.
• Client requests vary significantly.

4 Key GraphQL Concepts For Every Software Developers

1. Schemas and Types

The schema is the backbone of any GraphQL API. It defines the structure of the data that can be queried or mutated, as well as the relationships between different data types. In essence, it acts as a contract between the client and server, ensuring that only valid operations are performed.

Scalar Types: Represent primitive data values such as String, Int, Float, Boolean, and ID. These are the building blocks of your schema and cannot have subfields. For example:

graphql
type Query {
userName: String
age: Int
}

Object Types: Define complex entities with multiple fields. For example:

type Post {
  id: ID!
  title: String!
  content: String
  comments: [Comment]
}

Other Types:

• Input Types: Used for passing structured data into mutations.
• Enums: Represent a set of predefined values (e.g., status codes).
• Interfaces and Unions: Enable polymorphism by allowing a field to return one of several object types.

2. Queries

Queries are used to fetch data from the server. Unlike REST APIs where you query specific endpoints for specific resources, GraphQL uses a single endpoint where clients specify exactly what data they need.

Basic Query Example:

graphql
query { posts { id title content } }

This query retrieves all posts with their id, title, and content.

Nested Queries:
GraphQL allows querying related data in one request. For example:

graphql
 query { 
  posts { 
  title 
  comments { 
     author 
     message 
   } 
  } 
 }

This fetches posts along with their associated comments.

Arguments in Queries:
You can pass arguments to filter or customize the data. For instance:

graphql

query { 
  post(id: "1") { 
    title content 
  } 
} 

Here, only the post with an ID of “1” is retrieved.

3. Mutations

Mutations are used to modify server-side data, such as creating, updating, or deleting records. They correspond to actions like POST, PUT, or DELETE in REST APIs but are more flexible because they allow you to specify exactly what data should be returned after the operation.

Input Types for Mutations: Input types allow passing structured arguments to mutations. For example:

input CreatePostInput {
  title: String!
  content: String!
}

type Mutation {
  createPost(input: CreatePostInput): Post!
}

4. Resolvers

Resolvers are functions that handle fetching or modifying data for each field in your schema. They connect your GraphQL API to your underlying data sources (e.g., databases or external APIs).

For a query like this:

query {
  posts {
    id
    title
  }
}

You would define a resolver method in your Rails application to fetch the posts:

module Resolvers
  class PostsResolver < GraphQL::Schema::Resolver
    type [Types::PostType], null: false

    def resolve
      Post.all # Fetches all posts from the database.
    end
  end
end

# Schema definition using the resolver:
class Types::QueryType < Types::BaseObject
  field :posts, [Types::PostType], null: false, 
resolver: Resolvers::PostsResolver
end

Field-Level Resolvers:
Each field in an object type can have its own resolver. For example, if fetching comments for a post requires additional logic (like filtering), you can define a custom resolver for the comments field.

Summary Table of Concepts

These concepts form the foundation of building flexible and efficient APIs with GraphQL!

Types of GraphQL APIs

GraphQL provides three main types of operations for interacting with APIs:

• Queries: Used for fetching data. Similar to GET requests in REST.
• Mutations: Used for modifying data (creating, updating, or deleting). Similar to POST, PUT, and DELETE requests in REST.
• Subscriptions: Used for receiving real-time updates when data changes. This allows for functionalities like live chat or real-time notifications.

GraphQL Best Practices

When designing and implementing your GraphQL API, consider these best practices:

• Ensure naming consistency in the schema: Use clear and consistent naming conventions for fields, types, and other elements in your schema to improve readability and maintainability.
• Consider future modifications to the schema: Design your schema with flexibility in mind to accommodate future changes and additions without requiring major overhauls.
• Eliminate illogical fragments: Use fragments judiciously to avoid unnecessary complexity and ensure that they contribute to code clarity and reusability.
• Avoid hard-coded arguments: Use variables for arguments to improve security, caching, and maintainability.
• Establish an error handling plan: Implement robust error handling to provide informative error messages and ensure graceful recovery from unexpected situations.

Open-Source Projects on GitHub

Several open-source projects on GitHub utilize Ruby on Rails and GraphQL:

• graphql-ruby: A Ruby implementation of the GraphQL specification. This gem provides the foundation for building GraphQL APIs in Ruby.
• artemis: A Ruby GraphQL client for Rails. This gem simplifies making GraphQL requests from your Rails application.
• rails-graphql-realworld-example-app: An exemplary real-world backend GraphQL API built with Ruby on Rails. This project provides a practical example of how to implement a GraphQL API in a real-world scenario.

Conclusion

Creating a GraphQL API with Ruby on Rails means providing developers with a more efficient, flexible way to manage and query data. By choosing GraphQL, developers can precisely request the data they need, reducing over-fetching and under-fetching of data. Rails, known for its robust and developer-friendly framework, makes the process of setting up a GraphQL API smooth and efficient. This combination enhances performance, improves developer productivity, and offers a better user experience.

For Vinova’s web developers, combining GraphQL with Ruby on Rails was a game changers in our work process with Ruby.

Stay tuned for more information on must know tips and tricks with Ruby on Rails, from Vinova, one of the fastest growing IT solutions in Singapore.