GraphQL | Benefits and Drawbacks | How to use graphql in ruby on rails

            GraphQL is an open-source query language and runtime for APIs (Application Programming Interfaces). It was developed by Facebook in 2012 and has since become increasingly popular as an alternative to traditional REST APIs. GraphQL provides a more efficient, powerful, and flexible way to query and manipulate data from APIs.

        In this blog, we will take a detailed look at what GraphQL is, how it works, and its benefits and drawbacks.

What is GraphQL?

        GraphQL is a query language that allows clients to request only the data they need, and nothing more. In a traditional REST API, clients make requests for specific resources, and the server responds with all the data related to that resource, even if the client only needs a subset of it. With GraphQL, clients can specify exactly what data they need and receive it in a single request.

GraphQL has three main components:

1. Schema: The GraphQL schema defines the types of data that can be queried and the relationships between them.
2. Query: The client sends a query to the server, which describes the data it needs.
3. Resolver: The resolver is responsible for fetching the data requested in the query and returning it to the client.

How does GraphQL work?

        GraphQL operates on a simple principle: "Ask for what you need, get exactly that." This means that the client specifies the fields and relationships it needs, and the server returns only that data.

Here's an example of a GraphQL query:

query {
  user(id: 123) {
    firstName
    lastName
    email
    posts {
      title
      body
    }
  }
}

        This query requests the first name, last name, email, and all posts (with their titles and bodies) for a user with an ID of 123.

        When the client sends this query to the server, the server first checks the schema to ensure that the requested fields and relationships are valid. Then, the resolver fetches the data and returns it to the client in a single JSON response.

Benefits of GraphQL

1. Efficient data retrieval: As mentioned earlier, GraphQL enables clients to request only the data they need, and nothing more. This reduces the amount of data transferred over the network and improves performance. With GraphQL, clients can make a single request to retrieve all the data they need, which is especially useful for mobile devices and low-bandwidth connections.
2. Flexible API design: GraphQL enables developers to design flexible APIs that can evolve over time without breaking existing clients. With GraphQL, the server exposes a single endpoint that can handle all types of queries and mutations. This means that developers can add new fields and relationships to the schema without affecting existing clients. Additionally, GraphQL provides a powerful introspection API that allows clients to discover the schema and its capabilities at runtime.
3. Improved developer experience: GraphQL is a developer-friendly API technology that offers a self-documenting nature. The GraphQL schema provides a clear and concise description of the data available in the API, which makes it easier for developers to understand and work with the API. Additionally, GraphQL provides tools for generating client-side code, including type definitions and query builders, which reduces the amount of boilerplate code that developers need to write.
4. Reduced overfetching and underfetching: Overfetching occurs when the server returns more data than the client needs, and underfetching occurs when the server does not return enough data. These problems can arise with REST APIs, where clients are limited to the data structures exposed by the API. With GraphQL, clients can specify exactly what data they need, which reduces overfetching and underfetching.
5. Strong typing: GraphQL has a strong typing system that ensures that the data returned by the server matches the expected types. This reduces the likelihood of runtime errors and makes it easier for developers to reason about their code. Additionally, the strong typing system provides better tooling support, including autocomplete and validation.
6. Ecosystem and community: GraphQL has a growing ecosystem and community, with many tools and libraries available for building GraphQL APIs and clients. The GraphQL community is active and supportive, with many resources available for learning and sharing knowledge.
7. Compatibility with existing data sources: GraphQL can be used with existing data sources, including databases, microservices, and REST APIs. This means that developers can gradually adopt GraphQL without needing to rewrite their entire stack.

Drawbacks of GraphQL

1. Learning curve: GraphQL has a steeper learning curve than REST APIs, especially for developers who are not familiar with the GraphQL syntax and concepts. Additionally, implementing a GraphQL server requires additional infrastructure, such as a GraphQL schema and resolvers.
2. Caching complexity: GraphQL makes it more challenging to implement caching because the data returned by a query depends on the specific fields and relationships requested by the client. This means that caching strategies need to be carefully designed to avoid overcaching or undercaching.
3. Security concerns: Like any API technology, GraphQL can introduce security concerns if not implemented correctly. For example, GraphQL queries can be used to perform denial-of-service attacks, and poorly designed resolvers can expose sensitive data or allow unauthorized access.
4. Potential for performance issues: While GraphQL can improve performance by reducing overfetching and underfetching, poorly designed queries or resolvers can still result in performance issues. Additionally, GraphQL can introduce more network overhead than REST APIs, especially for large or complex queries.

How to use graphql in ruby on rails

1. Add the graphql gem to your Gemfile: In your Rails application's Gemfile, add the graphql gem:

gem 'graphql'

Then run bundle install to install the gem.

2. Generate the GraphQL schema: Run the following command to generate the basic GraphQL schema and related files:

rails generate graphql:install

This will create the app/graphql directory with the app/graphql/types and app/graphql/mutations subdirectories.

3. Define your GraphQL types: In the app/graphql/types directory, create your GraphQL types using the GraphQL::Schema::Object class. For example, you could create a UserType:

module Types
  class UserType < GraphQL::Schema::Object
    field :id, ID, null: false
    field :name, String, null: false
    field :email, String, null: false
  end
end

This defines a UserType with fields for id, name, and email.

4. Define your GraphQL queries: In the app/graphql/types directory, create your GraphQL queries using the GraphQL::Schema::Resolver class. For example, you could create a UsersQuery:

module Types
  class QueryType < GraphQL::Schema::Object
    field :users, [Types::UserType], null: false

    def users
      User.all
    end
  end
end

This defines a users query that returns all users.

5. Define your GraphQL mutations: In the app/graphql/mutations directory, create your GraphQL mutations using the GraphQL::Schema::Mutation class. For example, you could create a CreateUserMutation:

module Mutations
  class CreateUserMutation < GraphQL::Schema::Mutation
    argument :name, String, required: true
    argument :email, String, required: true

    field :user, Types::UserType, null: false

    def resolve(name:, email:)
      user = User.create(name: name, email: email)

      { user: user }
    end
  end
end

This defines a createUser mutation that creates a new user with the specified name and email.

6. Define your GraphQL schema: In the app/graphql directory, create your GraphQL schema using the GraphQL::Schema class. For example:

class MySchema < GraphQL::Schema
  query Types::QueryType
  mutation Types::MutationType
end

This defines a schema with a query field for queries defined in Types::QueryType, and a mutation field for mutations defined in Types::MutationType.

7. Mount your GraphQL endpoint: In your Rails application's routes.rb file, mount your GraphQL endpoint using the mount_graphql_endpoint method. For example:

Rails.application.routes.draw do
  mount_graphql_endpoint '/graphql', schema: MySchema, batch: true
end

        This mounts your GraphQL endpoint at the /graphql path, using the MySchema schema.

        That's it! With these steps, you should be able to get started with using GraphQL in Ruby on Rails. Of course, there are many more advanced topics and techniques you can explore as you become more familiar with GraphQL and Ruby on Rails, but this should give you a good starting point.

Conclusion

        GraphQL is a powerful and flexible API technology that provides many benefits over traditional REST APIs. With its efficient data retrieval, flexible API design, and improved developer experience, GraphQL has become a popular choice for building modern applications. However, GraphQL also has some drawbacks, including a steeper learning curve