intro-to-graphql

Intro to graphQL

This is a demo project for getting started with graphql. In this project there is create, read and delete operations. Implementing the update operation is left for your self practice.

This Project also includes the tests that covers 100% of the codebase.

We didn’t use an actual database though, we have used a fake in memory database(Simple data structures in this case - List<Author> authors for Authors and List<Book> books for Books).

This database will be empty when the application starts, and also will be removed if the application is stopped. So, restarting your application would get you a new fresh empty database everytime.

This project has four packages:.

1. controller package

In this package, there are two controllers, there are two types of mapping in this project: @QueryMapping and @MutationMapping. @QueryMapping can be compared with the GET request, though all the requests of graphql is POST request, and @MutationMapping can be compared with the POST request. Controller classes should be annotated with @Controller.

AuthorController.java controls the Author related request-response and the BookController.java controls the Book related request-response.

2. model package

In this package, there are two types of data model, one is Author and another is Book. These models hold the data of the Book and the Author.

3. repository package

In this package, there are two repository, one is AuthorRepository and another is BookRepository. The holds the information about the database and the methods to operate on the database. Repositories should be annotated with @Repository.

4. service package

In this package, there are two Interface named AuthorService and BookService. They both hold the functionality of what a user can do with these. We define the business logic, or the service we want to get with this model and controller. Services should be annotated with @Service.

Sending request

We can use postman or the graphiql interface. Graphiql interface is a default graphical user interface to work with graphql request and response. To enable the graphiql interface for a graphql project, we need to enable it from the application.properties file of our project. To enable it, we need to add spring.graphql.graphiql.enabled=true in our application.properties file.

After running the application, the graphiql can be accessed via http://localhost:8080/graphiql url.

These are the queries this project supports for Authors.

Sample query for adding author:

mutation{
  addAuthor(firstName: "Kazi", lastName: "Afsana")
}

Sample query for removing author by name:

mutation{
    removeAuthor(firstName: "kazi", lastName: "Afsana")
}

Sample query for getting author by name:

{
  author(firstName: "Kazi", lastName: "Afsana"){
    id
    firstName
    lastName
  }
}

Sample query for all authors:

{
  authors{
    id
    firstName
    lastName
  }
}

These are the queries this project supports for Books.

Sample query for adding book

mutation {
  addBook(name: "101 ways to bake", pageCount: 290, authorFirstName: "Kazi")
}

Sample query for removing a book

mutation {
    removeBook(name: "101 ways to bake")
}

Sample query for getting a book

{
    book(name: "101 ways to bake"){
        id
        name
        pageCount
        author{
            id
            firstName
            lastName
        }
    }
}

Sample query for getting all books

{
   books{
  	  id
  	  name
  	  pageCount
  	  author{
  	      id
  	      firstName
  	      lastName
      }
   } 
}

Feel free to suggest any changes. Happy coding! ❤

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