データの更新と削除
既存のデータを変更したり、システムからレコードを削除したりするMutationを開発します。
「データの更新と削除」はCoddyKit上の無料GraphQL APIs with Spring Bootレッスンです。 これはレッスン3/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはGraphQL APIs with Spring Boot学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 GraphQL APIs with Spring Bootコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
Changing Your Data
So far, you've learned to fetch data with queries and add new data with mutations. But what about modifying or removing existing records?
In this lesson, we'll dive into how GraphQL mutations allow you to update and delete data, making your applications fully dynamic.
GraphQL Update Mutation (SDL)
An update mutation modifies an existing record. It usually requires an identifier (like an ID) to specify which record to change, and then the fields you want to update.
Here's how you might define an updateBook mutation in your GraphQL schema (SDL):
type Mutation {
updateBook(id: ID!, title: String, author: String, year: Int): Book
}
Designing Update Input Types
For cleaner mutations, especially with many fields, it's good practice to use an Input Type. This bundles all arguments into a single object.
An Input Type is similar to a regular type but uses the input keyword.
input UpdateBookInput {
id: ID!
title: String
author: String
year: Int
}
type Mutation {
updateBook(input: UpdateBookInput!): Book
}
Spring Boot: Update Resolver
In your Spring Boot application, you'll create a Java method that acts as the resolver for the updateBook mutation.
This method will take the necessary arguments (like the book's ID and new details) and perform the update logic, often interacting with a database or service.
public Book updateBook(String id, String title, String author, Integer year) {
// ... logic to find and update the book ...
return updatedBook;
}
Implementing Update Logic
Let's see a simple Java example of how an update might work. We'll use an in-memory list to simulate a data store.
Notice how we find the book by ID and then modify its properties.
public class Main {
static class Book {
String id;
String title;
public Book(String id, String title) {
this.id = id;
this.title = title;
}
public String getId() { return id; }
public String getTitle() { return title; }
public void setTitle(String title) { this.title = title; }
@Override
public String toString() { return "Book[id=" + id + ", title='" + title + "']"; }
}
private static java.util.List<Book> books = new java.util.ArrayList<>();
public static void main(String[] args) {
books.add(new Book("1", "Original Title"));
books.add(new Book("2", "Another Book"));
System.out.println("Before update:");
books.forEach(System.out::println);
// Simulate update logic
String targetId = "1";
String newTitle = "Updated Title";
books.stream()
.filter(b -> b.getId().equals(targetId))
.findFirst()
.ifPresent(book -> book.setTitle(newTitle));
System.out.println("\nAfter update:");
books.forEach(System.out::println);
}
}GraphQL Delete Mutation (SDL)
Deleting data is simpler. You typically only need to provide the unique ID of the record you wish to remove.
The delete mutation usually returns the ID of the deleted item, or a boolean indicating success.
type Mutation {
deleteBook(id: ID!): ID
}
Spring Boot: Delete Resolver
Similar to updating, a delete mutation in Spring Boot will have a corresponding Java method.
This method will receive the ID of the item to be deleted and perform the removal operation.
public String deleteBook(String id) {
// ... logic to find and delete the book ...
return id;
}
Implementing Delete Logic
Here's a basic Java example of a delete operation. We'll remove a book from our in-memory list based on its ID.
The removeIf method is a concise way to delete elements that match a condition.
public class Main {
static class Book {
String id;
String title;
public Book(String id, String title) {
this.id = id;
this.title = title;
}
public String getId() { return id; }
public String getTitle() { return title; }
@Override
public String toString() { return "Book[id=" + id + ", title='" + title + "']"; }
}
private static java.util.List<Book> books = new java.util.ArrayList<>();
public static void main(String[] args) {
books.add(new Book("1", "Book to Delete"));
books.add(new Book("2", "Another Book"));
System.out.println("Before delete:");
books.forEach(System.out::println);
// Simulate delete logic
String targetId = "1";
books.removeIf(book -> book.getId().equals(targetId));
System.out.println("\nAfter delete:");
books.forEach(System.out::println);
}
}Handling Missing Records
What happens if you try to update or delete a record that doesn't exist?
- Your resolver should check if the
IDexists. - If not found, it can return
nullor throw a specific GraphQL error (more on error handling in a later course!). - This prevents unexpected behavior and informs the client.
Quick Check: Mutation Operations
You've learned about different types of GraphQL operations. Let's test your understanding!
Recap: Mastered Data Changes!
Congratulations! You've learned how to implement powerful data modification features:
- Update Mutations: Used to modify existing data records, identified by a unique ID.
- Delete Mutations: Used to remove data records from your system, also identified by a unique ID.
- Spring Boot Resolvers: How to map these mutations to Java methods for backend logic.
With queries, create, update, and delete mutations, you now have a full set of tools to build dynamic GraphQL APIs!
よくある質問
「データの更新と削除」レッスンは無料ですか？
はい。「データの更新と削除」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、GraphQL APIs with Spring Bootコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 GraphQL APIs with Spring Bootコースには全4レッスンが含まれています。
「データの更新と削除」で何を学びますか？
既存のデータを変更したり、システムからレコードを削除したりするMutationを開発します。 ブラウザで直接実行するハンズオンコードでGraphQL APIs with Spring Bootを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
GraphQL APIs with Spring Bootを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのGraphQL APIs with Spring Bootは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン3/4です。
「データの更新と削除」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このGraphQL APIs with Spring Bootレッスンでコードを書いて実行できますか？
はい。すべてのGraphQL APIs with Spring Bootレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。