GraphQL APIs with Spring Boot · 课时

GraphQL 变更：修改数据

不要止步于读取数据：学习在 Spring Boot 中定义并实现 GraphQL 变更，以创建、更新和删除数据。

GraphQL 变更：修改数据 是 CoddyKit 上的免费 GraphQL APIs with Spring Boot 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 GraphQL APIs with Spring Boot 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 GraphQL APIs with Spring Boot 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

From Reading to Writing

You can now define types, resolvers, and run queries. But real APIs must also change data.

In GraphQL, every write goes through a mutation — the counterpart to a query.

Query vs Mutation

The shapes look similar, but intent differs:

Query: read data, no side effects, may run in parallel.
Mutation: change data, executed sequentially top to bottom.

Declaring a Mutation in the Schema

Mutations live under the special Mutation type and usually return the affected object.

type Mutation {
  createBook(title: String!, author: String!): Book
}

Input Types for Complex Arguments

For many fields, group arguments into an input type instead of a long argument list.

input BookInput {
  title: String!
  author: String!
}

type Mutation {
  createBook(book: BookInput!): Book
}

Implementing the Resolver

In Spring Boot, annotate the handler with @MutationMapping.

@Controller
class BookMutation {
    @MutationMapping
    Book createBook(@Argument String title, @Argument String author) {
        return new Book(title, author);
    }
}

Returning the Result

Returning the created or updated object lets the client immediately read back any fields it needs.

mutation {
  createBook(title: "Clean Code", author: "Martin") {
    id
    title
  }
}

Update and Delete Mutations

The same pattern covers all writes.

type Mutation {
  updateBook(id: ID!, book: BookInput!): Book
  deleteBook(id: ID!): Boolean
}

A Self-Contained Logic Example

The resolver logic is plain Java; here is the core idea as a runnable snippet.

import java.util.*;
public class Main {
  static Map<Integer,String> store = new HashMap<>();
  static int seq = 0;
  static int createBook(String title){ int id = ++seq; store.put(id, title); return id; }
  public static void main(String[] a){
    int id = createBook("Clean Code");
    System.out.println("Created id=" + id + " title=" + store.get(id));
  }
}

Validating Input

Mutations are the right place to enforce rules: reject empty titles, check permissions, ensure referenced records exist.

Return clear errors so clients can react meaningfully.

Sequential Execution Matters

Unlike query fields, top-level mutation fields run one after another.

This guarantees that if a single request contains several mutations, earlier ones complete before later ones begin — important for consistency.

Best Practices

Use input types for multi-field arguments.
Return the affected object so clients can re-read fields.
Validate and authorize inside resolvers.
Name mutations as verbs: createBook, updateBook, deleteBook.

Quick Check

Test your understanding of GraphQL mutations.

Recap

You learned to change data with GraphQL mutations.

Define them under the Mutation type, often with input types.
Implement with @MutationMapping in Spring Boot.
They run sequentially and should validate and return the affected object.

常见问题解答

「GraphQL 变更：修改数据」课时是免费的吗？

是的 — 「GraphQL 变更：修改数据」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 GraphQL APIs with Spring Boot 课程的其余内容，请升级到 CoddyKit PRO。 GraphQL APIs with Spring Boot 课程共包含 4 节课。

「GraphQL 变更：修改数据」这节课中我会学到什么？

不要止步于读取数据：学习在 Spring Boot 中定义并实现 GraphQL 变更，以创建、更新和删除数据。你通过在浏览器中直接运行的动手代码来练习 GraphQL APIs with Spring Boot，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 GraphQL APIs with Spring Boot 需要有经验吗？

无需任何先前经验。CoddyKit 上的 GraphQL APIs with Spring Boot 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「GraphQL 变更：修改数据」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 GraphQL APIs with Spring Boot 课中编写并运行代码吗？

能。每节 GraphQL APIs with Spring Boot 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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