GraphQL APIs with Spring Boot · レッスン

DirectiveとContextによる認可

GraphQLのDirectiveとContextを使って認可ルールを適用し、フィールドや操作へのアクセスを制御します。

レッスン 3/412 ステップ

「DirectiveとContextによる認可」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。

What is Authorization?

Welcome! In this lesson, we'll dive into authorization, a critical aspect of API security. Authorization determines what an authenticated user is allowed to do or access.

Authentication: Verifies who you are (e.g., username/password).
Authorization: Verifies what you can do (e.g., access admin data).

Without proper authorization, even authenticated users might access sensitive data or perform actions they shouldn't.

Authorization Challenges in GraphQL

GraphQL's flexible nature presents unique authorization challenges compared to traditional REST APIs:

Field-level access: Clients can request specific fields. You might need to restrict access to individual fields within a type.
Nested data: Complex queries can fetch deeply nested data. Authorization checks need to apply throughout the query tree.
Dynamic roles: User roles and permissions can vary, requiring dynamic checks.

We need robust mechanisms to enforce these rules effectively.

Introducing GraphQL Directives

GraphQL directives are powerful features that allow you to extend the schema with custom logic. They are denoted by an @ symbol, like @deprecated or @skip.

Think of them as annotations for your schema. They can be attached to fields, types, arguments, and more, allowing you to add metadata or alter the execution behavior of your GraphQL API.

Custom Directive: @hasRole

We can define our own custom directives for authorization. A common example is an @hasRole directive. This directive would allow you to specify required roles directly in your schema.

Here's how you might define it in your Schema Definition Language (SDL):

directive @hasRole(role: String!) on FIELD_DEFINITION

This declares a directive named hasRole that takes a mandatory role argument (a String) and can only be applied to a FIELD_DEFINITION.

Spring Boot Directive Wiring

To make a custom directive functional in Spring Boot, you need to 'wire' it. This involves implementing the SchemaDirectiveWiring interface from graphql-java.

This wiring class intercepts the schema parsing process and allows you to modify how fields or types behave when your directive is encountered. It's where you'll inject your authorization logic.

Implementing Directive Logic

Inside your SchemaDirectiveWiring implementation, you'll override methods like onField. When the GraphQL engine processes a field with your @hasRole directive, this method is called.

Within onField, you can:

Extract the required role from the directive's arguments.
Get the current user's roles from the GraphQL Context.
Compare the roles and, if unauthorized, throw an exception or return null.

GraphQL Context for User Info

The GraphQL Context is a crucial object that accompanies every GraphQL request. It's like a backpack for your request, carrying request-scoped data that resolvers and directive wirings can access.

For authorization, the context is where you'll typically store information about the currently authenticated user, such as their ID, username, and crucially, their roles or permissions.

Integrating User Context (Runnable)

Here's a minimal Spring Boot app demonstrating how to inject user roles into the GraphQLContext. This context can then be accessed by your resolvers and directive wirings.

Try running this and querying myRoles to see the injected roles.

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import graphql.kickstart.tools.GraphQLQueryResolver;
import graphql.schema.GraphQLContext;
import graphql.kickstart.servlet.context.GraphQLServletContextBuilder;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.websocket.Session;
import javax.websocket.server.HandshakeRequest;
import java.util.Arrays;
import java.util.List;
import java.util.HashMap;
import java.util.Map;

@SpringBootApplication
public class ContextDemoApp {

    public static void main(String[] args) {
        SpringApplication.run(ContextDemoApp.class, args);
    }

    // Resolver to show context access
    @Bean
    public GraphQLQueryResolver queryResolver() {
        return new GraphQLQueryResolver() {
            public List<String> myRoles(GraphQLContext context) {
                Map<String, Object> user = context.get("user");
                if (user != null && user.containsKey("roles")) {
                    return (List<String>) user.get("roles");
                } 
                return Arrays.asList("GUEST");
            }
        };
    }

    // Custom GraphQLContextBuilder to inject user data
    @Bean
    public GraphQLServletContextBuilder graphQLServletContextBuilder() {
        return new GraphQLServletContextBuilder() {
            @Override
            public GraphQLContext build(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
                Map<String, Object> user = new HashMap<>();
                user.put("id", "user123");
                user.put("name", "Coddy");
                user.put("roles", Arrays.asList("USER", "EDITOR")); // Mock roles
                GraphQLContext context = GraphQLContext.newContext().build();
                context.put("user", user); // Add user to context
                return context;
            }

            @Override
            public GraphQLContext build(Session session, HandshakeRequest handshakeRequest) {
                // Not used in typical HTTP requests, but required for interface
                return GraphQLContext.newContext().build();
            }
        };
    }
}

Applying Directives in Schema

Once your @hasRole directive is defined and wired up, you can apply it directly to your schema fields. This makes authorization rules declarative and easy to see.

For example, to restrict a field called adminDashboard to users with the ADMIN role:

type Query {
  myRoles: [String]
  adminDashboard: String @hasRole(role: "ADMIN")
}

Now, any attempt to query adminDashboard will trigger your directive's logic, which checks the user's roles from the context.

Authorization Flow: Directive + Context

Let's put it all together. When a client queries a field like adminDashboard:

The Spring Boot GraphQL runtime receives the request.
The GraphQLContextBuilder populates the GraphQLContext with the authenticated user's details, including roles (as shown in the runnable example).
The @hasRole directive wiring intercepts the adminDashboard field.
Inside the directive's logic, it retrieves the required role ("ADMIN") from the directive arguments and the user's roles from the GraphQLContext.
If the user has the required role, the query proceeds to the field's data resolver. Otherwise, an authorization error is returned.

Check Your Understanding

Which of the following best describes the primary purpose of the GraphQL Context in the context of authorization?

対話的なレッスンで答える

Recap: Directives & Context

You've learned how to implement robust authorization in GraphQL with Spring Boot!

Authorization controls what an authenticated user can access.
GraphQL Directives extend schema behavior, allowing declarative authorization rules like @hasRole.
The GraphQL Context is essential for carrying dynamic, request-scoped user information (like roles) to enable these authorization checks.

By combining directives and context, you can build secure and flexible GraphQL APIs.

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よくある質問

「DirectiveとContextによる認可」レッスンは無料ですか？

はい。「DirectiveとContextによる認可」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。

「DirectiveとContextによる認可」で何を学びますか？

GraphQLのDirectiveとContextを使って認可ルールを適用し、フィールドや操作へのアクセスを制御します。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。

「DirectiveとContextによる認可」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。

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