如何动态忽略 Jackson 序列化的属性

问题描述

我有一个具有多个 @ManyToOne 关联的实体.我正在使用 spring-boot 来公开一个 REST API.目前，我有多个 REST API，它们返回整个实体的 JSON 响应，包括关联.

I have an entity with multiple @ManyToOne associations. I am using spring-boot to expose a REST API. Currently, I have multiple REST API's which return a JSON response of the whole entity, including associations.

但我不想序列化所有 REST API 中的所有关联对象.

But I don't want to serialize all associated objects in all REST APIs.

例如

• API-1 应该返回 parent + associationA 对象
• API-2 应该返回 parent + associationA + associationB 对象
• API-3 应该返回父级 + 关联 B + 关联 C + 关联 D

所以，在我的序列化过程中，我想忽略除 API-1 的 AssociationA 之外的所有关联.

So, in my serialization process, I want to ignore all association except associationA for API-1.

对于 API-2，我想忽略除 A 和 B 之外的其他关联

For API-2 I want to ignore other associations except A and B

如何在 Jackson 序列化期间动态忽略这些属性?

How do I dynamically ignore these properties during Jackson serialization?

注意事项:我为每个使用相同的类；我对为每个 API 创建 DTO 不感兴趣.

Notes:I'm using the same class for each; I am not interested in creating a DTO for each API.

非常感谢任何建议.

推荐答案

我已经将三种在 Jackson 中执行动态过滤的方法放在一起.其中之一必须满足您的需求.

I've put together three approaches for performing dynamic filtering in Jackson. One of them must suit your needs.

你可以使用 @JsonView:

You could use @JsonView:

public class Views {
    interface Simple { }
    interface Detailed extends Simple { }
}

public class Foo {

    @JsonView(Views.Simple.class)
    private String name;

    @JsonView(Views.Detailed.class)
    private String details;

    // Getters and setters
}

@RequestMapping("/foo")
@JsonView(Views.Detailed.class)
public Foo getFoo() {
    Foo foo = new Foo();
    return foo;
}

或者，您可以使用 MappingJacksonValue.

Alternatively you can set the view dynamically with MappingJacksonValue.

@RequestMapping("/foo")
public MappingJacksonValue getFoo() {
    Foo foo = new Foo();
    MappingJacksonValue result = new MappingJacksonValue(foo);
    result.setSerializationView(Views.Detailed.class);
    return result;
}

使用 BeanSerializerModifier

您可以扩展BeanSerializerModifier 然后覆盖 changeProperties() 方法.它允许您根据需要添加、删除或替换任何用于序列化的属性:

Using a BeanSerializerModifier

You could extend BeanSerializerModifier and then override the changeProperties() method. It allows you to add, remove or replace any of properties for serialization, according to your needs:

public class CustomSerializerModifier extends BeanSerializerModifier {

    @Override
    public List<BeanPropertyWriter> changeProperties(SerializationConfig config,
        BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {

        // In this method you can add, remove or replace any of passed properties

        return beanProperties;
    }
}

然后将序列化程序注册为ObjectMapper:

Then register the serializer as a module in your ObjectMapper:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new SimpleModule() {

    @Override
    public void setupModule(SetupContext context) {
        super.setupModule(context);
        context.addBeanSerializerModifier(new CustomSerializerModifier());
    }
});

检查示例此处和这里.

另一种方法涉及@JsonFilter:

Another approach involves @JsonFilter:

@JsonFilter("customPropertyFilter")
public class Foo {

    private String name;
    private String details;

    // Getters and setters
}

扩展 SimpleBeanPropertyFilter 并覆盖 serializeAsField() 方法根据您的需要:

Extend SimpleBeanPropertyFilter and override the serializeAsField() method according to your needs:

public class CustomPropertyFilter extends SimpleBeanPropertyFilter {

    @Override
    public void serializeAsField(Object pojo, JsonGenerator jgen,
                                 SerializerProvider provider,
                                 PropertyWriter writer) throws Exception {

        // Serialize a field
        // writer.serializeAsField(pojo, jgen, provider, writer);

        // Omit a field from serialization
        // writer.serializeAsOmittedField(pojo, jgen, provider);
    }
}

然后在您的中注册过滤器ObjectMapper:

FilterProvider filterProvider = new SimpleFilterProvider()
        .addFilter("customPropertyFilter", new CustomPropertyFilter());

ObjectMapper mapper = new ObjectMapper();
mapper.setFilterProvider(filterProvider);

如果你想让你的过滤器全局"，即应用到所有的beans，你可以创建一个mix-in类并用@JsonFilter("customPropertyFilter"):

If you want to make your filter "global", that is, to be applied to all beans, you can create a mix-in class and annotate it with @JsonFilter("customPropertyFilter"):

@JsonFilter("customPropertyFilter")
public class CustomPropertyFilterMixIn {

}

然后将mix-in类绑定到Object:

Then bind the mix-in class to Object:

mapper.addMixIn(Object.class, CustomPropertyFilterMixIn.class);

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