使用Jongo和MongoDB在Jackson反序列化中将ObjectId _id重命名为id [英] Rename ObjectId _id to id in jackson deserialization with Jongo and MongoDB

问题描述

我刚刚开始使用play框架，jongo和MongoDB开发项目。该项目最初是在Play 2.1中用pojos编写的，其字符串ID字段用以下两个注释：@Id和@ObjectId这将作为ObjectId持久保存到Mongo，并且当反序列化时将id输出为：id：53fcb9ede4b0b18314098d10例如。

I've just started working on a project using the play framework,jongo and MongoDB. The project was initially written in Play 2.1 with pojos with an String id field annotated with both: @Id and @ObjectId This would persist to Mongo as an ObjectId and when deserialized would output the id as: "id":"53fcb9ede4b0b18314098d10" for example.

自从升级到Jongo 1.1和Play 2.3.3后，id属性在反序列化时始终被命名为_id，我希望该属性保留字段名称但我可以'使用@JsonProperty（custom_name）作为Jongo @Id注释在幕后执行@JsonProperty（_ id）。

Since upgrading to Jongo 1.1 and Play 2.3.3 the id attribute is always named "_id" when deserialized, I want the attribute to retain the field name yet I can't use @JsonProperty("custom_name") as the Jongo @Id annotation does @JsonProperty("_id") behind the scenes.

import org.jongo.marshall.jackson.oid.Id;
import org.jongo.marshall.jackson.oid.ObjectId;

public class PretendPojo {

    @Id
    @ObjectId
    private String id;

    private String name;

    public PretendPojo() {
    }

    public PretendPojo(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

在MongoDB中保留的POJO如果我是这样的话通过RoboMongo查看它们

The POJOs when persisted in MongoDB look like this if I view them via RoboMongo

{
    "_id" : ObjectId("53fc984de4b0c34f1905b8ee"),
    "name" : "Owen"
}

但是当我反序列化时如果我保留两个注释，我会得到以下json：

However when I deserialize them I get the following json if I keep both annotations:

{"name":"Owen","_id":{"time":1409072858000,"date":1409072858000,"timestamp":1409072858,"new":false,"timeSecond":1409072858,"inc":308487737,"machine":-458223042}}

以及以下输出，如果我只使用@Id注释。

and the following output if I only use the @Id annotation.

{"name":"Owen","_id":"53fcbedae4b0123e12632639"}

我有一个测试用例，用于处理上面的PretendPojo节目：

I have a test case for working with the PretendPojo show above:

   @Test
    public void testJongoIdDeserialization() throws UnknownHostException {
        DB database = new MongoClient("localhost", 27017).getDB("jongo");
        Jongo jongo = new Jongo(database);
        MongoCollection collection = jongo.getCollection("jongo");
        collection.save(new PretendPojo("Owen"));
        PretendPojo pretendPojo = collection.findOne("{name:   \"Owen\"}").as(PretendPojo.class);
        JsonNode json = Json.toJson(pretendPojo);
        assertNotNull(json.get("id"));
    }

当尝试使用自定义反序列化器时，我永远无法获得对象ID I似乎只能访问当前正在反序列化的日期/时间/时间戳数据。

When trying to use custom deserializers I never can get hold of the object ID I seem to only have access to the date/time/timestamp data that is currently being deserialized.

理想情况下，我正在寻找的输出是：

Ideally the output I'm looking for would be:

  {"name":"Owen","id":"53fcbedae4b0123e12632639"}

任何帮助将不胜感激！ ：）

Any help will be greatly appreciated! :)

推荐答案

ObjectIdSerializer 总是将使用@ObjectId映射的属性写入ObjectId的新实例。将此属性映射到String时出错。

ObjectIdSerializer always writes property mapped with @ObjectId to a new instance of ObjectId. This is wrong when you map this property to a String.

为了避免这种情况，我编写了NoObjectIdSerializer：

To avoid this behaviour, I've write a NoObjectIdSerializer :

public class NoObjectIdSerializer extends JsonSerializer<String> {
    @Override
    public void serialize(String value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
        jgen.writeString(value);
    }
}

使用如下：

@ObjectId
@JsonSerialize(using = NoObjectIdSerializer.class)
protected final String _id;

一个未解决的问题。

这篇关于使用Jongo和MongoDB在Jackson反序列化中将ObjectId _id重命名为id的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！