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我想在下面的“CarList”数组中插入一个新元素。我在我的项目中使用 MongoDB 和 dropwizzard。

{
    "_id": "56aa6119bf78f37eee64697e",
    "name": "Jack",
    "occupation": "business*emphasized text* owner",
    "carList": [{
        "brand": "Ford",
        "cost": "$25000"
    }, {
        "brand": "Mazda",
        "cost": "$23000 "
    }]
}

我的 POJO 课程：

public class CarOwners {

    @ObjectId
    public String _id;
    public String name;
    public String occupation;
    public List<CarDetails> carList;
}

public class CarDetails
{
    public String brand;
    public String cost;
}

我在 carList 中追加新条目的代码：

CarDetails newCarInfo = new CarDetails();
newCarInfo.brand="Toyota";
newCarInfo.cost="$20000";

BasicDBObject ownerQuery = new BasicDBObject("name", "Jack");
carOwnerCollections.update(ownerQuery, new BasicDBObject("$addToSet", new BasicDBObject("carList",newCarInfo)));

我得到的错误：

org.codehaus.jackson.map.JsonMappingException: Can not instantiate value of type [simple type, class data.CarDetails] from JSON String; no single-String constructor/factory method (through reference chain: data.PropertyLedger["carList"])

从错误中我可以猜测到 CarDetails 类的接线是问题所在。我不知道如何解决它。我查看了更新 Mongo和类似链接中的嵌套文档，但找不到答案。

任何指针都会有所帮助。谢谢你。

4

1 回答 1

0

尝试使用$pushMongoDB 中的数组运算符来执行此操作。

BasicDBObject ownerQuery = new BasicDBObject("name", "Jack");
//Below code will insert the new object to the existing carList array
carOwnerCollections.update(ownerQuery, new BasicDBObject("$push", new BasicDBObject("carList",new BasicDBObject("brand","Toyota").append("cost","$20000"))));
于 2016-06-09T18:02:52.080 回答