java - 如何编写更新嵌入文档的查询

Question

我是 spring data mongodb 的新手，但我只是坚持如何使用 mongo 存储库为嵌入式文档编写基于 json 的查询。

我的数据库看起来像

"_id" : ObjectId("5565ad670cf25cbd975ab2d9"),
    "_class" : "com.samepinch.domain.metadata.Metadata",
    "preferenceType" : "shopping",
    "subtypes" : [
        {
            "_id" : ObjectId("5565ad670cf25cbd975ab2d2"),
            "subType" : "veg",
            "preferencePoint" : 0
        },
        {
            "_id" : null,
            "subType" : "nonveg",
            "preferencePoint" : 0
        }
    ],
    "createdDate" : ISODate("2015-05-27T11:41:27.357Z"),
    "updatedDate" : ISODate("2015-05-27T11:41:27.357Z")

我想根据顶级文档 ID 更新子类型，我必须更新 ID 为 5565ad670cf25cbd975ab2d2 的子类型的首选项点 ，如何为此编写查询？

Answer 1

您应该使用$ projection使用 $elemMatch 查询如下:

db.collectionName.update({"_id" : ObjectId("5565ad670cf25cbd975ab2d9"),
"subtypes":{"$elemMatch":{"_id":ObjectId("5565ad670cf25cbd975ab2d2")}}},
{"$set":{"subtypes.$.preferencePoint":1}})

其等效的 java 代码为:

BasicDBObject eleMatch = new BasicDBObject();
eleMatch.put("_id", new ObjectId("5565ad670cf25cbd975ab2d2"));
BasicDBObject elemMatchQuery = new BasicDBObject();
elemMatchQuery.put("$elemMatch", eleMatch);
BasicDBObject query = new BasicDBObject();
query.put("_id", new ObjectId("5565ad670cf25cbd975ab2d9"));
query.put("subtypes", elemMatchQuery);
BasicDBObject set = new BasicDBObject();
set.put("subtypes.$.preferencePoint", 1);
BasicDBObject update = new BasicDBObject();
update.put("$set", set);
DBCollection dbcoll = mongoTemplate.getCollection("collectionName");
DBObject object = dbcoll.update(query, update);