[英]How to aggregate over map keys across all the documents in mongodB collection?
[英]how to keep special keys in filed of mongoDB documents and remove extra keys in there?
假設我有 mongoDB 集合,其中包含如下文件
{
"_id" : ObjectId("5cb2dd4d378a8e2484e7bb69"),
"name":"ali",
"creator" : {
"name":"user1",
"code":2,
"type" : "desk",
"type_id" : "desk::bb36640a-e384-45ec-aafa-ce71b724c389"
},
"creatorPosition" : {
"name":"user2",
"role":"admin",
"type" : "position",
"type_id" : "position::9f711bb3-3aad-4936-b75a-4ddd024b4bb1"
},
"creatorDetails" : {
"name":"user1",
"type" : "deskUserAssignment",
"type_id" : "deskUserAssignment::dd46fa14-0fd3-43d7-8312-471bc253ee80"
}
}
我想從每個字段中保留兩個鍵值( "type", "type_id"
)並刪除額外的鍵(例如"name", "code", "role"
)
我可以在一個 mongo 查詢中處理這個問題嗎?
另外,我想在java中寫這段代碼
最簡單的方法是使用MongoTemplate提供的 Projection
例如,包括使用org.springframework.data.mongodb.core.query.Query
和org.springframework.data.mongodb.core.MongoTemplate
檢索結果的字段:
Query query = new Query(); query.fields().include("creator.type").include("creator.type_id"); query.fields().include("creatorPosition.type").include("creatorPosition.type_id"); query.fields().include("creatorDetails.type").include("creatorDetails.type_id"); List<Document> documents = mongoTemplate.find(query, Document.class, "your_collection");
有關更多信息,請參閱本文: https://www.mkyong.com/mongodb/spring-data-mongodb-select-fields-to-return/
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