java - 在现有 Mongo 文档中添加更多字段

Question

我正在尝试在现有的 Mongo 文档中添加新字段。

{
    "_id" : ObjectId("51e390ade4b0a29154453698"),
    "group_name" : "om",
    "target_audience" : {
        "gender" : "male",
        "section" : "Item 4",
        "catagory" : "Eletronics",
        "location" : {
            "country" : "Item 3",
            "state" : "Item 3",
            "city" : "Item 4"
        }
    }
}

这是我的文档。我想在此文档中添加更多字段。我编写了以下代码。但不是在同一文档中添加记录，而是替换之前的记录。我的 Java 代码是:

BasicDBObject doc=new BasicDBObject();
        BasicDBObject q=new BasicDBObject("group_name",selectedgn);
        doc.put("date_from",frm);
        doc.put("date_too",too);
        doc.put("description",desc);
        doc.put("url",url);
        BasicDBObject doc1=new BasicDBObject();
        doc1.put("Notification",doc);
        con.coll.update(q,doc1);

Answer 1

正如其他人所说，使用 $set 运算符。您的代码应如下所示(我只更改了最后一行):

BasicDBObject doc=new BasicDBObject();
BasicDBObject q=new BasicDBObject("group_name",selectedgn);
doc.put("date_from",frm);
doc.put("date_too",too);
doc.put("description",desc);
doc.put("url",url);
BasicDBObject doc1=new BasicDBObject();
doc1.put("Notification",doc);
con.coll.update(q,new BasicDBObject("$set",doc1));

或者，如果您只想更新通知子文档中的字段:

BasicDBObject doc=new BasicDBObject();
BasicDBObject q=new BasicDBObject("group_name",selectedgn);
doc.put("Notification.date_from",frm);
doc.put("Notification.date_too",too);
doc.put("Notification.description",desc);
doc.put("Notification.url",url);
con.coll.update(q,new BasicDBObject("$set",doc));