如何在MongoDB中连接结果？
您可以在的帮助下合并结果forEach()。首先让我们创建一个包含文档的集合-
> db.concatenateDemo.insertOne({"Name":"John","Age":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc80dd88f9e6ff3eb0ce448")
}
> db.concatenateDemo.insertOne({"Name":"Carol","Age":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc80de18f9e6ff3eb0ce449")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.concatenateDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cc80dd88f9e6ff3eb0ce448"),
"Name" : "John",
"Age" : 21
}
{
"_id" : ObjectId("5cc80de18f9e6ff3eb0ce449"),
"Name" : "Carol",
"Age" : 23
}这是连接结果的查询-
> db.concatenateDemo.find().forEach( function (result) {result.NameAndAge = result.Name + ' ' + result.Age; printjson(result); } );这将产生以下输出-
{
"_id" : ObjectId("5cc80dd88f9e6ff3eb0ce448"),
"Name" : "John",
"Age" : 21,
"NameAndAge" : "John 21"
}
{
"_id" : ObjectId("5cc80de18f9e6ff3eb0ce449"),
"Name" : "Carol",
"Age" : 23,
"NameAndAge" : "Carol 23"
}