如何在MongoDB中通过ID列表查找？
您可以使用$in运算符在MongoDB中查找ID列表。为了理解这个概念，让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.findListOfIdsDemo.insertOne({"StudentName":"Carol","StudentAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ecadd2f684a30fbdfd575")
}
> db.findListOfIdsDemo.insertOne({"StudentName":"Bob","StudentAge":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ecae42f684a30fbdfd576")
}
> db.findListOfIdsDemo.insertOne({"StudentName":"David","StudentAge":22});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ecaed2f684a30fbdfd577")
}
> db.findListOfIdsDemo.insertOne({"StudentName":"John","StudentAge":20});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ecaf82f684a30fbdfd578")
}
> db.findListOfIdsDemo.insertOne({"StudentName":"Mike","StudentAge":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ecb092f684a30fbdfd579")
}在find()method的帮助下显示集合中的所有文档。查询如下-
> db.findListOfIdsDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c8ecadd2f684a30fbdfd575"),
"StudentName" : "Carol",
"StudentAge" : 21
}
{
"_id" : ObjectId("5c8ecae42f684a30fbdfd576"),
"StudentName" : "Bob",
"StudentAge" : 25
}
{
"_id" : ObjectId("5c8ecaed2f684a30fbdfd577"),
"StudentName" : "David",
"StudentAge" : 22
}
{
"_id" : ObjectId("5c8ecaf82f684a30fbdfd578"),
"StudentName" : "John",
"StudentAge" : 20
}
{
"_id" : ObjectId("5c8ecb092f684a30fbdfd579"),
"StudentName" : "Mike",
"StudentAge" : 23
}这是通过ID列表查找的查询-
> var listOfIds = ['5c8ecae42f684a30fbdfd576', '5c8ecaf82f684a30fbdfd578'];
> var documentIds = listOfIds.map(function(myId) { return ObjectId(myId); });
> db.findListOfIdsDemo.find({_id: {$in: documentIds }}).pretty();以下是输出-
{
"_id" : ObjectId("5c8ecae42f684a30fbdfd576"),
"StudentName" : "Bob",
"StudentAge" : 25
}
{
"_id" : ObjectId("5c8ecaf82f684a30fbdfd578"),
"StudentName" : "John",
"StudentAge" : 20
}