使用MongoDB从数组中的对象的一部分查询
要查询数组中对象的一部分，请使用$findOne()和$all。首先让我们创建一个包含文档的集合-
> db.demo25.insertOne(
... {
...
... "Details":[
... {
... "UserId":"Carol101",
... "UserName":"Carol"
... },
... {
... "UserId":"David102",
... "UserName":"David"
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e14c86e22d07d3b95082e77")
}
> db.demo25.insertOne(
... {
...
... "Details":[
... {
... "UserId":"Chris101",
... "UserName":"Chris"
... },
... {
... "UserId":"Mike102",
... "UserName":"Mike"
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e14c86f22d07d3b95082e78")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo25.find();
这将产生以下输出-
{ "_id" : ObjectId("5e14c86e22d07d3b95082e77"), "Details" : [ { "UserId" : "Carol101", "UserName" : "Carol" }, { "UserId" : "David102", "UserName" : "David" } ] }
{ "_id" : ObjectId("5e14c86f22d07d3b95082e78"), "Details" : [ { "UserId" : "Chris101", "UserName" : "Chris" }, { "UserId" : "Mike102", "UserName" : "Mike" } ] }这是如何从数组中对象的一部分进行查询-
> db.demo25.findOne({ "Details.UserId":{$all : ["Carol101","David102"]}});这将产生以下输出-
{
"_id" : ObjectId("5e14c86e22d07d3b95082e77"),
"Details" : [
{
"UserId" : "Carol101",
"UserName" : "Carol"
},
{
"UserId" : "David102",
"UserName" : "David"
}
]
}