MongoDB查询以从JSON之类的数据中查找值？
要通过JSON数据提供值，请使用find()以及dot（。）表示法。首先让我们创建一个包含文档的集合-
> db.findValueFromJsonDemo.insertOne(
{
"UserDetails": [{
"_id": new ObjectId(),
"UserName": "Carol",
"UserMessage": "Hi"
}],
"UserFriendsName": ["John","Sam"]
}
);
{
"acknowledged" : true,
"insertedId" : ObjectId("5cdf8a4cbf3115999ed511fd")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.findValueFromJsonDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cdf8a4cbf3115999ed511fd"),
"UserDetails" : [
{
"_id" : ObjectId("5cdf8a4cbf3115999ed511fc"),
"UserName" : "Carol",
"UserMessage" : "Hi"
}
],
"UserFriendsName" : [
"John",
"Sam"
]
}以下是从json数据中查找值的查询-
> db.findValueFromJsonDemo.find({'UserDetails.UserMessage': "Hi"});这将产生以下输出-
{
"_id" : ObjectId("5cdf8a4cbf3115999ed511fd"),
"UserDetails" : [
{
"_id" : ObjectId("5cdf8a4cbf3115999ed511fc"), "UserName" : "Carol", "UserMessage" : "Hi"
}
],
"UserFriendsName" : [
"John", "Sam"
]
}