Mongodb - use $type to query whether the type of a field is XXX

A friend asked me why I have been updating recently mongodb Related operation tutorials ？ Because , I need it in my current job .

My current main work will involve data validation after data cleaning , Generally, it is warehoused to mongodb In the library , To master skillfully mongodb Some usage words of , It can help you quickly find out whether there is abnormal data , Check the quality of data from all aspects .

such as ： The product documentation states that a field should be of numeric type , Then you can write a query statement to reverse query whether there is data that does not meet the requirements .

Next , Learning today mongodb in $type Usage of ：

Inquire about user In the table age Field is string Data of type ：

db.getCollection("user").find({age:{$type:"string"}})
db.getCollection("user").find({age:{$type:2}})

mongo The common types in and the mapping table corresponding to the number relationship that can be used in query statements are as follows ：

The above is just some common enumeration values enumerated by others , It may be updated later , In use , If you enter the wrong type to query , The query will report an error . At present, I only come into contact with numbers in my work 、 character string 、ObjectId、 Array 、Null type , I don't know what other types are at present , You can make a detailed introduction after you get in touch with it in the future .

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