MongoDB $type operator

a description

In this section, we will continue our discussion of the conditional operator $type in MongoDB.

The $type operator is based on the BSON type to retrieve the matching data type in the collection and return the result.

The types that can be used in MongoDB are shown in the following table:

Type Number Notes

Double	1
String	2
Object	3
Array	4
Binary data	5
Undefined	6	Obsolete.
Object id	7
Boolean	8
Date	9
Null	10
Regular Expression	11
JavaScript	13
Symbol	14
JavaScript (with scope)	15
32-bit integer	16
Timestamp	17
64-bit integer	18
Min key	255	Query with -1.
Max key	127

 

Two examples

If you want to get the data whose title is String in the "col" collection, you can use the following command:

> use runoob
switched to db runoob
> db.col.find({"title" : {$type : 2}})
{ "_id" : ObjectId("593b87cbbcd6757fd2d30303"), "title" : "PHP 教程", "description" : "PHP 是一种创建动态交互性站点的强 有力的服务器端脚本语言。", "by" : "菜鸟教程", "url" : "http://www.runoob.com", "tags" : [ "php" ], "likes" : 200 }
{ "_id" : ObjectId("593b87dbbcd6757fd2d30304"), "title" : "Java 教程", "description" : "Java 是由Sun Microsystems公司于1995年5月推出的高级程序设计语言。", "by" : "菜鸟教程", "url" : "http://www.runoob.com", "tags" : [ "java" ], "likes" : 150 }
{ "_id" : ObjectId("593b87e5bcd6757fd2d30305"), "title" : "MongoDB 教程", "description" : "MongoDB 是一个 Nosql 数据库", "by" : "菜鸟教程", "url" : "http://www.runoob.com", "tags" : [ "mongodb" ], "likes" : 100 }