- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Find items that do not have a certain field in MongoDB?
To find items that do not have a certain field, use the $exists operator. The syntax is as follows −
> db.yourCollectionName.find({"yourItemName":{$exists:false}}).pretty();To understand the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.findDocumentDoNotHaveCertainFields.insertOne({"UserId":101,"UserName":"John","UserAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8a95fb6cea1f28b7aa07fb")
}
> db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"David","UserAge":22,"UserFavouriteSubject":["C","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8a96116cea1f28b7aa07fc")
}
> db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"Bob","UserAge":24,"UserFavouriteSubject":["MongoDB","MySQL"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8a96306cea1f28b7aa07fd")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.findDocumentDoNotHaveCertainFields.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c8a95fb6cea1f28b7aa07fb"),
"UserId" : 101,
"UserName" : "John",
"UserAge" : 21
}
{
"_id" : ObjectId("5c8a96116cea1f28b7aa07fc"),
"UserName" : "David",
"UserAge" : 22,
"UserFavouriteSubject" : [
"C",
"Java"
]
}
{
"_id" : ObjectId("5c8a96306cea1f28b7aa07fd"),
"UserName" : "Bob",
"UserAge" : 24,
"UserFavouriteSubject" : [
"MongoDB",
"MySQL"
]
}Here is the query to find items that do not have certain field i.e. UserFavouriteSubject −
> db.findDocumentDoNotHaveCertainFields.find({"UserFavouriteSubject":{$exists:false}}).pretty();The following is the output −
{
"_id" : ObjectId("5c8a95fb6cea1f28b7aa07fb"),
"UserId" : 101,
"UserName" : "John",
"UserAge" : 21
}
Updated on: 30-Jul-2019
90 Views
Advertisements