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How to count number of keys in a MongoDB document?
There is no in-built function to count a number of keys in a document. In order to count a number of keys, you need to write some code.
Let us create a collection with a document. The query to create a collection with a document is as follows −
> db.numberofKeysInADocumentDemo.insertOne({
"UserName":"John","UserAge":21,"UserEmailId":"john12@gmail.com","UserCountryName":"US"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9132584afe5c1d2279d6ac")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.numberofKeysInADocumentDemo.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c9132584afe5c1d2279d6ac"),
"UserName" : "John",
"UserAge" : 21,
"UserEmailId" : "john12@gmail.com",
"UserCountryName" : "US"
}Here is the query to count the number of keys in a document −
> myDocument = db.numberofKeysInADocumentDemo.findOne({});
{
"_id" : ObjectId("5c9132584afe5c1d2279d6ac"),
"UserName" : "John",
"UserAge" : 21,
"UserEmailId" : "john12@gmail.com",
"UserCountryName" : "US"
}
> numberOfKeys=0;
0
> for(i in myDocument){numberOfKeys ++;}
4
> print("The document has "+ "" +numberOfKeys +" Keys");The following is the output −
The document has 5 Keys
Updated on: 30-Jul-2019
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