Are mongodb ids unique ?

MongoDB ifNull Array - Aggregation

$ifNull  (aggregation)

$ifNull is used to evaluate an expression and returns value. If the expression evaluates to a null value that time it returns to replacement expression value.

Syntax: 

{ $ifNull: [ “expression”, “replacement-expression-if-value-is-null”] }

For example,

db.customers.aggregate([{
       $project: {CustID: 1001,
       CustomerCode: { $ifNull: [ "$CustomerCode ", "Pending Approval" ] } }
 } ]);

In the above example, if customer code is null that time the expression returns to “Pending Approval” (as per you).

Thank you!



ANIL SINGH

Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..

My Tech Blog - https://www.code-sample.com/
My Books - Book 1 and Book 2

www.code-sample.com/. Powered by Blogger.
^