- 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
How to get the index of an array element in older versions on MongoDB?
To get index of an array element, use $indexOfArray. Let us create a collection with documents −
> db.demo65.insertOne({"ListOfValues":[10,20,30]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e28990ecfb11e5c34d89938")
}
> db.demo65.insertOne({"ListOfValues":[50,60,70,100]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e28991ecfb11e5c34d89939")
}
> db.demo65.insertOne({"ListOfValues":[30,40,89,91,98]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e28992bcfb11e5c34d8993a")
}
Display all documents from a collection with the help of find() method −
> db.demo65.find();
This will produce the following output −
{ "_id" : ObjectId("5e28990ecfb11e5c34d89938"), "ListOfValues" : [ 10, 20, 30 ] }
{ "_id" : ObjectId("5e28991ecfb11e5c34d89939"), "ListOfValues" : [ 50, 60, 70, 100 ] }
{ "_id" : ObjectId("5e28992bcfb11e5c34d8993a"), "ListOfValues" : [ 30, 40, 89, 91, 98 ] }
Here is the query to get the index of an array element in older versions on MongoDB −
> db.demo65.aggregate(
... [
... {
... $project:
... {
... IndexOfAnArrayElement: { $indexOfArray: [ "$ListOfValues", 30] },
... }
... }
... ]
... );
This will produce the following output −
{ "_id" : ObjectId("5e28990ecfb11e5c34d89938"), "IndexOfAnArrayElement" : 2 }
{ "_id" : ObjectId("5e28991ecfb11e5c34d89939"), "IndexOfAnArrayElement" : -1 }
{ "_id" : ObjectId("5e28992bcfb11e5c34d8993a"), "IndexOfAnArrayElement" : 0 }
Updated on: 2020-03-30T07:23:50+05:30
175 Views
Advertisements