Replace value in array

Question

I am using Mongodb C# official driver. I want to change a particular value in an array with some other value. The array contains list of values. For eg.

{ 
   _id: id1,
   values: [23, 78, 20]
}

I want suppose to replace 23 by 25. I know one answer if it is right. First I pull that element and then push other. But the problem is that if the element is not present then also push will insert the element. Secondly, it will change the position and insert the element at the end. Please tell me how to do it.

I have read but all examples are about incrementing the value. — Himani Talesara
– Himani Talesara, Commented May 11, 2012 at 19:51
I just did it and it worked as expected. There's problem in your code. — Sergio Tulentsev
– Sergio Tulentsev, Commented May 11, 2012 at 20:02

Sergio Tulentsev · Accepted Answer · 2012-05-12 04:48:36Z

6

You should use this:

db.collection.update({_id: id1, values: 23}, {$set: {'values.$': 25}})

edited May 12, 2012 at 4:48

answered May 11, 2012 at 20:18

Sergio Tulentsev

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5 Comments

Gates VP Over a year ago

I think you need to add the _id to this answer. Otherwise you will update the first document with a value of 23, which is not what you want.

Himani Talesara Over a year ago

@GatesVP: Thanks it works. But what to do if I want each occurence of 23 to be replaced by certain number. $ works for first matched.

Sergio Tulentsev Over a year ago

@HimaniTalesara: you can run this update repeatedly, or you can fetch the document to the app, modify it there and save back.

Gates VP Over a year ago

db.collection.update({values:23}, {$set: {'values.$': 25}}, false, true) That extra false is "do not upsert". That extra true is "perform this update multiple times".

Sergio Tulentsev Over a year ago

@GatesVP: that won't work if he needs to replace multiple values in the same document. :)

Community · Accepted Answer · 2017-05-23 12:32:49Z

2

This should work with you

db.collection.update({ "_id" : id1 }, {$set: {"values.0": 23}});

check this post as well Update mongo array elements by index with c-driver

edited May 23, 2017 at 12:32

CommunityBot

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answered May 11, 2012 at 20:24

DIna AK

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