How I can find if string exists inside mongodb Array

June 16, 2022

I am trying to find document based on profileID in MongoDB. I want to check if string postid exists in array or not. How I can do that? I tried $all.

Mongo data:

{
  "profileId": "abc",
  "likedPosts": [
    'post1',
    'post2'
  ]
}

Trying to find if post1 exists in array:

findOne({
  profileId
}, {
  likedPosts: {
    $all: ['post1']
  }
}, )

>Solution :

If you want to check if a string exists in an array field you can simply do:

findOne({
  profileId,
  likedPosts: 'post1'
  }
}, )

Docs

Also you might notice i have made the whole query as the first parameter. The second parameter is usually the callback to run, once the query has executed.