Find mongodb doc where an array field has an array item where a sub field exists-CodePudding

Let's say I have schema VideoPosts. VideoPosts has an array field comment.

[
  {
    "user": "1",
    "post": "1",
    "comment": [
      {
        from: "Gene",
        message: "Awesome!"
      },
      {
        from: "Dash",
        message: "Great job!",
        imageAttachment: "www.image.com/imageurl"
      }
    ]
  },
  {
    "user": "1",
    "post": "2",
    "comment": [
      {
        from: "Bill",
        message: "Good video tutorial!"
      }
    ]
  },
  {
    "user": "2",
    "post": "3",
    "comment": [
      {
        from: "Bill",
        message: "This video helped me!"
      }
    ]
  },
  {
    "user": "3",
    "post": "4",
    "comment": [
      {
        from: "Bill",
        message: "I ran into this error:",
        imageAttachment: "www.image.com/imageurl"
      }
    ]
  }
]

I want to find the VideoPost where there is at least one comment with an imageAttachment. In the above example that means post 1 and post 4. I want to use aggregate because I'm going to combine it with some other filters.

I tried this but it did not work

db.collection.aggregate([
  {
    $match: {
      "comments.imageAttachment": {
        "$exists": true
      },
      
    },
    
  },
  
])

playground

CodePudding user response：

it seems just a typo, have you tried same query with comment in singular form?

db.collection.aggregate([
  {
    $match: {
      "comment.imageAttachment": {
        "$exists": true
      },
      
    },
    
  },
  
])