Update if object prop doesn't exist in array

Question

I'd like to $push the variable content into the database content if the content.hash isn't already in the database. I don't want to store information again unnecessarily.

return shops.updateAsync({
  "user": user
}, {
  "$push": {
    "content": content
  }
})

I have a content object with the following params.

content = {
  "type": "csv",
  "name: "my-csv.csv",
  "content": csvContent,
  "date": new Date(),
  "hash": hash.digest('hex')
}

I don't want to ever insert the same CSV into the array. I'd like to ensure that there's only one by checking the hash, if there's a content object in the array with the hash it wouldn't upload or overwrite it.

Here's what I got so far, it's 3 requests :(

return users.findOneAsync({
  "user": user,
  "content.hash": content.hash,
}).then(function(exists){
  if(!exists) return false
  return users.updateAsync({
    "user": user
  }, {
    "$pull": { "content": { "hash": content.hash } },
  })
}
}).then(function(){
  return users.updateAsync({
    "user": user,
  }, {
    "$push": {"content": content}
  })
})

Answer 1

Not entirely sure what your data looks like, but I think it's very close to the answer I gave in another thread. TLDR; unique sub-documents.

https://stackoverflow.com/a/29102690/1058776

---

This comes up in google so I thought I'd add an alternative to using an index to achieve unique key constraint like functionality in subdocuments, hope that's OK.

I'm not terribly familiar with Mongoose so it's just a mongo console update:

var foo = { _id: 'some value' }; //Your new subdoc here

db.yourCollection.update(
{ '_id': 'your query here', 'myArray._id': { '$ne': foo._id } },
{ '$push': { myArray: { foo } })

With documents looking like:

{
  _id: '...',
  myArray: [{_id:'your schema here'}, {...}, ...]
}

The key being that you ensure update will not return a document to update (ie the find part) if your subdocument key already exists.