I have a DynamoDB table with a model that contains and itemData property of type Map that contains count and limit properties.

"NonKeyAttributes": [
  {
    "AttributeName": "creationDate",
    "AttributeType": "N"
  },
  {
    "AttributeName": "modificationDate",
    "AttributeType": "N"
  },
  {
    "AttributeName": "itemData",
    "AttributeType": "M"
  }
],

I am trying to write a condition check that looks like this:

UpdateExpression: 'set itemData.count = itemData.count + :val',
ConditionExpression: 'itemData.count < itemData.limit',
ExpressionAttributeValues: {
    ':val': 1
}

My problem is that the conditional check fails, regardless the values of count and limit, here are the current values pulled from row.

  "limit": {
    "N": "1"
  },
  "count": {
    "N": "0"
  },

Is this even allowed? I have been pulling my hair out on this for a while now.

I have also run the condition against my root level creationTime/modificationTime properties, and that conditional check works fine. I am really hoping I can do the condition on the property within the map.