A have a collection Products in MongoDB:

{
  "name": "My Product 01",
  "description": "This is an excelent product", 
  "tags": [
    "AA",
    "BBBB",
    "C",
    "DDDDDDDDDDD"
  ]  
}

How can I find the longest string in the array of tags of all objects inside this collection? (if I had only this object, the longest item would be “DDDDDDDDDDD” with 11 characters).