mongodb 将多个文档的字段类型改为数组

Question

I want to change the field type of several documents in one query.

This is some example data. The first example isn't scalable, what if person1 has more than one thing1 ?

This:

{ "name": "person1", "things": { "thing1": { "thingInstanceID": 400 } } }

should be:

{ "name": "person1", "things": { "thing1": [{ "thingInstanceID": 400 }] } }

I need to do this with hundreds of documents, and there's more than just thing1 , something like thing2 , thing3 , thing4 , etc. How can I do this?

Answer 1

For "thing1" to convert to array here is an option:

 db.collection.update({},
 [
  {
    $addFields: {
      "things": {
         thing1: [
          "$things.thing1"
         ]
       }
     }
   }
])

Explained:

Replace the field with array using aggregation pipeline( mongodb 4.2+ ) in the update operation

playground