I have a collection of documents like this one:

{
    "_id" : ObjectId("..."),
    "field1": "some string",
    "field2": "another string",
    "field3": 123
}

I'd like to be able to iterate over the entire collection, and find the entire number of fields there are. In this example document there are 3 (I don't want to include _id), but it ranges from 2 to 50 fields in a document. Ultimately, I'm just looking for the average number of fields per document.

Any ideas?

mongodb mongodb-query
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