How to delete subdocument but keep contents in mongodb - json

Question

I ran a script that populated my collection with approximately 60k documents. Because of a mistype, it created subdocuments within all of the documents and contains duplicate information. I really don't need/want the subdocument, but I don't want to delete the it entirely, because I want a field within it to remain.
This is my document structure
{
"_id" : ObjectId(""),
"title" : "",
"url" : "",
"description" : "",
"author" : "",
"publishedAt" : "",
"content" : ""
"source" : {
"id" : "Source",
"name" : "Source"
},
"urlToImage" : ""
}
Ultimately what I want to do, if possible, is remove the source subdocument, but keep the name field. Below is what I want.
{
"_id" : ObjectId(""),
"title" : "",
"url" : "",
"description" : "",
"author" : "",
"publishedAt" : "",
"content" : ""
"name" : "Source"
"urlToImage" : ""
}
I know this would be a multi-part query. I just don't want to make a mistake and delete the entire subdocument without pulling out the fields first.

Answer 1

option 1 - $rename and $unset
use $rename operator to rename source.name to name
perhaps with some check (filter) that you are not going to overwrite existing name with null
then remove the source subdocument using $unset operator
again, just to be sure, you can add filter to make sure that the name field already exists in document where you are unsetting the source
option 2 - find and $set+$unset
retrieve the document
update the document using $set and $unset
Example (in Python):
while True:
doc = db.find_one({
'_id': 'foobar',
'source.name': {'$exists': True},
})
res = db.update_one(
{
'_id': 'foobar',
'source.name': doc['source']['name'],
}, {
'$set': {'name': doc['source']['name']},
'$unset': {'source': ''},
}
)
if res.modified_count == 1:
break
# if nothing was modified then somebody has updated
# the source.name right after our find_one()