This is with reference to
How to remove a document inside an array in mongodb using $pull
I need to remove empty sub arrays. I need to code this query in go lang
db.getCollection('workflows').update({<find condition>}, {$pull: {"workflows":[] } } )
So I've written the below code
nquery := bson.D {
{"level", "application"},
{"workflowName", workflowName},
{"applicationName", applicationName},
}
nupdate := bson.M{"$pull": bson.M{"workflows":"[]"}}
UpdateOne(getContext(), nquery, nupdate)
The result of UpdateOne shows my query has matched but hasn't modified anything. So I'm guessing there is some problem with the nupdate. What am I doing wrong ?
The UpdateOne function is part of the mongo-driver for go lang
"[]" is not an empty array in the query, it's a string having an opening and closing square brackets.
The MongoDB empty array can be "modeled" with an empty slice in Go, e.g. with a value of type []interface{}, so a composite literal of this type is []interface{}{}.
So use this:
nupdate := bson.M{"$pull": bson.M{"workflows": []interface{}{}}}
The square brackets "[]" shall not be in quotes since now they are interpreted as string ... , they need to be added just as square brackets [] and require in golang: &[]int{} to be translated by the mongo goland driver to empty array ...