How to do multi-level pull of array element in mgo? - go

Question

I want to do a multi-level array element delete. My Structs are as follows:-
type Company struct {
Id bson.ObjectId `bson:"_id,omitempty"`
CompanyName string
Process []ProcessItem
}
type ProcessItem struct{
SortOrder int
Documents []DocumentTemplate
}
type DocumentTemplate struct {
Id bson.ObjectId `bson:"_id,omitempty"`
TemplateName string
}
I want to delete an object of type DocumentTemplate. The DocumentTemplate is a struct array in ProcessItem which is a struct array in Company struct. I have Company Id(field of struct Company) and TemplateName(field of struct DocumentTemplate).
I tried the below mgo pull query but it is not working.
c := db.C("company")
pullQuery := bson.M{"process": bson.M{"documents.templatename": "xyz"}}
err := c.Update(bson.M{"_id": "123"}, bson.M{"$pull": pullQuery})
Please point out the mistakes I made here. Thanks.
Edit:
Adding one example document for the clarity of the question
{
"_id" : ObjectId("573da7dddd73171e42a84045"),
"companyname" : "AAA",
"process" : [
{
"processname" : "Enquiry",
"sortorder" : 0,
"documents" : [
{
"templatename" : "xyz",
"processname" : "Enquiry"
},
{
"templatename" : "ss",
"processname" : "Enquiry"
}
]
},
{
"processname" : "Converted",
"processtype" : 1,
"sortorder" : 2,
"documents" : [
{
"templatename" : "dd",
"processname" : "Converted"
},
{
"templatename" : "fg",
"processname" : "Converted"
}
]
}
]
}
I need to pull out just one DocumentTemplete record, like the one below:
{
"templatename" : "xyz",
"processname" : "Enquiry"
}
N.B: TemplateName will be unique inside a Company.

Answer 1

You'll need to use the $ positional operator (https://docs.mongodb.com/manual/reference/operator/projection/positional/). In order to be able to use that you'll also have to add to your query the following:
"process.documents.templatename": "xyz"
Your Update statement should look like this:
c := db.C("company")
pullQuery := bson.M{"process.$.documents": bson.M{"templatename": "xyz"}}
err := c.Update(bson.M{"_id": "123", "process.documents.templatename": "xyz"}, bson.M{"$pull": pullQuery})

Answer 2

You can pull values in array from the array in mongo record
change2 := bson.M{
"$pull": bson.M{"sapinfo.systemstatus": bson.M{"$in": tags}},
}