Go Mongo Update NonZero values only - mongodb

Question

How to update the document with non zero values only. As example I didn't received any value for status and Struct has only two values to be updated. So it should only update those 2 values and skip zero/null values. But as given below it's updating it to zero/null/""
type Product struct {
ID primitive.ObjectID `json:"id" bson:"_id"`
Status int `json:"status" bson:"status"`
DisplayName string `json:"displayName" bson:"display_name"`
Text string `json:"text" bson:"text"`
}
I have tried the following up it's overriding the status value to 0 if no value is passed for it.
opts := options.Update().SetUpsert(false)
filter := bson.D{primitive.E{Key: "_id", Value: product.ID}}
update := bson.D{{"$set", bson.D{{"status", product.Status}, bson.D{{"text",product.Text}, {"display_name", product.DisplayName}}}}
_, err := db.Collection("product").UpdateOne(context.TODO(), filter, update, opts)
How to achieve this cleanly without ifs. For any struct in Service.

Answer 1

First, your update document should not contain an embedded document if Product is the Go struct that models your documents. It should be:
update := bson.D{
{"$set", bson.D{
{"status", product.Status},
{"text", product.Text},
{"display_name", product.DisplayName},
}},
}
Now on to your issue. You explicitly tell in the update document to set them to their zero value, so that's what MongoDB does.
If you don't want to set zero values, don't add them to the update document. Build your update document like this:
setDoc := bson.D{}
if product.Status != 0 {
setDoc = append(setDoc, bson.E{"status", product.Status})
}
if product.Text != "" {
setDoc = append(setDoc, bson.E{"text", product.Text})
}
if product.DisplayName != "" {
setDoc = append(setDoc, bson.E{"display_name", product.DisplayName})
}
update := bson.D{{"$set", setDoc}}
Note that you can achieve the same if you use the ,omitempty BSON tag option and use / pass a Product struct value for the setDoc:
type Product struct {
ID primitive.ObjectID `json:"id" bson:"_id"`
Status int `json:"status" bson:"status,omitempty"`
DisplayName string `json:"displayName" bson:"display_name,omitempty"`
Text string `json:"text" bson:"text,omitempty"`
}
And then simply:
update := bson.D{{"$set", product}}