bson cannot Decode to nil value with bson:"omitempty" struct tag-CodePudding

I have a struct:

type User struct {
    ID        primitive.ObjectID `json:"id" bson:"_id,omitempty"`
    Username  *string            `json:"username" bson:"username,omitempty"`
    FirstName *string            `json:"firstName" bson:"first_name,omitempty"`
    LastName  *string            `json:"lastName" bson:"last_name,omitempty"`
    Email     *string            `json:"email" bson:"email,omitempty"`
    GoogleID  *string            `json:"googleID" bson:"google_id,omitempty"`
    PageURLs  []string           `json:"pageURLs" bson:"pages"`
    Schema    int                `json:"-" bson:"schema"` // omitted from graphql
}

I'm calling this code:

updateOption := options.FindOneAndUpdate().SetUpsert(true)

updateData := bson.M{"$set": *user}

filter := bson.M{"google_id": user.GoogleID}

// updated user will have Id
err = findOneUserAndUpdate(context.TODO(), filter, updateData, updateOption).Decode(updatedUser)

With the following user:

var testFirstname = "first"
var testLastname = "last"
var testEmail = "[email protected]"
var testGoogleID = "abc123"
testUser = &model.User{
    FirstName: &testFirstname,
    LastName:  &testLastname,
    Email:     &testEmail,
    GoogleID:  &testGoogleID,
    PageURLs:  []string{},
    Schema:    1,
}

but I'm getting this error saying: cannot Decode to nil value. This is probably because a pointer is nil, but the omitempty build tag should just omit the field in that case. Why would it fail to do so?

CodePudding user response：

updatedUser is what cannot be nil, you need to give it an empty struct at least to decode into.

CodePudding user response：

Seems like updateData := bson.M{"$set": *user} is not valid string. You can try updateData := bson.M{"$set": &user} that seems to work.