Golang if statement not seeing 0 for int32

I have proto3/grpc function written in golang. There is a if statement written in a switch that does't see an int32 as a value of 0 when the value is a 0. I print the value before and it's a 0 but the if statement runs anyway. In my code below I have the output in a comment. I know for a int the nil value is a 0. If I place a value for the lname, fname they work as it should. Any help appreciated. Here is my output:

map[fname: lname: email: id:0]
0
id = $1

Here is my code:

func (s *server) GetUsers(ctx context.Context, in *userspb.User) (*userspb.Users, error) {
	flds := make(map[string]interface{})
	flds["id"] = in.Id // 0
	flds["fname"] = in.Fname // "" (empty)
	flds["lname"] = in.Lname // "" (empty)
	flds["email"] = in.Email // "" (empty)

	fmt.Println(flds) //map[lname: email: id:0 fname:]

	var where bytes.Buffer

	n := 0
	for _, v := range flds {
		switch v.(type) {
		case string:
			if v != "" {
				n++
			}
		case int, int32, int64:
			if v != 0 {
				n++
			}
		}
	}

	calledvariables := make([]interface{}, 0)

	i := 1
	for k, v := range flds {

		switch v.(type) {
		case string:
			if v != "" {
				if i != 1 {
					where.WriteString(" AND ")
				}
				ist := strconv.Itoa(i)
				where.WriteString(k + " = $" + ist)
				calledvariables = append(calledvariables, v)
				i++
			}
		case int, int32, int64, uint32, uint64:
			/////// THIS IF STATMENT IS THE ISSUE the ( v is printing the value of 0 and it's in the if statement )
			if v != 0 {
				fmt.Println(v) // 0
				if i != 1 {
					where.WriteString(" AND ")
				}
				ist := strconv.Itoa(i)
				where.WriteString(k + " = $" + ist)
				calledvariables = append(calledvariables, v)
				i++
			}
		}
	}

	fmt.Println(where.String()) // id = $1
    ...

Because the literal 0 is not the same type. If you do:

if v != int32(0) {

When the value is an int32, it works as expected. Unfortunately, you're combining all the int types in a single case, which will make this difficult/unwieldy to handle correctly. You could probably work something out using reflection to compare the value against the zero value for its type at runtime, using reflect.Zero.