Golang UPDATE column with Postgres

Let's say I have a table employments and a struct Employment

type Employment struct {
	ID              int     `json:"id"`
	Created_at      string  `json:"created_at"`
	Updated_at      string  `json:"updated_at"`
	Education       string  `json:"education"`
	Job             string  `json:"job"`
	Position        string  `json:"position"`
	Business_phone  string  `json:"business_phone"`
	Next_payday     string  `json:"next_payday"`
	Employment_type int     `json:"employment_type"`
	Income          float64 `json:"income"`
	Additional      float64 `json:"additional"`
}

User can update their employment, the problem is I don't know which fields user want to update.

So that, I decided to range over input struct to get non nil fields to generate query string, some thing like UPDATE employments SET position=$1, income=$2 WHERE id=$3

This is what I got this time

func FlexibleUpdate(table_name string, str interface{}, cond string, ret string) string {

	query := "UPDATE " + table_name + " SET "
	j := 0
	m := structs.Map(str)

	for i := range m {
		if m[i] != "" && m[i] != 0 && m[i] != 0.0 && {
			j++
			query = query + strings.ToLower(i) + "=$" + strconv.Itoa(j) + ","
		}
	}
	j++

	// adding conditions
	if cond != "" {
		query = query[:len(query)-1] + " WHERE " + cond + "=$" + strconv.Itoa(j)
	}

	// return values
	if ret != "" {
		query = query + " RETURNING " + ret
	}

	return query
}

I don't know how to assign input values to $1, $2, ... to execute query

database.DB.QueryRow(query_string, value_1, value_2, ...)

Let me know if you have any idea or another way to resolve it.

Just collect the non-nil values in a slice and then use that slice with ... when executing the query.

var values []interface{}
for i := range m {
    if v := m[i]; v != "" && v != 0 && v != 0.0 && /* you're missing a condition here */{
        j++
        query = query + strings.ToLower(i) + "=$" + strconv.Itoa(j) + ","
        values = append(values, v)
    }
}

// ....

database.DB.QueryRow(query_string, values...)