Use struct tags to get database column name

db.go

package db
​
import (
	"database/sql"
	"database/sql/driver"
	"fmt"
	"reflect"
	"app/config"
	"strings"
​
	_ "github.com/lib/pq"
)
​
type DSNOption struct {
	Key   string
	Value string
}
​
func NewDB(cfg config.DB) (*sql.DB, error) {
	return sql.Open(
		"postgres",
		fmt.Sprintf(
			"postgres://%s:%s@%s/%s?%s",
			cfg.User,
			cfg.Password,
			cfg.Host,
			cfg.DBName,
			strings.Join(cfg.DSNOptions, "&"),
		),
	)
}
​
// ColumnDataPair describes a piece of data that is stored in a database table column
type ColumnDataPair struct {
	Column string
	Data   interface{}
}
​
// GetFields returns you an array of ColumnDataPairs which describe
// a database row.
// It uses the db struct tag to get the table column names
func GetFields(s interface{}) ([]ColumnDataPair, error) {
	var row []ColumnDataPair
	t := reflect.TypeOf(s)
	v := reflect.ValueOf(s)
​
	for i := 0; i < t.NumField(); i++ {
		field := t.Field(i)
		col := field.Tag.Get("db")
		if col == "" {
			col = field.Name
		}
​
		val, err := driver.DefaultParameterConverter.ConvertValue(v.Field(i).Interface())
		if err != nil {
			return nil, err
		}
		row = append(row, ColumnDataPair{col, val})
	}
	return row, nil
}

db_test.go

package db
​
import (
	"reflect"
	"testing"
)
​
func TestGetFields(t *testing.T) {
	type args struct {
		s interface{}
	}
	tests := []struct {
		name    string
		args    args
		want    []ColumnDataPair
		wantErr bool
	}{
		{
			"Returns the columns in the correct order",
			args{
				struct {
					String    string `db:"column"`
					SpecialID int    `db:"id"`
				}{
					String:    "whatever",
					SpecialID: 1234,
				},
			},
			[]ColumnDataPair{{"column", "whatever"}, {"id", int64(1234)}},
			false,
		},
	}
	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()
			got, err := GetFields(tt.args.s)
			if (err != nil) != tt.wantErr {
				t.Errorf("GetFields() error = %v, wantErr %v", err, tt.wantErr)
				return
			}
			if !reflect.DeepEqual(got, tt.want) {
				t.Errorf("GetFields() got = %v, want %v", got, tt.want)
			}
		})
	}
}