Remove the gorm dependency from the Update func

kiss_orm.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"reflect"
+	"strings"
 
 	"github.com/jinzhu/gorm"
 )
@@ -241,20 +242,62 @@ func (c Client) Update(
 	records ...interface{},
 ) error {
 	for _, record := range records {
-		m, err := StructToMap(record)
+		query, params, err := buildUpdateQuery(c.tableName, record, "id")
 		if err != nil {
 			return err
 		}
-		delete(m, "id")
-		r := c.db.Table(c.tableName).Model(record).Updates(m)
-		if r.Error != nil {
-			return r.Error
+
+		_, err = c.db.DB().Exec(query, params...)
+		if err != nil {
+			return err
 		}
 	}
 
 	return nil
 }
 
+func buildUpdateQuery(
+	tableName string,
+	record interface{},
+	idFieldNames ...string,
+) (query string, args []interface{}, err error) {
+	recordMap, err := StructToMap(record)
+	if err != nil {
+		return "", nil, err
+	}
+	numAttrs := len(recordMap)
+	numIDs := len(idFieldNames)
+	args = make([]interface{}, numAttrs+numIDs)
+	whereArgs := args[numAttrs-1:]
+
+	var whereQuery []string
+	for i, fieldName := range idFieldNames {
+		whereArgs[i] = recordMap[fieldName]
+		whereQuery = append(whereQuery, fmt.Sprintf("`%s` = ?", fieldName))
+		delete(recordMap, fieldName)
+	}
+
+	keys := []string{}
+	for key := range recordMap {
+		keys = append(keys, key)
+	}
+
+	var setQuery []string
+	for i, k := range keys {
+		args[i] = recordMap[k]
+		setQuery = append(setQuery, fmt.Sprintf("`%s` = ?", k))
+	}
+
+	query = fmt.Sprintf(
+		"UPDATE `%s` SET %s WHERE %s",
+		tableName,
+		strings.Join(setQuery, ", "),
+		strings.Join(whereQuery, ", "),
+	)
+
+	return query, args, nil
+}
+
 // This cache is kept as a pkg variable
 // because the total number of types on a program
 // should be finite. So keeping a single cache here