Implement db struct scanner

server/internal/db/scanner.go

@@ -0,0 +1,95 @@
+package db
+
+import (
+	"database/sql"
+	"fmt"
+	"reflect"
+)
+
+// Scanner provides methods for scanning rows into structs
+type Scanner struct {
+	db     *sql.DB
+	dbType DBType
+}
+
+// NewScanner creates a new Scanner instance
+func NewScanner(db *sql.DB, dbType DBType) *Scanner {
+	return &Scanner{
+		db:     db,
+		dbType: dbType,
+	}
+}
+
+// QueryRow executes a query and scans the result into a struct
+func (s *Scanner) QueryRow(dest interface{}, q *Query) error {
+	row := s.db.QueryRow(q.String(), q.Args()...)
+	return scanStruct(row, dest)
+}
+
+// Query executes a query and scans multiple results into a slice of structs
+func (s *Scanner) Query(dest interface{}, q *Query) error {
+	rows, err := s.db.Query(q.String(), q.Args()...)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	return scanStructs(rows, dest)
+}
+
+// scanStruct scans a single row into a struct
+func scanStruct(row *sql.Row, dest interface{}) error {
+	v := reflect.ValueOf(dest)
+	if v.Kind() != reflect.Ptr {
+		return fmt.Errorf("dest must be a pointer to a struct")
+	}
+	v = v.Elem()
+	if v.Kind() != reflect.Struct {
+		return fmt.Errorf("dest must be a pointer to a struct")
+	}
+
+	fields := make([]interface{}, 0, v.NumField())
+
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		if field.CanSet() {
+			fields = append(fields, field.Addr().Interface())
+		}
+	}
+
+	return row.Scan(fields...)
+}
+
+// scanStructs scans multiple rows into a slice of structs
+func scanStructs(rows *sql.Rows, dest interface{}) error {
+	v := reflect.ValueOf(dest)
+	if v.Kind() != reflect.Ptr {
+		return fmt.Errorf("dest must be a pointer to a slice")
+	}
+	sliceVal := v.Elem()
+	if sliceVal.Kind() != reflect.Slice {
+		return fmt.Errorf("dest must be a pointer to a slice")
+	}
+
+	elemType := sliceVal.Type().Elem()
+
+	for rows.Next() {
+		newElem := reflect.New(elemType).Elem()
+		fields := make([]interface{}, 0, newElem.NumField())
+
+		for i := 0; i < newElem.NumField(); i++ {
+			field := newElem.Field(i)
+			if field.CanSet() {
+				fields = append(fields, field.Addr().Interface())
+			}
+		}
+
+		if err := rows.Scan(fields...); err != nil {
+			return err
+		}
+
+		sliceVal.Set(reflect.Append(sliceVal, newElem))
+	}
+
+	return rows.Err()
+}