1.support dynamic registration model

2.support aggregete func

client/orm/db.go

@@ -948,9 +948,10 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 	val := reflect.ValueOf(container)
 	ind := reflect.Indirect(val)
 
-	errTyp := true
+	unregister := true
 	one := true
 	isPtr := true
+	name := ""
 
 	if val.Kind() == reflect.Ptr {
 		fn := ""
@@ -963,19 +964,17 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 			case reflect.Struct:
 				isPtr = false
 				fn = getFullName(typ)
+				name = getTableName(reflect.New(typ))
 			}
 		} else {
 			fn = getFullName(ind.Type())
+			name = getTableName(ind)
 		}
-		errTyp = fn != mi.fullName
+		unregister = fn != mi.fullName
 	}
 
-	if errTyp {
-		if one {
-			panic(fmt.Errorf("wrong object type `%s` for rows scan, need *%s", val.Type(), mi.fullName))
-		} else {
-			panic(fmt.Errorf("wrong object type `%s` for rows scan, need *[]*%s or *[]%s", val.Type(), mi.fullName, mi.fullName))
-		}
+	if unregister {
+		RegisterModel(container)
 	}
 
 	rlimit := qs.limit
@@ -1040,6 +1039,9 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 	if qs.distinct {
 		sqlSelect += " DISTINCT"
 	}
+	if qs.aggregate != "" {
+		sels = qs.aggregate
+	}
 	query := fmt.Sprintf("%s %s FROM %s%s%s T0 %s%s%s%s%s%s",
 		sqlSelect, sels, Q, mi.table, Q,
 		specifyIndexes, join, where, groupBy, orderBy, limit)
@@ -1064,16 +1066,20 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 		}
 	}
 
+	defer rs.Close()
+
+	slice := ind
+	if unregister {
+		mi, _ = modelCache.get(name)
+		tCols = mi.fields.dbcols
+		colsNum = len(tCols)
+	}
+
 	refs := make([]interface{}, colsNum)
 	for i := range refs {
 		var ref interface{}
 		refs[i] = &ref
 	}
-
-	defer rs.Close()
-
-	slice := ind
-
 	var cnt int64
 	for rs.Next() {
 		if one && cnt == 0 || !one {