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package gorm
import (
"errors"
"fmt"
"reflect"
)
// Define callbacks for querying
func init() {
DefaultCallback.Query().Register("gorm:query", queryCallback)
DefaultCallback.Query().Register("gorm:preload", preloadCallback)
DefaultCallback.Query().Register("gorm:after_query", afterQueryCallback)
}
// queryCallback used to query data from database
func queryCallback(scope *Scope) {
if _, skip := scope.InstanceGet("gorm:skip_query_callback"); skip {
return
}
//we are only preloading relations, dont touch base model
if _, skip := scope.InstanceGet("gorm:only_preload"); skip {
return
}
defer scope.trace(NowFunc())
var (
isSlice, isPtr bool
resultType reflect.Type
results = scope.IndirectValue()
)
if orderBy, ok := scope.Get("gorm:order_by_primary_key"); ok {
if primaryField := scope.PrimaryField(); primaryField != nil {
scope.Search.Order(fmt.Sprintf("%v.%v %v", scope.QuotedTableName(), scope.Quote(primaryField.DBName), orderBy))
}
}
if value, ok := scope.Get("gorm:query_destination"); ok {
results = indirect(reflect.ValueOf(value))
}
if kind := results.Kind(); kind == reflect.Slice {
isSlice = true
resultType = results.Type().Elem()
results.Set(reflect.MakeSlice(results.Type(), 0, 0))
if resultType.Kind() == reflect.Ptr {
isPtr = true
resultType = resultType.Elem()
}
} else if kind != reflect.Struct {
scope.Err(errors.New("unsupported destination, should be slice or struct"))
return
}
scope.prepareQuerySQL()
if !scope.HasError() {
scope.db.RowsAffected = 0
if str, ok := scope.Get("gorm:query_hint"); ok {
scope.SQL = fmt.Sprint(str) + scope.SQL
}
if str, ok := scope.Get("gorm:query_option"); ok {
scope.SQL += addExtraSpaceIfExist(fmt.Sprint(str))
}
if rows, err := scope.SQLDB().Query(scope.SQL, scope.SQLVars...); scope.Err(err) == nil {
defer rows.Close()
columns, _ := rows.Columns()
for rows.Next() {
scope.db.RowsAffected++
elem := results
if isSlice {
elem = reflect.New(resultType).Elem()
}
scope.scan(rows, columns, scope.New(elem.Addr().Interface()).Fields())
if isSlice {
if isPtr {
results.Set(reflect.Append(results, elem.Addr()))
} else {
results.Set(reflect.Append(results, elem))
}
}
}
if err := rows.Err(); err != nil {
scope.Err(err)
} else if scope.db.RowsAffected == 0 && !isSlice {
scope.Err(ErrRecordNotFound)
}
}
}
}
// afterQueryCallback will invoke `AfterFind` method after querying
func afterQueryCallback(scope *Scope) {
if !scope.HasError() {
scope.CallMethod("AfterFind")
}
}