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QRM returns sql.ErrNoRows when scanning into struct destination and query result set is empty.

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This commit is contained in:
go-jet 2019-10-12 18:45:09 +02:00
parent 3544977d7f
commit f9efee77ff
7 changed files with 103 additions and 90 deletions
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98
qrm/qrm.go
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@ -10,6 +10,7 @@ import (
// Query executes Query Result Mapping (QRM) of `query` with list of parametrized arguments `arg` over database connection `db`
// using context `ctx` into destination `destPtr`.
// Destination can be either pointer to struct or pointer to slice of structs.
// If destination is pointer to struct and query result set is empty, method returns sql.ErrNoRows.
func Query(ctx context.Context, db DB, query string, args []interface{}, destPtr interface{}) error {
utils.MustBeInitializedPtr(db, "jet: db is nil")
@ -19,21 +20,27 @@ func Query(ctx context.Context, db DB, query string, args []interface{}, destPtr
destinationPtrType := reflect.TypeOf(destPtr)
if destinationPtrType.Elem().Kind() == reflect.Slice {
return queryToSlice(ctx, db, query, args, destPtr)
_, err := queryToSlice(ctx, db, query, args, destPtr)
return err
} else if destinationPtrType.Elem().Kind() == reflect.Struct {
tempSlicePtrValue := reflect.New(reflect.SliceOf(destinationPtrType))
tempSliceValue := tempSlicePtrValue.Elem()
err := queryToSlice(ctx, db, query, args, tempSlicePtrValue.Interface())
rowsProcessed, err := queryToSlice(ctx, db, query, args, tempSlicePtrValue.Interface())
if err != nil {
return err
}
if tempSliceValue.Len() == 0 {
if rowsProcessed == 0 {
return sql.ErrNoRows
}
// edge case when row result set contains only NULLs.
if tempSliceValue.Len() == 0 {
return nil
}
structValue := reflect.ValueOf(destPtr).Elem()
firstTempStruct := tempSliceValue.Index(0).Elem()
@ -46,7 +53,7 @@ func Query(ctx context.Context, db DB, query string, args []interface{}, destPtr
}
}
func queryToSlice(ctx context.Context, db DB, query string, args []interface{}, slicePtr interface{}) error {
func queryToSlice(ctx context.Context, db DB, query string, args []interface{}, slicePtr interface{}) (rowsProcessed int64, err error) {
if ctx == nil {
ctx = context.Background()
}
@ -54,27 +61,27 @@ func queryToSlice(ctx context.Context, db DB, query string, args []interface{},
rows, err := db.QueryContext(ctx, query, args...)
if err != nil {
return err
return
}
defer rows.Close()
scanContext, err := newScanContext(rows)
if err != nil {
return err
return
}
if len(scanContext.row) == 0 {
return nil
return
}
slicePtrValue := reflect.ValueOf(slicePtr)
for rows.Next() {
err := rows.Scan(scanContext.row...)
err = rows.Scan(scanContext.row...)
if err != nil {
return err
return
}
scanContext.rowNum++
@ -82,22 +89,24 @@ func queryToSlice(ctx context.Context, db DB, query string, args []interface{},
_, err = mapRowToSlice(scanContext, "", slicePtrValue, nil)
if err != nil {
return err
return
}
}
err = rows.Close()
if err != nil {
return err
return
}
err = rows.Err()
if err != nil {
return err
return
}
return nil
rowsProcessed = scanContext.rowNum
return
}
func mapRowToSlice(scanContext *scanContext, groupKey string, slicePtrValue reflect.Value, field *reflect.StructField) (updated bool, err error) {
@ -165,6 +174,7 @@ func mapRowToBaseTypeSlice(scanContext *scanContext, slicePtrValue reflect.Value
}
func mapRowToStruct(scanContext *scanContext, groupKey string, structPtrValue reflect.Value, parentField *reflect.StructField, onlySlices ...bool) (updated bool, err error) {
mapOnlySlices := len(onlySlices) > 0
structType := structPtrValue.Type().Elem()
typeInf := scanContext.getTypeInfo(structType, parentField)
@ -193,22 +203,21 @@ func mapRowToStruct(scanContext *scanContext, groupKey string, structPtrValue re
updated = true
}
} else if len(onlySlices) == 0 {
if fieldMap.columnIndex == -1 {
} else {
if mapOnlySlices || fieldMap.columnIndex == -1 {
continue
}
cellValue := scanContext.rowElem(fieldMap.columnIndex)
if cellValue == nil {
continue
}
initializeValueIfNilPtr(fieldValue)
updated = true
if fieldMap.implementsScanner {
cellValue := scanContext.rowElem(fieldMap.columnIndex)
if cellValue == nil {
continue
}
initializeValueIfNilPtr(fieldValue)
scanner := getScanner(fieldValue)
err = scanner.Scan(cellValue)
@ -216,15 +225,8 @@ func mapRowToStruct(scanContext *scanContext, groupKey string, structPtrValue re
if err != nil {
panic("jet: " + err.Error() + ", " + fieldToString(&field) + " of type " + structType.String())
}
updated = true
} else {
cellValue := scanContext.rowElem(fieldMap.columnIndex)
if cellValue != nil {
updated = true
initializeValueIfNilPtr(fieldValue)
setReflectValue(reflect.ValueOf(cellValue), fieldValue)
}
setReflectValue(reflect.ValueOf(cellValue), fieldValue)
}
}
}
@ -232,21 +234,6 @@ func mapRowToStruct(scanContext *scanContext, groupKey string, structPtrValue re
return
}
func mapRowToDestinationPtr(scanContext *scanContext, groupKey string, destPtrValue reflect.Value, structField *reflect.StructField) (updated bool, err error) {
utils.ValueMustBe(destPtrValue, reflect.Ptr, "jet: internal error. Destination is not pointer.")
destValueKind := destPtrValue.Elem().Kind()
if destValueKind == reflect.Struct {
return mapRowToStruct(scanContext, groupKey, destPtrValue, structField)
} else if destValueKind == reflect.Slice {
return mapRowToSlice(scanContext, groupKey, destPtrValue, structField)
} else {
panic("jet: unsupported dest type: " + structField.Name + " " + structField.Type.String())
}
}
func mapRowToDestinationValue(scanContext *scanContext, groupKey string, dest reflect.Value, structField *reflect.StructField) (updated bool, err error) {
var destPtrValue reflect.Value
@ -273,3 +260,18 @@ func mapRowToDestinationValue(scanContext *scanContext, groupKey string, dest re
return
}
func mapRowToDestinationPtr(scanContext *scanContext, groupKey string, destPtrValue reflect.Value, structField *reflect.StructField) (updated bool, err error) {
utils.ValueMustBe(destPtrValue, reflect.Ptr, "jet: internal error. Destination is not pointer.")
destValueKind := destPtrValue.Elem().Kind()
if destValueKind == reflect.Struct {
return mapRowToStruct(scanContext, groupKey, destPtrValue, structField)
} else if destValueKind == reflect.Slice {
return mapRowToSlice(scanContext, groupKey, destPtrValue, structField)
} else {
panic("jet: unsupported dest type: " + structField.Name + " " + structField.Type.String())
}
}