func (b *Backend) filterItem(info *db.ModelInfo, item *reflector.Reflector, filter Expression) (bool, apperror.Error) {
switch f := filter.(type) {
case *AndExpr:
// Check each filter.
for _, e := range f.Expressions() {
flag, err := b.filterItem(info, item, e)
if err != nil {
return false, err
} else if !flag {
// One filter does not match, so return false.
return false, nil
}
}
// All filters matched, we can return true.
return true, nil
case *OrExpr:
// Check each filter.
for _, e := range f.Expressions() {
flag, err := b.filterItem(info, item, e)
if err != nil {
return false, err
} else if flag {
// One match is enough, so return true.
return true, nil
}
}
// No filters matched, so return false.
return false, nil
case *NotExpr:
// Reverse nested filter.
flag, err := b.filterItem(info, item, f.Not())
if err != nil {
return false, err
} else {
return !flag, nil
}
case FilterExpression:
field := f.Field()
fieldName := ""
if id, ok := field.(*IdentifierExpr); ok {
fieldName = id.Identifier()
} else if id, ok := field.(*ColFieldIdentifierExpr); ok {
if id.Collection() != info.Collection() {
return false, apperror.New("unsupported_filter", fmt.Sprint("The memory backend does not support filtering with joined collections"))
}
fieldName = id.Field()
} else {
return false, apperror.New("unsupported_filter", fmt.Sprintf("The memory backend does not support filtering with custom field expressions"))
}
attr := info.FindAttribute(fieldName)
if attr == nil {
return false, apperror.New("invalid_filter", fmt.Sprintf("Invalid filter for inexistant field %v", fieldName))
}
operator := f.Operator()
var clauseValue interface{}
if valExpr, ok := f.Clause().(*ValueExpr); ok {
clauseValue = valExpr.Value()
} else {
return false, apperror.New("unsupported_filter_clause", fmt.Sprintf("The memory backend does not support filtering with custom clause expressions"))
}
if info.StructName() != "" {
b.Logger().Infof("filtering item with %v %v %v", fieldName, operator, clauseValue)
s, err := item.Struct()
if err != nil {
return false, apperror.Wrap(err, "invalid_model_error")
}
flag, err := s.Field(attr.Name()).CompareTo(clauseValue, operator)
if err != nil {
return false, apperror.Wrap(err, "compare_error")
}
return flag, nil
} else {
// Assume a map.
if !item.IsMap() {
return false, apperror.New("filter_invalid_model", "Could not filter because model value is neither struct nor map.")
}
flag, err := reflector.R(item.Value().MapIndex(reflect.ValueOf(attr.BackendName()))).CompareTo(clauseValue, operator)
if err != nil {
return false, apperror.Wrap(err, "compare_error")
}
return flag, nil
}
default:
b.Logger().Panicf("Unhandled filter expression: %v", reflect.TypeOf(filter))
}
return false, nil
}
