Method BuildExpr

tools/search/sort.go:26–45

BuildExpr resolves the sort field into a valid db sort expression.

(fieldResolver FieldResolver)

// BuildExpr resolves the sort field into a valid db sort expression.
func (s *SortField) BuildExpr(fieldResolver FieldResolver) (string, error) {
	// special case for random sort
	if s.Name == randomSortKey {
		return "RANDOM()", nil
	}

	// special case for the builtin SQLite rowid column
	if s.Name == rowidSortKey {
		return fmt.Sprintf("[[_rowid_]] %s", s.Direction), nil
	}

	result, err := fieldResolver.Resolve(s.Name)

	// invalidate empty fields and non-column identifiers
	if err != nil || len(result.Params) > 0 || result.Identifier == "" || strings.ToLower(result.Identifier) == "null" {
		return "", fmt.Errorf("invalid sort field %q", s.Name)
	}

	return fmt.Sprintf("%s %s", result.Identifier, s.Direction), nil
}

// ParseSortFromString parses the provided string expression
// into a slice of SortFields.