initial public commit

tools/search/sort.go

@@ -0,0 +1,59 @@
+package search
+
+import (
+	"fmt"
+	"strings"
+)
+
+// sort field directions
+const (
+	SortAsc  string = "ASC"
+	SortDesc string = "DESC"
+)
+
+// SortField defines a single search sort field.
+type SortField struct {
+	Name      string `json:"name"`
+	Direction string `json:"direction"`
+}
+
+// BuildExpr resolves the sort field into a valid db sort expression.
+func (s *SortField) BuildExpr(fieldResolver FieldResolver) (string, error) {
+	name, params, err := fieldResolver.Resolve(s.Name)
+
+	// invalidate empty fields and non-column identifiers
+	if err != nil || len(params) > 0 || name == "" || strings.ToLower(name) == "null" {
+		return "", fmt.Errorf("Invalid sort field %q.", s.Name)
+	}
+
+	return fmt.Sprintf("%s %s", name, s.Direction), nil
+}
+
+// ParseSortFromString parses the provided string expression
+// into a slice of SortFields.
+//
+// Example:
+//	fields := search.ParseSortFromString("-name,+created")
+func ParseSortFromString(str string) []SortField {
+	result := []SortField{}
+
+	data := strings.Split(str, ",")
+
+	for _, field := range data {
+		// trim whitespaces
+		field = strings.TrimSpace(field)
+
+		var dir string
+		if strings.HasPrefix(field, "-") {
+			dir = SortDesc
+			field = strings.TrimPrefix(field, "-")
+		} else {
+			dir = SortAsc
+			field = strings.TrimPrefix(field, "+")
+		}
+
+		result = append(result, SortField{field, dir})
+	}
+
+	return result
+}