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