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62 lines
1.2 KiB
62 lines
1.2 KiB
package dts
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import (
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"database/sql"
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"database/sql/driver"
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"encoding/json"
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)
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// NullString represents a string that may be null.
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// NullString implements the [Scanner] interface so
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// it can be used as a scan destination:
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//
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// var s NullString
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// err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&s)
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// ...
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// if s.Valid {
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// // use s.String
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// } else {
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// // NULL value
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// }
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type NullString struct {
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String string
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Valid bool // Valid is true if String is not NULL
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}
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// Scan implements the Scanner interface.
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func (ns *NullString) Scan(value any) error {
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if value == nil {
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ns.String, ns.Valid = "", false
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return nil
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}
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ss := new(sql.NullString)
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err := ss.Scan(value)
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ns.String = ss.String
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ns.Valid = ss.Valid
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return err
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}
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// Value implements the driver Valuer interface.
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func (ns NullString) Value() (driver.Value, error) {
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if !ns.Valid {
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return nil, nil
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}
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return ns.String, nil
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}
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func (ns NullString) MarshalJSON() ([]byte, error) {
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if ns.Valid {
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return json.Marshal(ns.String)
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}
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return json.Marshal(nil)
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}
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func (ns *NullString) UnmarshalJSON(b []byte) error {
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if string(b) == "null" {
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ns.Valid = false
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return nil
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}
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err := json.Unmarshal(b, &ns.String)
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ns.Valid = err == nil
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return err
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}
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