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uint32.go
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uint32.go
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package null
import (
"database/sql/driver"
"encoding/json"
"fmt"
"reflect"
"strconv"
)
// Uint32 encapsulates the value and validity (not null) of a uint32 value,
// to differentiate nil from 0 in json and sql.
type Uint32 struct {
Uint32 uint32
Valid bool
}
// NewUint32 returns an instance of Uint32 with the passed parameters.
func NewUint32(i uint32, valid bool) Uint32 {
return Uint32{
Uint32: i,
Valid: valid,
}
}
// Uint32From creates a new Uint32 that will always be valid.
func Uint32From(i uint32) Uint32 {
return NewUint32(i, true)
}
// UnmarshalJSON implements json.Unmarshaler.
// It supports number and null input.
// 0 will not be considered a null Int.
func (i *Uint32) UnmarshalJSON(data []byte) error {
var err error
var v interface{}
if err = json.Unmarshal(data, &v); err != nil {
return err
}
switch x := v.(type) {
case float64:
// Unmarshal again, directly to value, to avoid intermediate float64
err = json.Unmarshal(data, &i.Uint32)
case string:
str := string(x)
if len(str) == 0 {
i.Valid = false
return nil
}
i.Uint32, err = parse(str)
case nil:
i.Valid = false
return nil
default:
err = fmt.Errorf("json: cannot unmarshal %v into Go value of type null.Uint32", reflect.TypeOf(v).Name())
}
i.Valid = err == nil
return err
}
// UnmarshalText implements encoding.TextUnmarshaler.
// It will unmarshal to a null Uint32 if the input is a blank or not an integer.
// It will return an error if the input is not an integer, blank, or "null".
func (i *Uint32) UnmarshalText(text []byte) error {
str := string(text)
if str == "" || str == "null" {
i.Valid = false
return nil
}
var err error
i.Uint32, err = parse(string(text))
i.Valid = err == nil
return err
}
func parse(str string) (uint32, error) {
v, err := strconv.ParseUint(str, 10, 32)
return uint32(v), err
}
// MarshalJSON implements json.Marshaler.
// It will encode null if this Uint32 is null.
func (i Uint32) MarshalJSON() ([]byte, error) {
if !i.Valid {
return []byte("null"), nil
}
return []byte(strconv.FormatUint(uint64(i.Uint32), 10)), nil
}
// MarshalText implements encoding.TextMarshaler.
// It will encode a blank string if this Uint32 is null.
func (i Uint32) MarshalText() ([]byte, error) {
if !i.Valid {
return []byte{}, nil
}
return []byte(strconv.FormatUint(uint64(i.Uint32), 10)), nil
}
// SetValid changes this Uint32's value and also sets it to be non-null.
func (i *Uint32) SetValid(n uint32) {
i.Uint32 = n
i.Valid = true
}
// Value returns this instance serialized for database storage.
func (i Uint32) Value() (driver.Value, error) {
if !i.Valid {
return nil, nil
}
// golang's sql driver types as determined by IsValue only supports:
// []byte, bool, float64, int64, string, time.Time
// https://golang.org/src/database/sql/driver/types.go
return int64(i.Uint32), nil
}
// Scan reads the database value and returns an instance.
func (i *Uint32) Scan(value interface{}) error {
if value == nil {
*i = Uint32{}
return nil
}
switch typed := value.(type) {
case int:
safe := uint32(typed)
if int(safe) != typed {
return fmt.Errorf("unable to convert %v of %T to Uint32; overflow", value, value)
}
*i = Uint32From(safe)
case int64:
safe := uint32(typed)
if int64(safe) != typed {
return fmt.Errorf("unable to convert %v of %T to Uint32; overflow", value, value)
}
*i = Uint32From(safe)
case uint:
safe := uint32(typed)
if uint(safe) != typed {
return fmt.Errorf("unable to convert %v of %T to Uint32; overflow", value, value)
}
*i = Uint32From(safe)
case uint32:
safe := typed
*i = Uint32From(safe)
default:
return fmt.Errorf("unable to convert %v of %T to Uint32", value, value)
}
return nil
}