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int64.go
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int64.go
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package null
import (
"database/sql/driver"
"encoding/json"
"fmt"
"math"
"reflect"
"strconv"
)
// Int64 encapsulates the value and validity (not null) of a int64 value,
// to differentiate nil from 0 in json and sql.
type Int64 struct {
Int64 int64
Valid bool
}
// NewInt64 returns an instance of Int64 with the passed parameters.
func NewInt64(i int64, valid bool) Int64 {
return Int64{
Int64: i,
Valid: valid,
}
}
// Int64From creates a new Int64 that will always be valid.
func Int64From(i int64) Int64 {
return NewInt64(i, true)
}
// UnmarshalJSON implements json.Unmarshaler.
// It supports number and null input.
// 0 will not be considered a null Int.
func (i *Int64) 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.Int64)
case string:
str := string(x)
if len(str) == 0 {
i.Valid = false
return nil
}
i.Int64, err = parse64(str)
case nil:
i.Valid = false
return nil
default:
err = fmt.Errorf("json: cannot unmarshal %v into Go value of type null.Int64", reflect.TypeOf(v).Name())
}
i.Valid = err == nil
return err
}
// UnmarshalText implements encoding.TextUnmarshaler.
// It will unmarshal to a null Int64 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 *Int64) UnmarshalText(text []byte) error {
str := string(text)
if str == "" || str == "null" {
i.Valid = false
return nil
}
var err error
i.Int64, err = parse64(string(text))
i.Valid = err == nil
return err
}
func parse64(str string) (int64, error) {
v, err := strconv.ParseInt(str, 10, 64)
return v, err
}
// MarshalJSON implements json.Marshaler.
// It will encode null if this Int64 is null.
func (i Int64) MarshalJSON() ([]byte, error) {
if !i.Valid {
return []byte("null"), nil
}
return []byte(strconv.FormatInt(int64(i.Int64), 10)), nil
}
// MarshalText implements encoding.TextMarshaler.
// It will encode a blank string if this Int64 is null.
func (i Int64) MarshalText() ([]byte, error) {
if !i.Valid {
return []byte{}, nil
}
return []byte(strconv.FormatInt(int64(i.Int64), 10)), nil
}
// SetValid changes this Int64's value and also sets it to be non-null.
func (i *Int64) SetValid(n int64) {
i.Int64 = n
i.Valid = true
}
// Value returns this instance serialized for database storage.
func (i Int64) 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.Int64), nil
}
// Scan reads the database value and returns an instance.
func (i *Int64) Scan(value interface{}) error {
if value == nil {
*i = Int64{}
return nil
}
switch typed := value.(type) {
case int:
safe := int64(typed)
*i = Int64From(safe)
case int32:
safe := int64(typed)
*i = Int64From(safe)
case int64:
safe := int64(typed)
*i = Int64From(safe)
case uint:
if typed > uint(math.MaxInt64) {
return fmt.Errorf("unable to convert %v of %T to Int64; overflow", value, value)
}
safe := int64(typed)
*i = Int64From(safe)
case uint64:
if typed > uint64(math.MaxInt64) {
return fmt.Errorf("unable to convert %v of %T to Int64; overflow", value, value)
}
safe := int64(typed)
*i = Int64From(safe)
default:
return fmt.Errorf("unable to convert %v of %T to Int64", value, value)
}
return nil
}