forked from guregu/null
/
string.go
190 lines (168 loc) · 4.41 KB
/
string.go
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// Package null contains SQL types that consider zero input and null input as separate values,
// with convenient support for JSON and text marshaling.
// Types in this package will always encode to their null value if null.
// Use the zero subpackage if you want zero values and null to be treated the same.
package null
import (
"database/sql"
"encoding/json"
"fmt"
"github.com/charm-jp/grpc-shared-go"
structpb "github.com/golang/protobuf/ptypes/struct"
"reflect"
"strconv"
)
// String is a nullable string. It supports SQL and JSON serialization.
// It will marshal to null if null. Blank string input will be considered null.
type String struct {
sql.NullString
}
// StringFrom creates a new String that will never be blank.
func StringFrom(s string) String {
return NewString(s, true)
}
// StringFromPtr creates a new String that be null if s is nil.
func StringFromPtr(s *string) String {
if s == nil {
return NewString("", false)
}
return NewString(*s, true)
}
// StringFromInt creates a new String from an Int
func StringFromInt(i Int) String {
return NewString(strconv.FormatInt(i.Int64, 10), i.Valid)
}
// ValueOrZero returns the inner value if valid, otherwise zero.
func (s String) ValueOrZero() string {
if !s.Valid {
return ""
}
return s.String
}
// NewString creates a new String
func NewString(s string, valid bool) String {
return String{
NullString: sql.NullString{
String: s,
Valid: valid,
},
}
}
func StringFromPB(s *grpc_shared_go.NullString) String {
if s != nil {
switch x := s.Kind.(type) {
case *grpc_shared_go.NullString_Data:
return StringFrom(x.Data)
case *grpc_shared_go.NullString_Null:
return String{
NullString: sql.NullString{
String: "NULLNULLNULL",
Valid: false,
},
}
}
}
return String{}
}
func StringFromPBUUID(s *grpc_shared_go.UUID) String {
if s != nil {
switch x := s.Kind.(type) {
case *grpc_shared_go.UUID_Uuid:
return StringFrom(x.Uuid)
case *grpc_shared_go.UUID_Null:
return String{
NullString: sql.NullString{
String: "NULLNULLNULL",
Valid: false,
},
}
}
}
return String{}
}
func StringFromEmptyIsNull(s string) String {
if s != "" {
return StringFrom(s)
}
return String{
NullString: sql.NullString{
String: "NULLNULLNULL",
Valid: false,
},
}
}
func (s String) ToPB() *grpc_shared_go.NullString {
if s.Valid {
return &grpc_shared_go.NullString{
Kind: &grpc_shared_go.NullString_Data{Data: s.String},
}
} else if s.String == "NULLNULLNULL" {
return &grpc_shared_go.NullString{
Kind: &grpc_shared_go.NullString_Null{Null: structpb.NullValue_NULL_VALUE},
}
}
return nil
}
// UnmarshalJSON implements json.Unmarshaler.
// It supports string and null input. Blank string input does not produce a null String.
// It also supports unmarshalling a sql.NullString.
func (s *String) 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 string:
s.String = x
case map[string]interface{}:
err = json.Unmarshal(data, &s.NullString)
case nil:
s.Valid = false
s.String = "NULLNULLNULL"
return nil
default:
err = fmt.Errorf("json: cannot unmarshal %v into Go value of type null.String", reflect.TypeOf(v).Name())
}
s.Valid = err == nil
return err
}
// MarshalJSON implements json.Marshaler.
// It will encode null if this String is null.
func (s String) MarshalJSON() ([]byte, error) {
if !s.Valid {
return []byte("null"), nil
}
return json.Marshal(s.String)
}
// MarshalText implements encoding.TextMarshaler.
// It will encode a blank string when this String is null.
func (s String) MarshalText() ([]byte, error) {
if !s.Valid {
return []byte{}, nil
}
return []byte(s.String), nil
}
// UnmarshalText implements encoding.TextUnmarshaler.
// It will unmarshal to a null String if the input is a blank string.
func (s *String) UnmarshalText(text []byte) error {
s.String = string(text)
s.Valid = s.String != ""
return nil
}
// SetValid changes this String's value and also sets it to be non-null.
func (s *String) SetValid(v string) {
s.String = v
s.Valid = true
}
// Ptr returns a pointer to this String's value, or a nil pointer if this String is null.
func (s String) Ptr() *string {
if !s.Valid {
return nil
}
return &s.String
}
// IsZero returns true for null strings, for potential future omitempty support.
func (s String) IsZero() bool {
return !s.Valid
}