gotosocial/internal/api/model/nullable.go
Vyr Cossont 6a8af42647
[bugfix] Allow unsetting filter expiration dates (#3560)
* Regression tests for #3497 (v1 and v2)
* use Nullable type for v2 form.expires_in

---------

Co-authored-by: tobi <tobi.smethurst@protonmail.com>
2024-11-26 08:23:00 -08:00

107 lines
2.8 KiB
Go

// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package model
import (
"bytes"
"encoding/json"
"errors"
)
// Nullable is a generic type, which implements a field that can be one of three states:
//
// - field is not set in the request
// - field is explicitly set to `null` in the request
// - field is explicitly set to a valid value in the request
//
// Nullable is intended to be used with JSON unmarshalling.
//
// Adapted from https://github.com/oapi-codegen/nullable/blob/main/nullable.go
type Nullable[T any] struct {
state nullableState
value T
}
type nullableState uint8
const (
nullableStateUnspecified nullableState = 0
nullableStateNull nullableState = 1
nullableStateSet nullableState = 2
)
// Get retrieves the underlying value, if present,
// and returns an error if the value was not present.
func (t Nullable[T]) Get() (T, error) {
var empty T
if t.IsNull() {
return empty, errors.New("value is null")
}
if !t.IsSpecified() {
return empty, errors.New("value is not specified")
}
return t.value, nil
}
// IsNull indicates whether the field
// was sent, and had a value of `null`
func (t Nullable[T]) IsNull() bool {
return t.state == nullableStateNull
}
// IsSpecified indicates whether the field
// was sent either as a value or as `null`.
func (t Nullable[T]) IsSpecified() bool {
return t.state != nullableStateUnspecified
}
// If field is unspecified,
// UnmarshalJSON won't be called.
func (t *Nullable[T]) UnmarshalJSON(data []byte) error {
// If field is specified as `null`.
if bytes.Equal(data, []byte("null")) {
t.setNull()
return nil
}
// Otherwise, we have an
// actual value, so parse it.
var v T
if err := json.Unmarshal(data, &v); err != nil {
return err
}
t.set(v)
return nil
}
// setNull indicates that the field
// was sent, and had a value of `null`
func (t *Nullable[T]) setNull() {
*t = Nullable[T]{state: nullableStateNull}
}
// set the underlying value to given value.
func (t *Nullable[T]) set(value T) {
*t = Nullable[T]{
state: nullableStateSet,
value: value,
}
}