英文:
What's the idiomatic way to work with dates without time in golang?
问题
我正在使用Go编写一个REST API,处理的日期不代表一个具体的时间点。
JSON数据以“2006-01-02”格式在服务器和客户端之间传输,该数据与使用DATE列的mysql数据库进行交互。
我尝试的一种方法是创建一个嵌入了Time的结构体,并实现JSON和SQL转换接口的实现,以便能够正确地与端点交互,同时仍然可以使用Time方法进行日期计算和格式化。例如:
package localdate
import (
"time"
"encoding/json"
"database/sql/driver"
)
type LocalDate struct {
time.Time
}
func NewLocalDate(year int, month time.Month, day int) LocalDate {
time := time.Date(year, month, day, 0, 0, 0, 0, time.UTC)
return LocalDate{Time: time}
}
const LocalDateFormat = "2006-01-02" // yyyy-mm-dd
func (ld *LocalDate) UnmarshalJSON(data []byte) error {
// 解析并设置ld.Time变量
}
func (ld *LocalDate) MarshalJSON() ([]byte, error) {
return json.Marshal(ld.Format(LocalDateFormat))
}
// sql.Scanner implementation to convert a time.Time column to a LocalDate
func (ld *LocalDate) Scan(value interface{}) error {}
// sql/driver.Valuer implementation to go from LocalDate -> time.Time
func (ld *LocalDate) Value() (driver.Value, error) {}
// 用于将LocalDate转换为可以插入查询的内容
// 我们可以直接使用ld.Time,但这将发送“2015-01-01 00:00:00 +0000 UTC”
// 而不是DATE查询参数的“2015-01-01”。(这对于mysql有效,但官方上是无效的SQL)
func (ld *LocalDate) SqlDate() string {
return ld.Format(LocalDateFormat)
}
然后其他结构体可以使用这种类型,并且在我的问题领域中可以实现日期类型的90%功能。
上述代码可以工作,但我觉得我在与Go的潮流作斗争。所以对于这门语言的老手,我有几个问题:
你认为这段代码会带来更多的痛苦吗?
如果是这样,你会推荐使用哪种风格?
英文:
I'm writing a REST API in Go, working with dates that don't represent a single point in time.
It's JSON data going to and from the server in "2006-01-02" format, with that data talking to a mysql database using DATE columns.
One thing I've tried is to create a struct that embeds a Time, and implements JSON and SQL conversion interface implementations to be able to correctly interact with the endpoints while still having Time methods available for date math and formatting. e.g.:
package localdate
import (
"time"
"encoding/json"
"database/sql/driver"
)
type LocalDate struct {
time.Time
}
func NewLocalDate(year int, month time.Month, day int) LocalDate {
time := time.Date(year, month, day, 0, 0, 0, 0, time.UTC)
return LocalDate{Time: time}
}
const LocalDateFormat = "2006-01-02" // yyyy-mm-dd
func (ld *LocalDate) UnmarshalJSON(data []byte) error {
// parse and set the ld.Time variable
}
func (ld *LocalDate) MarshalJSON() ([]byte, error) {
return json.Marshal(ld.Format(LocalDateFormat))
}
// sql.Scanner implementation to convert a time.Time column to a LocalDate
func (ld *LocalDate) Scan(value interface{}) error {}
// sql/driver.Valuer implementation to go from LocalDate -> time.Time
func (ld *LocalDate) Value() (driver.Value, error) {}
// used to convert a LocalDate into something we can plug into a query
// we could just use ld.Time, but that would send '2015-01-01 00:00:00 +0000 UTC'
// instead of '2015-01-01' for the DATE query parameter. (Which works for mysql, but is officially invalid SQL)
func (ld *LocalDate) SqlDate() string {
return ld.Format(LocalDateFormat)
}
And then other structs can be of this type, and get 90% there to representing the date type in my problem domain.
The above code works, but I feel like I'm fighting against the Go current. So a couple questions for the veterans of the language:
Do you think this code will cause more pain than it'll save?
If so, what style would you recommend?
答案1
得分: 11
我使用来自cloud.google.com/go/civil包的civil.Date
。
英文:
I use civil.Date
from the package cloud.google.com/go/civil
答案2
得分: 3
我认为你可以将数据存储为time.Time
类型,但为了JSON的目的,将其转换为字符串:
type LocalDate struct {
t time.Time `json:",string"` // 甚至可以在这里匿名工作
}
关于如何在SQL中使用这个方法,请参考:https://github.com/go-sql-driver/mysql#timetime-support
英文:
I think you can store your data as time.Time
but convert it to a string for JSON purposes:
type LocalDate struct {
t time.Time `json:",string"` // might even work anonymously here
}
To see how to make this work with SQL: https://github.com/go-sql-driver/mysql#timetime-support
答案3
得分: 0
如果项目使用Gorm,我们可以自由地使用gorm.io/datatypes
中的datatypes.Date
。
import "gorm.io/datatypes"
type UserWithDate struct {
gorm.Model
Name string
Date datatypes.Date
}
user := UserWithDate{Name: "jinzhu", Date: datatypes.Date(time.Now())}
DB.Create(&user)
// INSERT INTO `user_with_dates` (`name`,`date`) VALUES ("jinzhu","2020-07-17 00:00:00")
DB.First(&result, "name = ? AND date = ?", "jinzhu", datatypes.Date(curTime))
// SELECT * FROM user_with_dates WHERE name = "jinzhu" AND date = "2020-07-17 00:00:00" ORDER BY `user_with_dates`.`id` LIMIT 1
来源:github.com/go-gorm/datatypes#date
在底层,它仍然是time.Time
,但时间部分的值为零。
我使用的示例:
// 将日期时间的时间部分设为零
date, err := datatypes.Date(time.Now()).Value()
if err != nil {
return err
}
dateValue := date.(time.Time)
英文:
If the project uses Gorm then we can freely use datatypes.Date
from gorm.io/datatypes
import "gorm.io/datatypes"
type UserWithDate struct {
gorm.Model
Name string
Date datatypes.Date
}
user := UserWithDate{Name: "jinzhu", Date: datatypes.Date(time.Now())}
DB.Create(&user)
// INSERT INTO `user_with_dates` (`name`,`date`) VALUES ("jinzhu","2020-07-17 00:00:00")
DB.First(&result, "name = ? AND date = ?", "jinzhu", datatypes.Date(curTime))
// SELECT * FROM user_with_dates WHERE name = "jinzhu" AND date = "2020-07-17 00:00:00" ORDER BY `user_with_dates`.`id` LIMIT 1
Source: github.com/go-gorm/datatypes#date
Under the hood, it's still time.Time
, but with zeroed values of the time part.
Example of my usage:
// make the time part of datetime equal to zero
date, err := datatypes.Date(time.Now()).Value()
if err != nil {
return err
}
dateValue := date.(time.Time)
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