What's the idiomatic way to work with dates without time in golang?

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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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  • 本文由 发表于 2015年2月11日 12:49:11
  • 转载请务必保留本文链接:https://go.coder-hub.com/28446796.html
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