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

huangapple
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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：

  1. package localdate
  3. import (
  4.     "time"
  5.     "encoding/json"
  6.     "database/sql/driver"
  7. )
  9. type LocalDate struct {
  10.     time.Time
  11. }
  13. func NewLocalDate(year int, month time.Month, day int) LocalDate {
  14.     time := time.Date(year, month, day, 0, 0, 0, 0, time.UTC)
  15.     return LocalDate{Time: time}
  16. }
  18. const LocalDateFormat = "2006-01-02" // yyyy-mm-dd
  20. func (ld *LocalDate) UnmarshalJSON(data []byte) error {
  21.     // 解析并设置ld.Time变量
  22. }
  24. func (ld *LocalDate) MarshalJSON() ([]byte, error) {
  25.     return json.Marshal(ld.Format(LocalDateFormat))
  26. }
  28. // sql.Scanner implementation to convert a time.Time column to a LocalDate
  29. func (ld *LocalDate) Scan(value interface{}) error {}
  31. // sql/driver.Valuer implementation to go from LocalDate -> time.Time
  32. func (ld *LocalDate) Value() (driver.Value, error)  {}
  34. // 用于将LocalDate转换为可以插入查询的内容
  35. // 我们可以直接使用ld.Time，但这将发送“2015-01-01 00:00:00 +0000 UTC”
  36. // 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）
  37. func (ld *LocalDate) SqlDate() string  {
  38.     return ld.Format(LocalDateFormat)
  39. }

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.:

  1. package localdate
  3. import (
  4.     "time"
  5.     "encoding/json"
  6.     "database/sql/driver"
  7. )
  9. type LocalDate struct {
  10.     time.Time
  11. }
  13. func NewLocalDate(year int, month time.Month, day int) LocalDate {
  14.     time := time.Date(year, month, day, 0, 0, 0, 0, time.UTC)
  15.     return LocalDate{Time: time}
  16. }
  18. const LocalDateFormat = "2006-01-02" // yyyy-mm-dd
  20. func (ld *LocalDate) UnmarshalJSON(data []byte) error {
  21.     // parse and set the ld.Time variable
  22. }
  24. func (ld *LocalDate) MarshalJSON() ([]byte, error) {
  25.     return json.Marshal(ld.Format(LocalDateFormat))
  26. }
  28. // sql.Scanner implementation to convert a time.Time column to a LocalDate
  29. func (ld *LocalDate) Scan(value interface{}) error {}
  31. // sql/driver.Valuer implementation to go from LocalDate -> time.Time
  32. func (ld *LocalDate) Value() (driver.Value, error)  {}
  34. // used to convert a LocalDate into something we can plug into a query
  35. // we could just use ld.Time, but that would send '2015-01-01 00:00:00 +0000 UTC'
  36. // instead of '2015-01-01' for the DATE query parameter.  (Which works for mysql, but is officially invalid SQL)
  37. func (ld *LocalDate) SqlDate() string  {
  38.     return ld.Format(LocalDateFormat)
  39. }

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：

  1. type LocalDate struct {
  2.   t time.Time `json:",string"` // 甚至可以在这里匿名工作
  3. }

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:

  1. type LocalDate struct {
  2.   t time.Time `json:",string"` // might even work anonymously here
  3. }

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。

  1. import "gorm.io/datatypes"
  3. type UserWithDate struct {
  4.     gorm.Model
  5.     Name string
  6.     Date datatypes.Date
  7. }
  9. user := UserWithDate{Name: "jinzhu", Date: datatypes.Date(time.Now())}
  10. DB.Create(&user)
  11. // INSERT INTO `user_with_dates` (`name`,`date`) VALUES ("jinzhu","2020-07-17 00:00:00")
  13. DB.First(&result, "name = ? AND date = ?", "jinzhu", datatypes.Date(curTime))
  14. // 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：

  1. // 将日期时间的时间部分设为零
  2. date, err := datatypes.Date(time.Now()).Value()
  3. if err != nil {
  4.     return err
  5. }
  7. dateValue := date.(time.Time)
英文:

If the project uses Gorm then we can freely use datatypes.Date from gorm.io/datatypes

  1. import "gorm.io/datatypes"
  3. type UserWithDate struct {
  4. 	gorm.Model
  5. 	Name string
  6. 	Date datatypes.Date
  7. }
  9. user := UserWithDate{Name: "jinzhu", Date: datatypes.Date(time.Now())}
  10. DB.Create(&user)
  11. // INSERT INTO `user_with_dates` (`name`,`date`) VALUES ("jinzhu","2020-07-17 00:00:00")
  13. DB.First(&result, "name = ? AND date = ?", "jinzhu", datatypes.Date(curTime))
  14. // 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:

  1. // make the time part of datetime equal to zero
  2. date, err := datatypes.Date(time.Now()).Value()
  3. if err != nil {
  4. 	return err
  5. }
  7. dateValue := date.(time.Time)

huangapple
  • 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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