英文:
Handling Dynamic Errors In Go (Specifically database/sql Package)
问题
在Go语言中使用database/sql
包执行sql.Exec
等操作时,可能会返回动态生成且未引用的错误,例如:
"Error 1062: Duplicate entry '192' for key 'id'"
问题在于,同一次调用sql.Exec
可能还会返回其他错误,例如:
"Error 1146: Table 'tbl' doesn't exist"
在不使用字符串比较或错误代码的模式匹配的情况下,如何区分这两种错误?或者说,这些方法是否是解决这个问题的惯用解决方案?
英文:
Using the database/sql
package in go for things like sql.Exec
will return dynamically generated, unreferenced errors such as
"Error 1062: Duplicate entry '192' for key 'id'"
The problem is that it can also return errors such as
"Error 1146: Table 'tbl' doesn't exist"
From the same call to sql.Exec
How can I tell the difference between these two errors without
- String comparison, or
- Pattern matching for error code
Or are those idiomatic viable solutions for this problem?
答案1
得分: 15
database/sql包无法解决这个问题,它是特定于驱动程序的。例如,对于mysql,你可以使用以下代码:
if mysqlError, ok := err.(*mysql.MySQLError); ok {
if mysqlError.Number == 1146 {
//处理
}
}
此外,你还可以找到一些错误常量包,比如来自VividCortex的mysqlerr,并使用它:
if mysqlError, ok := err.(*mysql.MySQLError); ok {
if mysqlError.Number == mysqlerr.ER_NO_SUCH_TABLE {
//处理
}
}
这并不比模式匹配更好,但似乎更符合惯用方式。
英文:
database/sql package does not solve this problem. It's driver specific. For example, for mysql you can use:
if mysqlError, ok := err.(*mysql.MySQLError); ok {
if mysqlError.Number == 1146 {
//handling
}
}
Also, you can find some error constant package, like mysqlerr from VividCortex, and use it:
if mysqlError, ok := err.(*mysql.MySQLError); ok {
if mysqlError.Number == mysqlerr.ER_NO_SUCH_TABLE {
//handling
}
}
It's not much better than pattern matching, but seems to be more idiomatic.
答案2
得分: 0
我认为没有惯用的解决方案,但我编写了一个简单的函数来获取错误编号,这样你就可以轻松地进行比较。
在这个解决方案中,我假设错误消息的构造始终相同:"Error -某个数字-:错误描述"。
如果错误中没有数字或者出现了问题,它会返回0。
func ErrorCode(e error) int {
err := e.Error() //错误的描述
if len(err) < 6 { //如果太短,返回0
return 0
}
i := 6 //跳过"Error "部分
for ; len(err) > i && unicode.IsDigit(rune(err[i])); i++ {
} //将i递增,直到达到err的末尾或者错误代码的末尾
n, e := strconv.Atoi(string(err[6:i])) //将其转换为整数
if e != nil {
return 0 //出现了问题
}
return n //返回错误代码
}
Go playground链接:http://play.golang.org/p/xqhVycsuyI
英文:
I think there's no idiomatic solution, but I wrote a simple function for getting the error number, so you can easily compare them.
In this solution I assume that the construction of the error message is always the same: "Error -some number here-: Error description".
If there's no number in the error or something went wrong it returns 0.
func ErrorCode(e error) int {
err := e.Error() //the description of the error
if len(err) < 6 { //if its too small return 0
return 0
}
i := 6 //Skip the part "Error "
for ; len(err) > i && unicode.IsDigit(rune(err[i])); i++ {
} // Raising i until we reach the end of err or we reach the end of error code
n, e := strconv.Atoi(string(err[6:i])) //convert it to int
if e != nil {
return 0 //something went wrong
}
return n //return the error code
}
Go playground link: http://play.golang.org/p/xqhVycsuyI
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