英文:
What is the cause of this panic?
问题
我对Go语言还比较新手，能有人帮我诊断一下这个问题吗？
type ValidationStatus struct {
Passed bool
Errors map[string]*ValidationError
}
// ...
status := ValidationStatus{Passed: true}
// ...
status.Passed = false
fmt.Println(reflect.TypeOf(typeField.Name)) // string
fmt.Println(reflect.TypeOf(validationError)) // *validation.ValidationError
status.Errors[typeField.Name] = validationError // 这里引发了恐慌。
validationError 在 validation 包中定义。这段代码与结构体位于同一个文件中。
这是我第一次遇到这样的问题，我觉得可能是我错误地使用了 map，但我不明白为什么这不会导致编译错误，所以可能是类型问题？如果有解决这个问题的指导意见，我将非常感激。
英文:
I am fairly new to Go, could someone help me diagnose this problem.
type ValidationStatus struct {
Passed bool
Errors map[string]*ValidationError
}
// ...
status := ValidationStatus{Passed: true}
// ...
status.Passed = false
fmt.Println(reflect.TypeOf(typeField.Name)) // string
fmt.Println(reflect.TypeOf(validationError)) // *validation.ValidationError
status.Errors[typeField.Name] = validationError // Panic triggered here.
validationError is defined in the validation package. This code is in the same file as the struct.
This is the first time I have hit an issue like this, I think I may be using the map incorrectly but then I don't understand why this wouldn't cause a compile error so maybe a type issue? Any pointers to solve this would be much appreciated.
答案1
得分: 5
你没有告诉我们错误信息是什么！
使用内置函数make创建一个新的空映射值，该函数接受映射类型和可选的容量提示作为参数：
make(map[string]int) make(map[string]int, 100)
例如，
status := ValidationStatus{Passed: true, Errors: make(map[string]*ValidationError)}
英文:
You didn't tell us what the error message was!
> Map types
>
> A new, empty map value is made using the built-in function make, which
> takes the map type and an optional capacity hint as arguments:
>
> make(map[string]int)
> make(map[string]int, 100)
For example,
status := ValidationStatus{Passed: true, Errors: make(map[string]*ValidationError)}
答案2
得分: 3
你的地图是nil。你只需要初始化它。这就是为什么大多数对象初始化都隐藏在一个函数后面：
status := ValidationStatus{Passed: true, Errors: make(map[string]*ValidationError)}
或者，隐藏在一个函数后面：
status := NewValidationStatus()
// ...
func NewValidationStatus() ValidationStatus {
return ValidationStatus{
Passed: true,
Errors: make(map[string]*ValidationError),
}
}
英文:
Your map is nil. You simply need to initialize it. This is why most object initialization is hidden behind a function:
status := ValidationStatus{Passed: true, Errors: make(map[string]*ValidationError)}
..or, behind a function:
status := NewValidationStatus()
// ...
func NewValidationStatus() ValidationStatus {
return ValidationStatus{
Passed: true,
Errors: make(map[string]*ValidationError),
}
}
<kbd>See it on the playground</kbd>
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