英文:
Go Template if value is set and is false
问题
我正在使用 Listmonk，它使用 Go Templates。我遇到了这样一种情况：用户状态的变量（.Subscriber.Attribs.Pro）可能存在（如果存在，则为 true 或 false）。我只想在该值存在时显示一段文本。
我已经有了一段代码，如果 Pro 属性被设置了，它可以正常工作。然而，如果没有设置，它会被处理为 not ''，导致值为 true。
{{ if not .Subscriber.Attribs.Pro }}
You are not a Pro user!
{{ end }}
请问如何让这段代码仅在 Pro 属性明确设置为 false 时运行？
英文:
I am using Listmonk which utilizes Go Templates. I have a situation where a variable for user status (.Subscriber.Attribs.Pro) may exist (and if it does, it is true or false. I want to display a block of text only if the value exists.
The code I have works if the Pro attribute is set. However if it is not set, it will be processed as not '' which leads to a value of true.
{{ if not .Subscriber.Attribs.Pro }}
You are not a Pro user!
{{ end }}
How do I have this code run only if the Pro attribute is explicitly set to false
答案1
得分: 2
所以基本上，你只想在提供了.Subscriber.Attribs.Pro并且其值为false时显示文本。可以进行如下比较：
{{ if eq false .Subscriber.Attribs.Pro }}
You are not a Pro user!
{{ end }}
我们可以进行如下测试：
t := template.Must(template.New("").Parse("{{ if eq false .Pro }}You are not a Pro user!\n{{ end }}"))
fmt.Println("Doesn't exist:")
if err := t.Execute(os.Stdout, nil); err != nil {
panic(err)
}
fmt.Println("Pro is false:")
m := map[string]interface{}{
"Pro": false,
}
if err := t.Execute(os.Stdout, m); err != nil {
panic(err)
}
fmt.Println("Pro is true:")
m["Pro"] = true
if err := t.Execute(os.Stdout, m); err != nil {
panic(err)
}
输出结果将会是（可以在Go Playground上尝试）：
Doesn't exist:
Pro is false:
You are not a Pro user!
Pro is true:
正如你所见，只有当Pro被明确设置为false时，{{if}}块的内容才会被执行。
英文:
So basically you only want to display the text if .Subscriber.Attribs.Pro is supplied and is false. So do a comparison:
{{ if eq false .Subscriber.Attribs.Pro }}
You are not a Pro user!
{{ end }}
We can test it like:
t := template.Must(template.New("").Parse("{{ if eq false .Pro }}You are not a Pro user!\n{{ end }}"))
fmt.Println("Doesn't exist:")
if err := t.Execute(os.Stdout, nil); err != nil {
panic(err)
}
fmt.Println("Pro is false:")
m := map[string]interface{}{
"Pro": false,
}
if err := t.Execute(os.Stdout, m); err != nil {
panic(err)
}
fmt.Println("Pro is true:")
m["Pro"] = true
if err := t.Execute(os.Stdout, m); err != nil {
panic(err)
}
Output will be (try it on the Go Playground):
Doesn't exist:
Pro is false:
You are not a Pro user!
Pro is true:
As you can see, the body of the {{if}} block is only executed when Pro is explicitly set to false.
答案2
得分: 1
使用包含的Sprig的hasKey函数：
{{if hasKey .Subscriber.Attribs "Pro"}}
{{ if not .Subscriber.Attribs.Pro }}
你不是专业用户！
{{ end }}
{{ end }}
英文:
Use the included Sprig hasKey function:
{{if hasKey .Subscriber.Attribs "Pro"}}
{{ if not .Subscriber.Attribs.Pro }}
You are not a Pro user!
{{ end }}
{{ end }}
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