简单的if语句不起作用,请使用模板。

huangapple go评论71阅读模式
英文:

Simple if not working go template

问题

所以我正在对来自结构体的布尔值进行简单的if检查,但似乎不起作用,它只是停止渲染HTML。

以下是结构体的示例:

type Category struct {
    ImageURL      string
    Title         string
    Description   string
    isOrientRight bool
}

现在我有一个该Category结构体的切片,我使用range来显示它们。

以下是一个结构体的示例:

juiceCategory := Category{
    ImageURL:      "lemon.png",
    Title:         "Juices and Mixes",
    Description:   `Explore our wide assortment of juices and mixes expected by
                    today's lemonade stand clientelle. Now featuring a full line of
                    organic juices that are guaranteed to be obtained from trees that
                    have never been treated with pesticides or artificial
                    fertilizers.`,
    isOrientRight: true,
}

我尝试了多种方式,比如下面的方式,但它们都没有起作用:

{{range .Categories}}
    {{if .isOrientRight}}
        Hello
    {{end}}
    {{if eq .isOrientRight true}}
        Hello
    {{end}}
    
    <!-- 不打印任何内容 -->
    {{ printf .isOrientRight }} 
    
{{end}}
英文:

So I am doing a simple if check on a bool from a struct but it doesn't seem to work, it just stop rendering the HTML.

So the following struct is like this:

type Category struct {
	ImageURL      string
	Title         string
	Description   string
	isOrientRight bool
}

Now I have a slice of that Category struct which I get to display with a range.

Bellow is an example of one struct:

juiceCategory := Category{
	ImageURL: &quot;lemon.png&quot;,
	Title:    &quot;Juices and Mixes&quot;,
	Description: `Explore our wide assortment of juices and mixes expected by
						today&#39;s lemonade stand clientelle. Now featuring a full line of
						organic juices that are guaranteed to be obtained from trees that
						have never been treated with pesticides or artificial
						fertilizers.`,
	isOrientRight: true,
}

I've tried multiple ways, like below, but none of them worked:

{{range .Categories}}
	{{if .isOrientRight}}
       Hello
	{{end}}
	{{if eq .isOrientRight true}}
       Hello
	{{end}}
   
   &lt;!-- Print nothing --&gt;
   {{ printf .isOrientRight }} 

{{end}}

答案1

得分: 8

你必须导出你想要从模板中访问的所有字段:将其首字母改为大写的 I

type Category struct {
    ImageURL      string
    Title         string
    Description   string
    IsOrientRight bool
}

以及对它的每个引用:

{{range .Categories}}
    {{if .IsOrientRight}}
       Hello
    {{end}}
    {{if eq .IsOrientRight true}}
       Hello
    {{end}}

   <!-- 不打印任何内容 -->
   {{ printf .IsOrientRight }} 

{{end}}

每个未导出的字段只能从声明它的包中访问。你的包声明了 Category 类型,而 text/templatehtml/template 是不同的包,所以如果你希望这些包能够访问它,你需要将其导出。

Template.Execute() 返回一个错误,如果你存储/检查了它的返回值,你会立即发现这个问题,因为你会得到一个类似于以下错误的消息:

template: :2:9: executing "" at .isOrientRight: isOrientRight is an unexported field of struct type main.Category

Go Playground 上可以看到你代码的一个可运行示例。

英文:

You have to export all the fields you want to access from templates: change its first letter to capital I:

type Category struct {
    ImageURL      string
    Title         string
    Description   string
    IsOrientRight bool
}

And every reference to it:

{{range .Categories}}
    {{if .IsOrientRight}}
       Hello
    {{end}}
    {{if eq .IsOrientRight true}}
       Hello
    {{end}}

   &lt;!-- Print nothing --&gt;
   {{ printf .IsOrientRight }} 

{{end}}

Every unexported field can only be accessed from the declaring package. Your package declares the Category type, and text/template and html/template are different packages, so you need to export it if you want those packages to have access to it.

Template.Execute() returns an error, should you have stored / examined its return value, you would have found this out immediately, as you'd get an error similar to this one:

> template: :2:9: executing "" at <.isOrientRight>: isOrientRight is an unexported field of struct type main.Category

See a working example of your code on the Go Playground.

答案2

得分: 2

如果生活给你带来了一些带有小写变量名的模板,可能是从用于其他事情的Pug模板源构建而成的,那么有一种方法可以解决这个问题...

你可以使用map[string]interface{}来保存要传递给模板的值,所以在上面的例子中:

juiceCategory := map[string]interface{}{
    "ImageURL":     "lemon.png",
    "Title":        "果汁和混合饮料",
    "Description":  `探索我们广泛的果汁和混合饮料,满足今天柠檬水摊的客户需求。现在推出一整套有机果汁,保证从未经过杀虫剂或人工肥料处理的树木中获得。`,
    "isOrientRight": true,
}

现在就不需要修改你的模板了...

英文:

If life inflicts templates on you which for some reason have lower-case variable names - perhaps constructed from a Pug template source that is also used for other things - there is a way around this issue...

You can use a map[string]interface{} to hold the values to be passed into the template, so in the example above:

juiceCategory := map[string]interface{}{
    &quot;ImageURL&quot;: &quot;lemon.png&quot;,
    &quot;Title&quot;:    &quot;Juices and Mixes&quot;,
    &quot;Description&quot;: `Explore our wide assortment of juices and mixes expected by
                        today&#39;s lemonade stand clientelle. Now featuring a full line of
                        organic juices that are guaranteed to be obtained from trees that
                        have never been treated with pesticides or artificial
                        fertilizers.`,
    &quot;isOrientRight&quot;: true,
}

and now there is no need to change your template...

huangapple
  • 本文由 发表于 2016年11月9日 03:21:02
  • 转载请务必保留本文链接:https://go.coder-hub.com/40494828.html
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