在Go模板中使用Random Int来生成一个随机数。

huangapple
go评论111阅读模式
英文:

Use Random Int for a Photo in Go Template

问题

我在代码中有一个简单的随机整数，我将其传递给模板。

  1. min := 1
  2. max := 1563
  3. Photo := rand.Intn(max - min + 1)
  4. fmt.Println(Photo)
  6. tmpl.ExecuteTemplate(w, "index.html", struct {
  7.     Pages        []Page
  8.     CurrentPage  int
  9.     TotalPage    int
  10.     NextPage     int
  11.     PreviousPage int
  12.     LastPage     int
  13.     ShowNext     bool
  14.     ShowPrevious bool
  15.     Photo        int
  16. }{
  17.     Pages:        pages,
  18.     CurrentPage:  pageIndex + 1,
  19.     TotalPage:    totalPaginationPage,
  20.     NextPage:     pageIndex + 1,
  21.     PreviousPage: pageIndex - 1,
  22.     LastPage:     totalPaginationPage - 1,
  23.     ShowNext:     pageIndex+1 < totalPaginationPage,
  24.     ShowPrevious: pageIndex-1 >= 0,
  25.     Photo:        Photo,
  26. })

我的想法是随机选择一张照片（文件夹中有1563张），然后在模板中使用。

  1. {{range .Pages}}
  2.     <div id="content">
  3.       <div class="card">
  4.         <p>
  5.           <div class="card-img">
  6.             <a href="{{.Slug}}">    
  7.                 <img src="{{.Photo}}" alt=""/>
  8.             </a>
  9.           </div>
  10.           <div class="card-info">
  11.             <div class="card-info-title">
  12.                 <a href="{{.Slug}}">{{.Title}}</a>
  13.             </div>
  14.             ...
  15.           </div>
  16.         </p>
  17.       </div>
  18.     </div>
  19. {{end}}

src="{{.Photo}}" 导致模板崩溃，好像变量没有正确传递。也许问题在于这是在循环内部，所以我需要为每篇文章生成一个随机数以显示一张照片？

有没有其他方法可以直接在模板中完成？

更新

根据指导，我现在有以下代码：

  1. min := 1
  2. max := 1563
  3. Photos := make([]int, len(pages))
  4. for i := range Photos {
  5.     Photos[i] = rand.Intn(max - min + 1)
  6. }
  8. tmpl.ExecuteTemplate(w, "index.html", struct {
  9.     Pages        []Page
  10.     CurrentPage  int
  11.     TotalPage    int
  12.     NextPage     int
  13.     PreviousPage int
  14.     LastPage     int
  15.     ShowNext     bool
  16.     ShowPrevious bool
  17.     Photo        []int
  18. }{
  19.     Pages:        pages,
  20.     CurrentPage:  pageIndex + 1,
  21.     TotalPage:    totalPaginationPage,
  22.     NextPage:     pageIndex + 1,
  23.     PreviousPage: pageIndex - 1,
  24.     LastPage:     totalPaginationPage - 1,
  25.     ShowNext:     pageIndex+1 < totalPaginationPage,
  26.     ShowPrevious: pageIndex-1 >= 0,
  27.     Photo:        Photos,    
  28. })

在模板中：

  1. {{range $idx, $page := .Pages}}
  2.     <div id="content">
  3.       <div class="card">
  4.         <p>
  5.           <div class="card-img">
  6.             <a href="{{.Slug}}">    
  7.                 <img src="{{index $.Photos $idx}}" alt=""/>
  8.             </a>
  9.           </div>
  10.           <div class="card-info">
  11.             <div class="card-info-title">
  12.                 <a href="{{.Slug}}">{{.Title}}</a>
  13.             </div>
  14.             ...
  15.           </div>
  16.         </p>
  17.       </div>
  18.     </div>
  19. {{end}}

我还尝试了以下代码：

  1. <a href="{{.Slug}}">
  2.     <img src="/public/suisse/suisse{{index $.Photos $idx}}.jpg" alt=""/>
  3. </a>

但不幸的是，模板在调用 {{index $.Photos $idx}} 后停止执行。我猜这可能是我这边的一个拼写错误？

英文:

I have a simple random integer in my code that I am passing to the template

  1.             min := 1
  2. 			max := 1563
  3. 			Photo := rand.Intn(max - min + 1)
  4. 			fmt.Println(Photo)
  6. 			tmpl.ExecuteTemplate(w, &quot;index.html&quot;, struct {
  7. 				Pages        []Page
  8. 				CurrentPage  int
  9. 				TotalPage    int
  10. 				NextPage     int
  11. 				PreviousPage int
  12. 				LastPage     int
  13. 				ShowNext     bool
  14. 				ShowPrevious bool
  15. 				Photo        int
  16. 			}{
  18. 				Pages:        pages,
  19. 				CurrentPage:  pageIndex + 1,
  20. 				TotalPage:    totalPaginationPage,
  21. 				NextPage:     pageIndex + 1,
  22. 				PreviousPage: pageIndex - 1,
  23. 				LastPage:     totalPaginationPage - 1,
  24. 				ShowNext:     pageIndex+1 &lt; totalPaginationPage,
  25. 				ShowPrevious: pageIndex-1 &gt;= 0,
  26. 				Photo:        Photo,
  27. 			})

the idea is to randomize a photo (I have 1563 in the folder) so in my template

{{range .Pages}}

  1. &lt;div id=&quot;content&quot;&gt;
  2.   &lt;div class=&quot;card&quot;&gt;
  3.     &lt;p&gt;
  4.       &lt;div class=&quot;card-img&quot;&gt;
  6.   
  7.     
  8.         &lt;a href=&quot;{{.Slug}} &quot;&gt;    &lt;img
  9.         
  11.         src=&quot;{{.Photo}}&quot;
  12.         alt=&quot;&quot;
  13.       /&gt;&lt;/a&gt;
  14.         &lt;/div&gt;
  15.         
  16.         &lt;div class=&quot;card-info&quot;&gt;
  17.           &lt;div class=&quot;card-info-title&quot;&gt;
  18. &lt;a href=&quot;{{.Slug}} &quot; &gt;{{.Title}} &lt;/a&gt;
  19. &lt;/div&gt;

src="{{.Photo}}" crashes the template, is like if the variable is not properly passed. Perhaps the issue is that this is inside a loop so I need a random number per each article in order to display a photo ?

Is there any other way to do it directly in the template ?

Update

Thanks to the guidance I now have

  1. min := 1
  2. max := 1563
  3. Photos := make([]int, len(pages))
  4. for i := range Photos {
  5.     Photos[i] = rand.Intn(max - min + 1)
  6. }
  7. 			
  9. 			tmpl.ExecuteTemplate(w, &quot;index.html&quot;, struct {
  10. 				Pages        []Page
  11. 				CurrentPage  int
  12. 				TotalPage    int
  13. 				NextPage     int
  14. 				PreviousPage int
  15. 				LastPage     int
  16. 				ShowNext     bool
  17. 				ShowPrevious bool
  18. 				Photo        []int
  19. 			}{
  21. 				Pages:        pages,
  22. 				CurrentPage:  pageIndex + 1,
  23. 				TotalPage:    totalPaginationPage,
  24. 				NextPage:     pageIndex + 1,
  25. 				PreviousPage: pageIndex - 1,
  26. 				LastPage:     totalPaginationPage - 1,
  27. 				ShowNext:     pageIndex+1 &lt; totalPaginationPage,
  28. 				ShowPrevious: pageIndex-1 &gt;= 0,
  29. 				Photo:        Photos,	
  30. 			})

and in the template

  1. {{range $idx, $page := .Pages}}
  4. &lt;div id=&quot;content&quot;&gt;
  5.   &lt;div class=&quot;card&quot;&gt;
  6.     &lt;p&gt;
  7.       &lt;div class=&quot;card-img&quot;&gt;
  9.   
  10.     
  11.         &lt;a href=&quot;{{.Slug}} &quot;&gt;    &lt;img
  12.         
  13.  src=&quot;{{index $.Photos $idx}}&quot;
  14.                alt=&quot;&quot;
  15.       /&gt;&lt;/a&gt;
  16.         &lt;/div&gt;
  17.         
  18.         &lt;div class=&quot;card-info&quot;&gt;
  19.           &lt;div class=&quot;card-info-title&quot;&gt;
  20. &lt;a href=&quot;{{.Slug}} &quot; &gt;{{.Title}} &lt;/a&gt;
  21. &lt;/div&gt;
  23. &lt;div class=&quot;card-info-category&quot;&gt;
  24.   &lt;p&gt;
  26. tags:
  27. &lt;/p&gt;
  28.        
  29.           &lt;ul&gt;
  30.        
  31.             &lt;li&gt;
  32.   {{.Tags}}
  33.           &lt;/li&gt;
  34.   
  36. &lt;/ul&gt;
  37. &lt;/div&gt;
  40. &lt;div class=&quot;card-info-date&quot;&gt;
  41. {{.Date}} 
  43. &lt;/div&gt;
  45. &lt;/div&gt;
  46. &lt;/p&gt;
  47. &lt;/div&gt;
  49. &lt;/div&gt;
  53.        
  54. {{end}}

also tried

  1.       &lt;a href=&quot;{{.Slug}} &quot;&gt;    &lt;img
  2.         
  3.  src=&quot;/public/suisse/suisse{{index $.Photos $idx}}.jpg&quot;
  4.                alt=&quot;&quot;
  5.       /&gt;&lt;/a&gt;

but unfortunately the templates stop executing as soon as I call

  1. {{index $.Photos $idx}}

I assume it is a typo of some sort from my side?

答案1

得分: 1

{{range}}操作会改变点（.），所以在{{range .Pages}}内部的{{.Photo}}将会解析为.Pages中的元素。

使用$来引用模板执行时传递的“外部”原始值：

  1. src="{{$.Photo}}"

尽管这只是一个整数，但你可能想在路径或URL中使用它，类似于这样：

  1. src="/path/to/images?id={{$.Photo}}"

注意：如果你想为所有页面使用不同的图片，你需要为每个页面传递一个不同的数字，而不仅仅是一个。然后在页面中添加一个Photo字段，然后你可以在{{range}}内部使用{{.Photo}}，就像你原来的代码中那样。

你写道你不能修改Page，因为它来自你的数据库。如果是这样，那么可以传递一个随机数的切片，并使用index来访问它们，就像这样：

  1. min := 1
  2. max := 1563
  3. Photos := make([]int, len(pages))
  4. for i := range Photos {
  5.     Photos[i] = rand.Intn(max - min + 1)
  6. }
  8. tmpl.ExecuteTemplate(w, "index.html", struct {
  9.     Pages        []Page
  10.     CurrentPage  int
  11.     TotalPage    int
  12.     NextPage     int
  13.     PreviousPage int
  14.     LastPage     int
  15.     ShowNext     bool
  16.     ShowPrevious bool
  17.     Photo        []int
  18. }{
  20.     Pages:        pages,
  21.     CurrentPage:  pageIndex + 1,
  22.     TotalPage:    totalPaginationPage,
  23.     NextPage:     pageIndex + 1,
  24.     PreviousPage: pageIndex - 1,
  25.     LastPage:     totalPaginationPage - 1,
  26.     ShowNext:     pageIndex+1 < totalPaginationPage,
  27.     ShowPrevious: pageIndex-1 >= 0,
  28.     Photo:        Photos,
  29. })

在模板中：

  1. {{range $idx, $page := .Pages}}
  2.     <a href="{{.Slug}}"><img
  3.         src="{{index $.Photos $idx}}"
  4.         alt=""/>
  5.     </a>
  6. {{end}}

或者注册一个random函数，你可以在模板中调用它：

  1. // 像之前一样解析模板，但是首先注册一个random函数：
  2. min, max := 1, 1563
  3. tmpl, err := template.New("").Funcs(template.FuncMap{
  4.     "random": func() int { return rand.Intn(max - min + 1) },
  5. }).ParseFiles("template-name.html")

然后你可以在模板中这样调用它：

  1. {{range .Pages}}
  2.     <a href="{{.Slug}}"><img
  3.         src="{{random}}"
  4.         alt=""/>
  5.     </a>
  6. {{end}}
英文:

The {{range}} action changes the dot, so {{.Photo}} inside the {{range .Pages}} will be resolved on the elements of .Pages.

Use $ to refer to the "outer", original value passed to the template execution:

  1. src=&quot;{{$.Photo}}&quot;

Although this is only an integer, you likely want to use it in a path or an URL, something like this:

  1. src=&quot;/path/to/images?id={{$.Photo}}&quot;

Note: If you want a different image for all pages, you have to pass a different number for each, not just a single one. Then add a Photo field to page, and then you can refer to it inside the {{range}} as {{.Photo}} as in your original code.

You wrote you can't modify Page as it comes from your database. If so, then either pass a slice of random numbers and access them with index like this:

  1. min := 1
  2. max := 1563
  3. Photos := make([]int, len(pages))
  4. for i := range Photos {
  5.     Photos[i] = rand.Intn(max - min + 1)
  6. }
  8. tmpl.ExecuteTemplate(w, &quot;index.html&quot;, struct {
  9.     Pages        []Page
  10.     CurrentPage  int
  11.     TotalPage    int
  12.     NextPage     int
  13.     PreviousPage int
  14.     LastPage     int
  15.     ShowNext     bool
  16.     ShowPrevious bool
  17.     Photo        []int
  18. }{
  20.     Pages:        pages,
  21.     CurrentPage:  pageIndex + 1,
  22.     TotalPage:    totalPaginationPage,
  23.     NextPage:     pageIndex + 1,
  24.     PreviousPage: pageIndex - 1,
  25.     LastPage:     totalPaginationPage - 1,
  26.     ShowNext:     pageIndex+1 &lt; totalPaginationPage,
  27.     ShowPrevious: pageIndex-1 &gt;= 0,
  28.     Photo:        Photos,
  29. })

In template:

  1. {{range $idx, $page := .Pages}}
  2.     &lt;a href=&quot;{{.Slug}} &quot;&gt;&lt;img
  3.         src=&quot;{{index $.Photos $idx}}&quot;
  4.         alt=&quot;&quot;/&gt;
  5.     &lt;/a&gt;
  6. {{end}}

Or register a random function which you can call from the template:

  1. // Parse the template as you did, but first register a random function:
  2. min, max := 1, 1563
  3. tmpl, err := template.New(&quot;&quot;).Funcs(template.FuncMap{
  4.     &quot;random&quot;: func() int { return rand.Intn(max - min + 1) },
  5. }).ParseFiles(&quot;template-name.html&quot;)

And you can call it from the template like this:

  1. {{range .Pages}}
  2.     &lt;a href=&quot;{{.Slug}} &quot;&gt;&lt;img
  3.         src=&quot;{{random}}&quot;
  4.         alt=&quot;&quot;/&gt;
  5.     &lt;/a&gt;
  6. {{end}}

huangapple
  • 本文由 发表于 2022年11月28日 02:38:42
  • 转载请务必保留本文链接：https://go.coder-hub.com/74592772.html
  • go
  • go-templates
  • random
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