Go text/template Form handling, with custom FuncMap – function returning blank string outputs garbage

huangapple
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英文:

Go text/template Form handling, with custom FuncMap - function returning blank string outputs garbage

问题

使用Go的html/template功能，结合自定义的FuncMap。我定义的自定义函数"isChecked(checkName string, form url.Values)"会在表单中存在名为checkName的复选框时返回字符串"checked"，否则返回空字符串。它的功能正常，但有个奇怪的问题是，在未选中的复选框的完成HTML中，我看到了字符串"ZgotmplZ"，而实际上应该没有任何字符串。以下是设置FuncMap的main.go程序：

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"html/template"
  6. 	"log"
  7. 	"net/http"
  8. 	"net/url"
  9. )
  11. var tpl *template.Template
  13. func init() {
  14. 	tpl = template.Must(template.New("").Funcs(fm).ParseFiles("templates/check-box.html"))
  15. }
  17. var fm = template.FuncMap{
  18. 	"isChecked": isChecked,
  19. }
  21. func isChecked(checkName string, form url.Values) string {
  22. 	if form.Has(checkName) {
  23. 		return "checked"
  24. 	}
  25. 	return ""
  26. }
  28. func checkboxHandler(w http.ResponseWriter, r *http.Request) {
  29. 	err := r.ParseForm()
  30. 	if err != nil {
  31. 		log.Fatalln(err)
  32. 	}
  34. 	err = tpl.ExecuteTemplate(w, "check-box.html", r.Form)
  35. 	if err != nil {
  36. 		log.Fatalln(err)
  37. 	}
  38. }
  40. func main() {
  41. 	http.HandleFunc("/checkbox/", checkboxHandler)
  43. 	err := http.ListenAndServe(":8080", nil)
  44. }

以下是模板：

  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <meta http-equiv="X-UA-Compatible" content="IE=edge">
  6.     <meta name="viewport" content="width=device-width, initial-scale=1.0">
  7.     <title>Checkbox Control</title>
  8. </head>
  9. <body>
  11.     <h1>Go html/template Form Handling - Checkbox</h1>
  13.     <div>
  14.     Form Data: {{.}}
  15.     </div>
  17.     <form action="/checkbox/" method="POST">
  19.         <div>
  20.             <label for="checkbox">Check Box</label>
  21.             <input type="checkbox" name="check1" id="checkbox" value="check1" {{isChecked "check1" .}}>Check 1
  22.             <input type="checkbox" name="check2" id="checkbox" value="check2" {{isChecked "check2" .}}>Check 2
  23.             <input type="checkbox" name="check3" id="checkbox" value="check3" {{isChecked "check3" .}}>Check 3
  24.         </div>
  26.         <div>
  27.             <button type="submit">Submit</button>
  28.         </div>
  30.     </form>
  32. </body>
  33. </html>

提交表单并选中复选框的结果是正确的。但是当我查看源代码时，对于未选中的复选框，我得到了一个奇怪的字符串"ZgotmplZ"（换句话说，似乎FuncMap中的自定义函数没有为未选中的复选框返回空字符串）：

  1.         <div>
  2.             <label for="checkbox">Check Box</label>
  3.             <input type="checkbox" name="check1" id="checkbox" value="check1" checked>Check 1
  4.             <input type="checkbox" name="check2" id="checkbox" value="check2" ZgotmplZ>Check 2
  5.             <input type="checkbox" name="check3" id="checkbox" value="check3" ZgotmplZ>Check 3
  6.         </div>

同时，我想知道是否有其他建议可以将复选框的"checked"状态传递给HTML模板。

谢谢！

英文:

Using Go html/template functionality, with custom FuncMap. The custom function I've defined "isChecked(checkName string, form url.Values)" returns the string "checked" if the checkbox with checkName exists in the form, and a blank string if it does not. It works fine, but the curious thing is on the completed HTML for an un-checked checkbox, I am seeing the string "ZgotmplZ" where there should be no string at all. Here is the main.go program that sets up the FuncMap:

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;html/template&quot;
  6. 	&quot;log&quot;
  7. 	&quot;net/http&quot;
  8. 	&quot;net/url&quot;
  9. )
  11. var tpl *template.Template
  13. func init() {
  14. 	tpl = template.Must(template.New(&quot;&quot;).Funcs(fm).ParseFiles(&quot;templates/check-box.html&quot;))
  15. }
  17. var fm = template.FuncMap{
  18. 	&quot;isChecked&quot;: isChecked,
  19. }
  21. func isChecked(checkName string, form url.Values) string {
  22. 	if form.Has(checkName) {
  23. 		return &quot;checked&quot;
  24. 	}
  25. 	return &quot;&quot;
  26. }
  28. func checkboxHandler(w http.ResponseWriter, r *http.Request) {
  29. 	err := r.ParseForm()
  30. 	if err != nil {
  31. 		log.Fatalln(err)
  32. 	}
  34. 	err = tpl.ExecuteTemplate(w, &quot;check-box.html&quot;, r.Form)
  35. 	if err != nil {
  36. 		log.Fatalln(err)
  37. 	}
  38. }
  40. func main() {
  41. 	http.HandleFunc(&quot;/checkbox/&quot;, checkboxHandler)
  43. 	err := http.ListenAndServe(&quot;:8080&quot;, nil)
  44. }

Here is the template:

  1. &lt;!DOCTYPE html&gt;
  2. &lt;html lang=&quot;en&quot;&gt;
  3. &lt;head&gt;
  4.     &lt;meta charset=&quot;UTF-8&quot;&gt;
  5.     &lt;meta http-equiv=&quot;X-UA-Compatible&quot; content=&quot;IE=edge&quot;&gt;
  6.     &lt;meta name=&quot;viewport&quot; content=&quot;width=device-width, initial-scale=1.0&quot;&gt;
  7.     &lt;title&gt;Checkbox Control&lt;/title&gt;
  8. &lt;/head&gt;
  9. &lt;body&gt;
  11.     &lt;h1&gt;Go html/template Form Handling - Checkbox&lt;/h1&gt;
  13.     &lt;div&gt;
  14.     Form Data: {{.}}
  15.     &lt;/div&gt;
  17.     &lt;form action=&quot;/checkbox/&quot; method=&quot;POST&quot;&gt;
  19.         &lt;div&gt;
  20.             &lt;label for=&quot;checkbox&quot;&gt;Check Box&lt;/label&gt;
  21.             &lt;input type=&quot;checkbox&quot; name=&quot;check1&quot; id=&quot;checkbox&quot; value=&quot;check1&quot; {{isChecked &quot;check1&quot; .}}&gt;Check 1
  22.             &lt;input type=&quot;checkbox&quot; name=&quot;check2&quot; id=&quot;checkbox&quot; value=&quot;check2&quot; {{isChecked &quot;check2&quot; .}}&gt;Check 2
  23.             &lt;input type=&quot;checkbox&quot; name=&quot;check3&quot; id=&quot;checkbox&quot; value=&quot;check3&quot; {{isChecked &quot;check3&quot; .}}&gt;Check 3
  24.         &lt;/div&gt;
  26.         &lt;div&gt;
  27.             &lt;button type=&quot;submit&quot;&gt;Submit&lt;/button&gt;
  28.         &lt;/div&gt;
  30.     &lt;/form&gt;
  32. &lt;/body&gt;
  33. &lt;/html&gt;

The result of submitting the form and checking the checkboxes is good. But when I examine source, I get this funny string "ZgotmplZ" for checkboxes that are not checked (in other words, it seems the custom function in the FuncMap is not returning a blank string for un-checked checkboxes):

  1.         &lt;div&gt;
  2.             &lt;label for=&quot;checkbox&quot;&gt;Check Box&lt;/label&gt;
  3.             &lt;input type=&quot;checkbox&quot; name=&quot;check1&quot; id=&quot;checkbox&quot; value=&quot;check1&quot; checked&gt;Check 1
  4.             &lt;input type=&quot;checkbox&quot; name=&quot;check2&quot; id=&quot;checkbox&quot; value=&quot;check2&quot; ZgotmplZ&gt;Check 2
  5.             &lt;input type=&quot;checkbox&quot; name=&quot;check3&quot; id=&quot;checkbox&quot; value=&quot;check3&quot; ZgotmplZ&gt;Check 3
  6.         &lt;/div&gt;

Also wondering if anyone has other suggestions on how to propate checkbox "checked" states to an html template.

Thanks!

答案1

得分: 0

模板发出ZgotmplZ，因为它不喜欢在属性上下文中出现空字符串。通过以下方式进行修复。

从isChecked函数返回bool类型：

  1. func isChecked(checkName string, form url.Values) bool {
  2.     return form.Has(checkName) 
  3. }

在模板中使用if语句：

  1. {{if isChecked "check1" .}}checked{{end}}
英文:

The template emits ZgotmplZ because it does not like an empty string in an attribute context. Fix by doing the following.

Return bool from isChecked:

  1. func isChecked(checkName string, form url.Values) bool {
  2.      return form.Has(checkName) 
  3. }

Use an if action in the template:

  1. {{if isChecked &quot;check1&quot; .}}checked{{end}}

huangapple
  • 本文由 发表于 2022年10月23日 04:09:43
  • 转载请务必保留本文链接：https://go.coder-hub.com/74166762.html
  • forms
  • go
  • go-templates
  • texttemplate
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