Question

我正在使用Python和CGI开发Web应用程序。对于表单验证，我打算使用JavaScript。这是场景 - 有一个文本框，用户在其中输入项目名称并单击提交按钮。如果文本框中没有输入任何内容并发出警报，我想抓住。

对于JavaScript函数，我使用了参数，project_form（用于表单）和project_name用于文本框。但我不清楚的是在哪里放这个功能。截至目前，我正试图将其放在表单标签中。但它没有用。我不知何故认为我必须将project_form和project_name参数传递给函数，并且由于代码结构，我不可能将函数放在'head'部分。我在这里粘贴我的代码。谢谢你的帮助。

<form action="create_project.py" method="POST" name="project_form">
  <input type="text" name="project_name" size="40" onclick="javascript:document.project_form.submit.disabled=false"
  id="acpro_inp0">
  <br>
  <script type="text/javascript">
    function ValidateTextbox(project_form, project_name) {
      var tb_value = project_form.project_name.value;
      if (tb_value == null || tb_value.trim() == "") {
        alert("Please enter something");
        project_form.project_name.focus();
        return false;
      }
      return true;
    }
  </script>
  return ValidateTextbox('project_form','project_name')
  <p>
  </p>
  <input type="submit" name="submit" value="Submit" onsubmit="return ValidateTextbox('project_form','project_name')"
  disabled="">
</form>

以下是相关的Python代码 -

import yate
import jshelper

print yate.start_response()
print yate.include_header("Create a new project.")
#Section to create a new project
print yate.start_form("create_project.py","project_form")
print yate.text_box("project_name",form_name="project_form")
jshelper.JSTextBoxValidate("project_form","project_name")
print yate.end_form("Submit",is_disabled = 'True', onsubmit_callback = "return ValidateTextbox('project_form','project_name')")
print yate.include_footer(({"Home": "../index.html"}))

这是另一段Python代码，我尝试动态创建JS函数。

def JSTextBoxValidate(form_name,tb_name):
    print '<script type="text/javascript">'
    print 'function ValidateTextbox' + '(' + form_name + ',' + tb_name + ')'
    print '{' 
    print 'var tb_value = ' + form_name + '.' + tb_name + '.' + 'value;' 
    print 'if (tb_value==null || tb_value.trim()=="")'
    print '{' 
    print 'alert("Please enter something");'
    print form_name + '.' + tb_name + '.' + 'focus();' 
    print 'return false;'
    print '}' 
    print 'return true;'
    print '}'
    print '</script>'

不知怎的，我感觉我可能在这个过程中没有走上正轨，必须有更好的方法。所以我会感谢帮助我让这件事情发挥作用。注 - 包yate来自Head First Python，我正在使用并扩展该代码中的模板。我在我的项目文档中添加了类似的注释。这是我的个人项目。

Answer 1

以其应有的方式重写HTML代码：

<script type="text/javascript">
  function ValidateTextbox(input) { //we take an object representation of the HTML <input> tag (not just a string)
    if (input.value.trim() == "") { //the attribute value is already defined in the tag now, so it couldn't be null
      alert("Please enter something");
      input.focus(); //move the cursor to the incriminated input
      return false; //preventing from submitting the form (assuming the function is called as a return value)
    }
    return true; //allowing the form to be submitted (assuming the function is called as a return value)
  }
  //function added a you seemed to need something like that
  function DisableFormSubmit(theForm, e) { //we take the form object as argument, and e may be the event object given from the keypress event
    var submitButton=theForm.submit; //to ease typing this code, the submit button is assigned to a local variable
    if(theForm.project_name.value.trim()=='') { //if we have no value for the project_name input of the form
      submitButton.disabled=true; //we disable the submit button
      submitButton.value="Submit - enter a name first"; //and we give a hint why it is disabled in the text printed on the button
    } else { //in this case project_name has a valid value
      submitButton.disabled=false; //the submit button is enabled
      submitButton.value="Submit"; //we remove the hint we gave
    }
    //processing the event now, to know what to return (key 13 is Enter, returning false on it will prevent the form from being submitted by pressing Enter)
    if(window.event) //MSIE compatibility
      return window.event.keyCode!=13;
    else if(e) //web browser's behavior
      return e.which!=13;
    }
  }
</script>
<form action="create_project.py" method="POST" name="project_form" onsubmit="return ValidateTextBox(this.project_name);">
  <input type="text" name="project_name" value="" size="40" onkeypress="return DisableFormSubmit(this.form, event);" id="acpro_inp0">
  <br>

  <input type="submit" name="submit" value="">
</form>
<script type='text/javascript'>
  DisableFormSubmit(document.forms['project_form']); //we call this function once after the <form> has loaded so that we init the submit button with a standard way
</script>

对于Python代码，我无法分辨，因为我不知道这种语言，但您不需要“动态”创建JS函数来对表单的有效性进行客户端检查。注意客户端的事情，意思是不安全，这意味着如果您在该字段中绝对需要一个值，那么请在服务器端进行第二次检查（显然使用Python）。你的问题是：

您尝试使用<script></script>标记
你提供字符串作为参数，而你实际上需要HTML标签的对象表示：而不是给'project_form'和'project_name' - 注意引号 - 你需要像document.project_form或{{1并且附加了document.forms['project_form']之前的其中一个。请注意这里没有引号。
您在.project_name中使用了属性onsubmit，而其位置应位于<input>中（尽管此点可能不是错误的原因）

希望这会有所帮助;）

JavaScript表单验证 - 使用Python和CGI检查空文本框

1 个答案: