h：inputFile的值在其他输入验证失败后变为空白，如何保留其值？ [英] h:inputFile value becomes blank after validation fail of other input, how to retain its value?

问题描述

对于许多其他标准的JSF组件，当表单被提交并且服务器端验证失败时，页面被再次呈现，其中先前提交的表单域被填充以供用户编辑并重新提交。我正在从新的h：inputFile寻找相同的行为，我没有找到它。

作为一个简单的例子，我有一个形式与h：inputText和一个h：inputFile。 inputText启用了服务器端验证。如果用户输入无效文本并选择文件并提交，则文件将被上传，表单将在文本字段中显示为无效文本，并显示一个表示验证结果的h：消息。我试图解决的问题是在这一点上，他们纠正他们的文字输入，但不得不再次选择一个文件，并再次上传。有什么基本的我想念，或者这是预期的行为？ HTML不允许预先填充< input type =file> ，否则会打开一个巨大的安全漏洞。由于JSF在这个上下文中只是一个HTML代码生成器，所以它不能做太多的事情。

最好的办法是将ajax提交表单和ajax呈现只有真正需要更新的部分，如消息（即不要使用 render =@ form）。例如

 < / p> h：form enctype =multipart / form-data> 
< h：inputText id =text/> 
< h：message id =m_textfor =text/> 
 
 < h：message id =m_filefor =file/> 
 
< h：commandButton value =submit> 
 < / h：commandButton> 
< / h：表格> 
  

With many other standard JSF components, when a form is submitted and server side validation fails, the page is rendered again with the previously submitted form fields filled in for the user to edit and resubmit. I am looking for that same behavior from the new h:inputFile and I'm not finding it.

As a simple example, I have a form with an h:inputText and an h:inputFile. The inputText has server side validation enabled. If the user enters invalid text and selects a file and submits, the file is uploaded and the form is rendered with the invalid text in the text field and a h:message indicating the validation result. The issue I'm trying to address is at this point they correct their text input, but have to select a file again, and upload it again. Is there something basic I am missing, or is this the intended behavior?

解决方案

HTML disallows prefilling an <input type="file"> as that otherwise opens a huge security hole. As JSF is in this context just a HTML code generator, it can't do much against that.

Your best bet is to ajax-submit the form and ajax-render only the parts which really need to be updated, such as messages (i.e. don't use render="@form"). This way the initial input value stays.

E.g.

<h:form enctype="multipart/form-data">
    <h:inputText id="text" />
    <h:message id="m_text" for="text" />

    <h:inputFile id="file" />
    <h:message id="m_file" for="file" />

    <h:commandButton value="submit">
        <f:ajax execute="@form" render="m_text m_file" />
    </h:commandButton>
</h:form>

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