在用户选择文件之前,如何禁用提交按钮?
我的页面上有一个表单:
<table>
<form method="post" enctype="multipart/form-data" id="messageupload">
<@spring.bind "messageUploadCommand.*"/>
<tr>
<td><@spring.formInput 'messageUploadCommand.multipartFile' '' 'file' /></td>
<td><button type="submit" id="searchButton">Upload</button></td>
<td><@spring.formSingleSelect
'messageUploadCommand.messageFormat',
messageFormats, '' />
<@spring.showErrors '<br>', 'error' /> </td>
</tr>
</form>
</table>
如果用户在选择文件之前提交表单我
freemarker.template.TemplateException: Error executing macro: formSingleSelect required parameter: options is not specified.
at freemarker.core.Macro$Context.sanityCheck(Macro.java:211)
at freemarker.core.Macro$Context.runMacro(Macro.java:169)
at freemarker.core.Environment.visit(Environment.java:603)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:106)
at freemarker.core.Environment.visit(Environment.java:210)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:210)
at freemarker.core.Environment.process(Environment.java:190)
at freemarker.template.Template.process(Template.java:237)
at ...
答案 0 :(得分:0)
我就这样做了:
<table>
<form method="post" enctype="multipart/form-data" id="messageupload">
<@spring.bind "messageUploadCommand.*"/>
<tr>
<#assign onChangeScript = "document.getElementById('uploadButton').disabled = (value.length=0); ">
<td><@spring.formInput 'messageUploadCommand.multipartFile' 'onchange=\"${onChangeScript}\"' 'file' /></td>
<td><button type="submit" disabled="true"
id="searchButton">Upload</button></td>
<td><@spring.formSingleSelect
'messageUploadCommand.messageFormat',
messageFormats, '' />
<@spring.showErrors '<br>', 'error' /> </td>
</tr>
</form>
</table>
我通过Freemarker变量添加了文件选择器onchange脚本,默认情况下禁用了该按钮。 onchange脚本测试值的长度,即文件名,为零。