我怎么知道我的输入类型是否为"file"?选择了内容 [英] How I know if my input type="file" has content selected

问题描述

我有一个简单的输入文件<input type="file" name="file" id="file"> 但是我想在发布后验证输入文件是否包含内容.

i have a simple input file <input type="file" name="file" id="file"> but I'm trying to validate after the post if the input file has content.

我尝试使用$("#file").val()，但是控件的dom总是一样.

I trying with $("#file").val() but, the dom of the controls is the same always.

推荐答案

您的意思是:帖子后，您的意思是:

What do you mean by: after the post, do you mean:

-点击提交按钮之后但要发布还是提交?

-After clicking on a submit button but before posting or submitting?

-或者您是说，在提交内容之后，内容已经到达服务器了?

-Or you mean after it has been submitted and the content has reached the server?

如果是第一种情况，请确保将false返回到表单，以便它不提交，并且您可以进行验证，例如:

If it is the first case, make sure to return false to the form so it doesn't submit, and you can validate, for example:

<form onsubmit="return false">

或在提交后调用验证函数后尝试将布尔值返回表单:

or try to return a boolean to the form after calling a validation function on submit:

<form onsubmit="return validate()">

然后使用Jquery验证您的数据:

Then using Jquery validate your data:

function validate(){

  valid = true;

     if($("#file").val() == ''){
         // your validation error action
        valid = false;

     }

    return valid //true or false
}

如果发现错误，则返回false，如果数据有效，则返回true. 在了解了它的工作原理之后，最终，所有这些都可以通过Jquery完成:

if you find errors return false, if the data is valid return true. After understanding how it works, ultimately, all of this can be done with Jquery:

HTML:

<form id="fileform" action="nextpage.php">

JS:

$('#fileform').submit(function(){
     valid = true;

     if($("#file").val() == ''){
        // your error validation action
        valid =  false;
    }

    return valid
});

此外，如果您要查看正在提交的文件类型，则可以查看以下帖子:

Also, if you are checking to see what type of file is being submitted, you can check this post: jQuery - INPUT type=File , Image FileType Validation options?

如果您要做的是之后验证提交的数据，则必须使用服务器脚本语言(如PHP)来编写验证代码.

If what you want to do is validate the data AFTER submitting then you have to code the validation in a server scripting language like PHP.

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