我有HTML表单，并希望发送文件myfile的'使用Ajax和jQuery：

I have html form and want send file 'myfile' with Ajax and jQuery:

<form method="post" enctype="multipart/form-data">
    <input type="file" name="myfile" id="myfile">
</form>

我的JavaScript code：

My javascript code:

function getFile(fieldName){
    var itemValue = $('input[name="' + fieldName + '"]')[0].files[0];
    return itemValue;
}

function sendFile(){
    var formaData = new FormData();
    var itemName = 'myfile';
    var itemValue = getFile(itemName);
    formaData.append(itemName, itemValue);
    $.ajax({
        type: 'POST',
        data: formaData,
        processData: false,
        contentType: false,
    });
}

一切工作正常，当文件被choosen。我在服务器$ _FILES全局数组，并在其中的数据通过Ajax其中有：

All works fine when file is choosen. I have in the server $_FILES global array and data in it which got via Ajax:

["myfile"]=>
    array(5) {
        ["name"]=>
        string(13) "file_name.jpg"
        ["type"]=>
        string(10) "image/jpeg"
        ["tmp_name"]=>
        string(14) "/tmp/phpefJlk3"
        ["error"]=>
        int(0)
        ["size"]=>
        int(344100)
    }

当文件不choosen的问题！ 当我不选择任何文件和发送Ajax请求，然后我有空$ _FILES，但我有$ _ POST与现场MYFILE'等于'不确定'。但我需要在$ _FILES'myfile的'场均是空的。我想是这样的：

The problem when file is not choosen! When I don't choose any file and send Ajax request then I have empty $_FILES, but I have $_POST with field 'myfile' equals 'undefined'. But I need 'myfile' field in $_FILES even it is empty. I want something like:

["myfile"]=>
    array(5) {
        ["name"]=>
        string(0) ""
        ["type"]=>
        string(0) ""
        ["tmp_name"]=>
        string(0) ""
        ["error"]=>
        int(4)
        ["size"]=>
        int(0)
    }

以上是我在$ _FILES globall数组，如果我把空的形式没有Ajax。我想的一样，如果我使用Ajax。难道posssible？

Above is what I have in $_FILES globall array if I send empty form without Ajax. I want the same if I using Ajax. Is it posssible?

推荐答案

处理文件，AJAX并非如此简单。它配备了大量的因不同的客户端，休文件和所有的东西的问题。你的情况（因为你可以在你的简单误差=这里看到的），没有文件被选中，所以没有必要发送有关不给定文件的信息。不产生费用。也许你看看到控制器。如果数据是不同的（AJAXPOST或POST）以便创建两个PHP-操作。一个AJAX的处理程序和一个后处理程序。在这种情况下，可以处理不同的后DATAS。

Handling files with AJAX is not that simple. It comes up with a lot of problems due to different clients, hugh files and all that stuff. (As you can see in your "simple"-Error here =) In your case, no file is selected so there is no need to send information about "no given file". Dont produce overheads. Maybe you take a look into your controller. If the data is that different (AJAXPOST or POST) so create two PHP-Actions. One AJAX handler and one POST handler. In that case you can handle the different post-datas.

此信息将帮助您： How我可以上传文件异步？

您需要使用像 Uploadify 或的 Valums ，使这项工作。刚刚看了一点关于AJAX和Filepost。

You need to use Plugins like Uploadify, or Valums to make that work. Just read a bit more about AJAX and Filepost.