PHP检查是否选择了要上传的文件 [英] PHP check if there is a file selected for upload

问题描述

我有此表格，我想检查用户是否选择了文件.

I have this form and I would like to check if the user has selected a file or not.

<form action="upload.php" method="POST" enctype="multipart/form-data" >
    <select name="category">
        <option value="cat1" name="cat1">Productfotografie</option>
        <option value="cat2" name="cat2">Portretten</option>
        <option value="cat3" name="cat3">Achitectuur</option>
    </select>
    <input type="file" name="file_upload">
    <input type="submit" name="submit" value="Upload photo">
</form>

我编写了此PHP代码以对其进行测试

I wrote this PHP code to test it

if (empty($_POST) === false) {
    $fileupload = $_POST['file_upload'];
    if (empty($fileupload) === true) { //
            echo "Error no file selected";     
    } else {
        print_r($_FILES);
    }
} 

但是，即使我选择了某些内容，也会出现错误，未选择文件".有什么线索吗?对不起，我真的是PHP新手.

But I get the "Error no file selected" even if I DO select something. Any clue? I'm sorry I'm really new in PHP.

编辑:我已经尝试替换了$fileupload = $_FILES['file_upload']，但它会显示一个空错误

I already tried replacing $fileupload = $_FILES['file_upload'] but it prints an empty error

(Array([file_upload] => Array([name] => [type] => [tmp_name] => [错误] => 4 [大小] => 0))))

(Array ( [file_upload] => Array ( [name] => [type] => [tmp_name] => [error] => 4 [size] => 0 ) ))

当我不输入文件时?

推荐答案

使用$_FILES数组和UPLOAD_ERR_NO_FILE常量:

if(!isset($_FILES['file_upload']) || $_FILES['file_upload']['error'] == UPLOAD_ERR_NO_FILE) {
    echo "Error no file selected"; 
} else {
    print_r($_FILES);
}

您还可以检查UPLOAD_ERR_OK，该文件表示文件是否已成功上传(存在且没有错误).

You can also check UPLOAD_ERR_OK which indicates if the file was successfully uploaded (present and no errors).

注意:您不能在$_FILES['file_upoad']数组上使用empty()，因为即使没有文件上传，该数组仍将被填充并且设置了error元素，这意味着empty()将返回false

Note: you cannot use empty() on the $_FILES['file_upoad'] array, because even if no file is uploaded, the array is still populated and the error element is set, which means empty() will return false.

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