Weird issue in Form - php

Question

I am working in a simple form of html with php. I am adding some fields including file upload.
But I am facing a weird issue. When I upload image and submit form. It submits but when I do not upload image and submit the form. It says "Unsupported file format"
I checked that when I do not upload file and submit the form. It does not even post the form. Only "Unsupported file format" line come to the page and whole page blank.
This is my code:
<form action="" method="post" enctype="multipart/form-data">
<table class="form-table">
<tr>
<th>Title<font color="#ff0000">*</font></th>
<td><input name="title" type="text" value="<?=$_POST['title']?>" size="40" /></td>
</tr>
<tr>
<th>Image<font color="#ff0000">*</font></th>
<td><input type="file" name="file_name" /></td>
</tr>
<tr>
<th> </th>
<td> Dimensions: <?=$imgwidth?> x <?=$imgheight?> (Max: 2MB) <br />
JPG format is the one recommended.</td>
</tr>
<tr>
<th></th>
<td><input type="submit" name="btnAdd_cat" class="button" value="Add" /></td>
</tr>
</table>
</form>
Php code:
<?php
if(isset($_POST['btnAdd_cat'])){
$error = "";
$title = addslashes($_POST['title']);
if(empty($title)) $error .= "Please enter title.<br/>";
if(empty($error)){
$sql = "INSERT INTO ".CATEGORIES." (`title`, `status`) VALUES ('$title', '1')";
mysql_query($sql) or die(__LINE__.mysql_error());
$id = $insert_id = mysql_insert_id();
$success = "Successfuly added.<br/>";
$filename = $_FILES['file_name']['name'];
if(!empty($filename)){
$imgext = strtolower(substr($filename, -4));
$img = ereg_replace("[^a-z0-9._]", "",str_replace(" ", "-",str_replace("%20", "-", strtolower($title))));
$filename = "category-".$insert_id."-".$img.$imgext;
$savefile = "../pictures/".$filename;
//upload
if(copy($_FILES['file_name']['tmp_name'], $savefile)){
//echo "....Image uploaded ";
}else{$warning = "Failed to upload image!<br/>";}
chmod("$savefile",0777);
if(resize_picture("$savefile","$savefile","$imgwidth","$imgheight")){
//echo "....Image resized ";
}else{$warning = "Failed to resize image!<br/>";}
$image = $filename;
}
if(mysql_query("UPDATE ".CATEGORIES." SET image='".$image."' WHERE id='".$id."'")){
$success .= "Image added.<br/>";
unset($_GET);
} else {die(__LINE__.mysql_error());}
}
}
?>
This page comes when I submit without uploading file:
http://prntscr.com/706ght
Please help me in this.
Thanks

Answer 1

Put the file upload code block in if(isset($_FILES['file_name'])){} i.e. check whether the file is posted or not. because as you have said that the error occurred when you are not selecting any file so it better to check whether the file is posted before running the uploading code.
Hope this will help in solving your problem.

Answer 2

As you have said that when you don't select any file it's showing you an error then you need to update your if condition from
$filename = $_FILES['file_name']['name'];
if(!empty($filename))
to
$filename = $_FILES['file_name']['error'];
if($filename != 4) // Check no file is uploaded
There is a section in php documentation about file handling. You will find that you can check various errors and from file-upload-errors
UPLOAD_ERR_OK
Value: 0; There is no error, the file uploaded with success.
<...>
UPLOAD_ERR_NO_FILE
Value: 4; No file was uploaded.

Answer 3

I created a real instance of your code, suppressing what depends on your context (such as SQL-related, and so on): despite you have a number of points that should be enhanced (see below):
it never fired the error you mentioned
more interesting: POST was always done, while you report it was not the case for you
From this latter point I infer the issue should come from some control executed by your browser. So can you give more details about that: which browser are you using, with which plugins and under which OS?
Besides that, there are some points that don't matter for the issue you have pointed out, but should be more strictly coded:
as already mentioned, rather than using if(!empty(filename)), processing the uploaded file should be conditioned to something like if($_FILES['file_name']['error'] == UPLOAD_ERR_OK) before anything else
an important point is that ereg_replace() is deprecated as of PHP 5.3.0: you should use preg_replace() instead
when preparing to save title into database, use mysql_escape_string() rather than addslashes() (or turn using PDO, which takes care of that for you: look at http://php.net/manual/en/ref.pdo-mysql.php)
more generally, about your database processing, you had better to save data in a unique step when your image has been already processed; this way you optimize performance (with only one DB access), while you avoid getting incomplete records containing titles for which no image reference was finally registered