Question

I’m trying to send form fields and file to a web service using php curl. The form has already been passed from a browser to a proxy php client web app and I’m trying to forward it to the web service.

When I pass an array to curl_setopt like this:

curl_setopt($this->ch, CURLOPT_POSTFIELDS, $this->fields);

I get a Array to String notice although it is meant to take an array. Here’s my array that is passed to $this->fields in the constructor.

$fields = array('title'=>$title,
'content'=>$content,
'category'=>$category,
'attachment'=>$_FILES['attachment']);

If I pass a string using http_build_query my web serivce complains about not having multipart/form data.

If I then force the multipart/form enctype using curl_setopt I get an error saying there’s no boundary:

org.apache.commons.fileupload.FileUploadException: the request was rejected because no multipart boundary was found

Any ideas?

Answer 1

The array to string notice you have with the following code :

$fields = array(
  'title'=>$title,
  'content'=>$content,
  'category'=>$category,
  'attachment'=>$_FILES['attachment']
);
curl_setopt($this->ch, CURLOPT_POSTFIELDS, $fields);

is not because of you’re passing an array as 3rd parameter to curl_setopt : it’s because you’re passing an array for attachment.

If you want to pass a file this way, you should pass its absolute path, pre-pending a `@` before it :

$fields = array(
  'title'=>$title,
  'content'=>$content,
  'category'=>$category,
  'attachment'=> '@' . $_FILES['attachment']
);
curl_setopt($this->ch, CURLOPT_POSTFIELDS, $fields);

(This is supposing that $_FILES['attachment'] contains the full path to your file — up to you to change this code so it’s using the right data, if needed)

As a reference, quoting the manual page of [**`curl_setopt`**][1], for the `CURLOPT_POSTFIELDS` option :

The full data to post in a HTTP "POST" operation.

To post a file, prepend a filename with @ and use the full path.

This can either be passed as a urlencoded string like 'para1=val1&para2=val2&...' or as an array with the field name as key and field data as value.

If value is an array, the Content-Type header will be set to multipart/form-data.