Executing Curl with PHP

curl, docverter, latex, markdown, php

Solution

I solved my own problem. There were two main problems with the above code:

1) The `$fields` array was incorrectly formatted for the `input_files[]`. It needed a `@/` and mime-type declaration (see code below)

2) The `curl_exec()` output (the actual newly created file contents) needed to be returned and not just `true/false` which is this function's default behavior. This is accomplished by setting the curl option `curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);` (see code below).

Full working example

//set POST variables
$url = 'http://c.docverter.com/convert';
$fields = array('from' => 'markdown',
    'to' => 'pdf',
    'input_files[]' => "@/".realpath('markdown.md').";type=text/x-markdown; charset=UTF-8"
    );

//open connection
$ch = curl_init();

//set options 
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-type: multipart/form-data"));
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POSTFIELDS, $fields); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); //needed so that the $result=curl_exec() output is the file and isn't just true/false

//execute post
$result = curl_exec($ch);

//close connection
curl_close($ch);

//write to file
$fp = fopen('uploads/result.pdf', 'w');  //make sure the directory markdown.md is in and the result.pdf will go to has proper permissions
fwrite($fp, $result);
fclose($fp);

Problem

I'm trying to use Docverter to convert LaTeX/markdown files to PDF but am having trouble using PHP to do CURL to access Docverter via their API. I'm know I'm not a total idiot b/c i can get this to work adapting the shell script in this Docverter example and running from command line (Mac OSX). Using PHP's `exec()`: ``` $url=$_SERVER["DOCUMENT_ROOT"]; $file='/markdown.md'; $output= $url.'/markdown_to_pdf.pdf'; $command="curl --form from=markdown \ --form to=pdf \ --form input_files[]=@".$url.$file." \ http://c.docverter.com/convert > ".$output; exec("$command"); ``` This gives no error messages but doesn't work. Is there a path issue somewhere? UPDATE Based on @John's suggestion, here's an example using PHP's `curl_exec()` adapted from here. Unfortunately this also doesn't work though at least it gives error messages. ``` $url = 'http://c.docverter.com/convert'; $fields_string =''; $fields = array('from' => 'markdown', 'to' => 'pdf', 'input_files[]' => $_SERVER['DOCUMENT_ROOT'].'/markdown.md', ); //url-ify the data for the POST foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; } rtrim($fields_string, '&'); //open connection $ch = curl_init(); //set the url, number of POST vars, POST data curl_setopt($ch,CURLOPT_URL, $url); curl_setopt($ch,CURLOPT_POST, count($fields)); curl_setopt($ch,CURLOPT_POSTFIELDS, $fields_string); //execute post $result = curl_exec($ch); //close connection curl_close($ch); ```

Original source