Send base64 encoded file along with JSON via CURL in php

Question

I am trying to use CURL to send a file to PANDADOCS via their Create Document from File API call : https://developers.pandadoc.com/reference/create-document-from-pdf.

As well as sending the file I need to send a data object containing recipients etc. as JSON as part of the multipart/form-data string. I am unsure how to setup this call properly and I keep getting various error messages returned from their API such as "There is field called file"

Here is what I have so far:

    public function createDocument()
    {


        $p = getmypid();
        $m = "({$p}): PandaDoc::create document: ";


        $postfields         = array();
        $postfields['name'] = $this->document->name;
        $postfields['file']  = $this->document->file; //base 64 encoded PDF

        $recipients = array(
            array(
                'email'      => 'a.mcdoogle@test.com',
                'first_name' => 'Andrew',
                'last_name'  => 'Mcdoogle',
                'role'       => 'user',
                'signing_order' => 1
            )
        );


        $data = array();
        $data['recipients'] = $recipients;

        $owner = array(
            "email" => "john@example.com"
        );

        $data['owner'] = $owner;

        $postfields['data'] =  json_encode($data);

        $header = array("Authorization: API-Key {$this->api_key}", "Content-Type: multipart/form-data", "accept" => "application/json");

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
        curl_setopt($ch, CURLOPT_URL, $this->url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $postfields);


        $res = curl_exec($ch);

        if ($res === false) {
            $errno = curl_errno($ch);
            $error = curl_error($ch);
            error_log("{$m}cURL error: {$error} ({$errno})");
            throw new Exception("{$m}cURL error: {$error} ({$errno})");
        }

        $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

        curl_close ($ch);

        error_log("{$m}Results from PandaDoc: {$res}");

        $response = json_decode($res);

        return $response;

    }

Can anybody tell me what I am doing wrong?

Answer 1

This is wrong:

 $postfields['data'] =  json_encode($data);

I found their API documentation to be disconcerting.

Short tutorial:
Here is a simple multipart/form-data HTML form:
Below I translate this form to curl.

<form action="<url>" method="post" enctype="multipart/form-data">

<input type="text" name="name1" value="value1" >
<input type="text" name="name2" value="value2" >
<input type="text" name="name3" value="value3" >

<button type="submit">submit</button>
</form>

To send this in curl you have to put the form-data in the postfields.

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, '<url>');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLINFO_HEADER_OUT, true);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, "-----------------------------3303153187906175792551542585\r\nContent-Disposition: form-data; name=\"name1\"\r\n\r\nvalue1\r\n-----------------------------3303153187906175792551542585\r\nContent-Disposition: form-data; name=\"name2\"\r\n\r\nvalue2\r\n-----------------------------3303153187906175792551542585\r\nContent-Disposition: form-data; name=\"name3\"\r\n\r\nvalue3\r\n-----------------------------3303153187906175792551542585--\r\n");

$response = curl_exec($ch);

This is the request header:

Content-Length: 408
Content-Type: application/x-www-form-urlencoded
Accept: */*
Host: my_curl_test_site.com
X-Https: 1

And this is the request body:

-----------------------------3303153187906175792551542585
Content-Disposition: form-data; name="name1"

value1
-----------------------------3303153187906175792551542585
Content-Disposition: form-data; name="name2"

value2
-----------------------------3303153187906175792551542585
Content-Disposition: form-data; name="name3"

value3
-----------------------------3303153187906175792551542585

---

I base64 encode a pdf like this:

$pdf = base64_encode(file_get_contents('example.pdf'));

For your PandaDoc API

---

Here is the document field, notice the $pdf from above.

------BoundaryXXXXXXXXX
Content-Disposition: form-data; name="file"; filename="Sample PandaDoc PDF with Field Tags.pdf"
Content-Type: application/pdf;

$pdf
------BoundaryXXXXXXXXX

Your content-type may need to be application/pdf;base64
Their example use the binary data.

And here are your data fields

------BoundaryXXXXXXXXX
Content-Disposition: form-data; name="data"

{ 
   "name": "My minimal document",
   "url": "https://example.com/path/to/mydocument.pdf",
   "recipients": [
      {
       "email":"nobody@example.com"
      }
   ],
   "parse_form_fields": false
}
------BoundaryXXXXXXXXX

Source: https://developers.pandadoc.com/docs/upload-and-send-a-local-pdf