robtimus/multipart

A library to support (streaming) multiparts

1.0 2018-10-27 18:53 UTC

This package is auto-updated.

Last update: 2022-04-29 01:37:19 UTC


README

A library to support (streaming) multiparts.

Supported multipart types

multipart/form-data

To create a multipart/form-data object, create a MultipartFormData instance, add the form fields, and call finish(). There are two methods for adding form fields:

  • addValue($name, $value) adds a string value with the given name. Both arguments are required.
  • addFile($name, $filename, $content, $contentType, $contentLength = -1) adds a file with the given name. The name, filename, content and content type are required; the content length is optional, and will be ignored if the content is a string.

An example:

// the multipart object can take an optional pre-existing boundary
$multipart = new MultipartFormData();
$multipart->addValue('name', 'Rob');
$multipart->addFile('file', 'file.txt', 'Hello World', 'text/plain');
$multipart->finish();

Multiple values or files with the same parameter name

MultipartFormData follows RFC 7578, and not RFC 2388. This means that multiple values or files with the same parameter name are not sent with a multipart/mixed field but instead as separate parts.

PHP servers require multiple values or files to be sent with a name that ends with []. Because MultipartFormData is written to support also other server types that do not have this requirement, it is up to the caller to add these. For instance:

$multipart = new MultipartFormData();
$multipart->addValue('name', 'Rob');
$multipart->addFile('file[]', 'file.txt', 'Hello World', 'text/plain');
$multipart->addFile('file[]', 'file.html', '<html>Hello World</html>', 'text/html');
$multipart->finish();

multipart/related

To create a multipart/related object, create a MultipartRelated instance, add the root part and any inline files, and call finish(). There are two methods for adding parts:

  • addPart($content, $contentType, $contentLength = -1, $contentTransferEncoding = '') adds a part without a content disposition. This should be used for the root part. The content and content type are required; the content length is optional, and will be ignored if the content is a string; the content transfer encoding is optional, and will be used for the Content-Transfer-Encoding header if it is set.
  • addInlineFile($contentID, $filename, $content, $contentType, $contentLength = -1, $contentTransferEncoding = '') adds an inline file. The content ID, filename, content and content type are required; the content length is optional, and will be ignored if the content is a string; the content transfer encoding is optional, and will be used for the Content-Transfer-Encoding header if it is set.

An example:

// the multipart object can take an optional pre-existing boundary
$multipart = new MultipartRelated();
$multipart->addPart(file_get_contents('body.html'), 'text/html');
// the content length is irrelevant because the content is a string
$multipart->addInlineFile('logo', 'logo.png', base64_encode(file_get_contents('logo.png')), 'image/png', -1, 'base64');
$multipart->finish();

To use this inline file in the HTML body, use cid:logo as the source of an image.

multipart/alternative

To create a multipart/alternative object, create a MultipartAlternative instance, add the alternatives, and call finish(). There are two methods for adding alternatives:

  • addMultipart(Multipart $multipart) adds another multipart as alternative. This is most often used with a multipart/related object.
  • addPart($content, $contentType, $contentLength = -1, $contentTransferEncoding = '') adds a part with the given content. The content and content type are required; the content length is optional, and will be ignored if the content is a string; the content transfer encoding is optional, and will be used for the Content-Transfer-Encoding header if it is set.

An example:

// the multipart object can take an optional pre-existing boundary
$multipart = new MultipartAlternative();
// $related is a MultipartRelated instance as created above
$multipart->addPart(file_get_contents('body.txt'), 'text/plain');
$multipart->addMultipart($related);
$multipart->finish();

multipart/mixed

To create a multipart/mixed object, create a MultipartMixed instance, add the parts, and call finish(). There are three methods for adding parts:

  • addMultipart(Multipart $multipart) adds another multipart. This is most often used with a multipart/alternative or multipart/related object.
  • addPart($content, $contentType, $contentLength = -1, $contentTransferEncoding = '') adds a part with the given content. This can be used for the bodies of plain text emails. The content and content type are required; the content length is optional, and will be ignored if the content is a string; the content transfer encoding is optional, and will be used for the Content-Transfer-Encoding header if it is set.
  • addAttachment($filename, $content, $contentType, $contentLength = -1, $contentTransferEncoding = '') adds a part with content disposition attachment. The filename, content and content type are required; the content length is optional, and will be ignored if the content is a string; the content transfer encoding is optional, and will be used for the Content-Transfer-Encoding header if it is set.

An example:

// the multipart object can take an optional pre-existing boundary
$multipart = new MultipartAlternative();
// $alternative is a MultipartAlternative instance as created above
$multipart->addMultipart($alternative);
// the content length is irrelevant because the content is a string
$multipart->addFile('file.png', base64_encode(file_get_contents('file.png')), 'image/png', -1, 'base64');
$multipart->finish();

Multipart content

The content of a part or file can be given in one of three ways:

  • As a string. The content length will be ignored.
  • As a resource that can be read using fread. It is up to the caller to close this resource.
  • As a callable that takes a length, and returns a string that is not larger than the given length. If there is nothing more to read it should return the empty string.

Examples, using a MultipartFormData object:

// content length is not necessary
$multipart->addFile('file1', 'file.txt', 'Hello World', 'text/plain');

// make sure to close the resource after the request has been sent
$resource = fopen('file.html');
$multipart->addFile('file.html', $resource, 'text/html', filesize('file.html'));

// assume that class MyResource exists and has a function read($length)
$myResource = new MyResource(...);
$multipart->addFile('file.bin', array($myResource, 'read'), 'application/octet-stream');

cURL support

To send a multipart object with a cURL request, you need to follow some steps:

  • Set the request type using CURLOPT_CUSTOMREQUEST.
  • Set the CURLOPT_UPLOAD option to true.
  • Set the object's curl_read method as the CURLOPT_READFUNCTION.
  • Make sure the Content-Type and Content-Length headers are set. Note that the Content-Length header is optional.

For instance:

curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_UPLOAD, true);
curl_setopt($ch, CURLOPT_READFUNCTION, array($multipart, 'curl_read'));

$headers = ['Content-Type: ' . $multipart->getContentType()];
$contentLength = $multipart->getContentLength();
if ($contentLength >= 0) {
    $headers[] = 'Content-Length: ' .  $contentLength;
}
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

Non-streaming support

If streaming is not possible (e.g. because a string is required, like in the mail function), you can buffer a multipart object in-memory by calling the buffer method. This method takes an optional buffer size, and returns the buffered contents. The content length will be set accordingly. Note that you should do this before calling read (or curl_read), otherwise the buffered contents may not contain all desired contents (especially if you're using resources or callables).

Multipart.__toString() has been overridden to buffer the multipart object as well, so you can achieve the same by casting a multipart object to string. The difference is that buffer requires the multipart object to be finished.