Adjusted TransportBuilder prepareMessage method to support text/plain…

[twoonesixdigital]

Description (*)

As of 2.3.3, Magento's Magento\Framework\Mail\Template\TransportBuilder class can no longer send emails whose "Content-Type" header is set to "text/plain". This is because the TransportBuilder's prepareMessage method does not pass the determined template type to the mimePartInterfaceFactory's create method. When no "type" key is present in the array passed to the create method, the mimePartInterfaceFactory defaults to "text/html".

This pull request simply modifies the prepareMessage method so that it passes the previously determined template type to the mimePartInterfaceFactory's create method.

Fixed Issues (if relevant)

1. Fixed TransportBuilder unable to send emails of Content-Type "text/plain" as of 2.3.3 #26471: TransportBuilder unable to send emails of Content-Type "text/plain" as of 2.3.3

Manual testing scenarios (*)

1. Define an email template of type "text" via an email_templates.xml file
2. Attempt to use the TransportBuilder's sendMessage() method to send an email based on that template:

$transport = $this->TransportBuilder->setTemplateIdentifier('some_template_id')
	->setTemplateOptions(['area' => \Magento\Framework\App\Area::AREA_ADMINHTML, 'store' => \Magento\Store\Model\Store::DEFAULT_STORE_ID])
	->setFrom("email@domain.com")
	->addTo("email@domain.com")
	->getTransport()
	->sendMessage();

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

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[fooman]

I know the variable name is not coming from you but it looks like that $part is never defined as an array prior. Since it only uses type maybe it makes sense to rename $part['type'] to $partType?

[twoonesixdigital]

I would agree. I suspect usage of the $part array is probably an artifact of an older version of the class. Replacing that with something simpler and less ambiguous would likely reduce confusion.

[thiaramus]

The internal Magento team is working on this issue right now.
The fix will be based on commits from the author and delivered according to our internal processes. All original commits made by the author will be preserved.

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