Magento2 Dynamic System->Configuration Comments

Question

In Magento 1.x you could have dynamic comments on system->configuration fields by declaring your field in system.xml like this:

<field_code_here translate="label">
 <label>Label Here</label>
 <frontend_type>text</frontend_type>
 <sort_order>10</sort_order>
 <show_in_default>1</show_in_default>
 <show_in_website>1</show_in_website>
 <show_in_store>1</show_in_store>
 <comment>
 <model>[module]/field_comment</model><!-- this made it dynamic -->
 </comment>
</field_code_here>

Then you just need to create the [Namespace]/[Module]/Model/Field/Comment.php file with this content:

class [Namespace]_[Module]_Model_Field_Comment 
{
 public function getCommentText() //the method has to be named getCommentText
 {
 //do some calculations here
 return 'Some string based on the calculations';
 }
}

This way the field would have as comment what the getCommentText method from above returned.
Is there an alternative for Magento 2? It seams that I cannot attach a model to a comment tag. The system.xml is not validated by Magento/Backend/etc/system_file.xsd if I do.

• benmarks: Can you cite a use case?
• Marius: @benmarks For Magento 1, I got this from EE1.13. I hope I'm allowed to show it. It's from the system.xml for the Enterprise_SalesArchive module <comment><model>enterprise_salesarchive/system_config_backend_active</model></comment>. because of this comment model I would see in the system->configuration the number of archived orders. I've used this approach on numerous custom extensions and it worked on CE also. Obviously I cannot find a case in Magento 2. If I did I wouldn't be asking this question. I would just replicate that case.
• Marius: @benmarks. IN case you are wondering why I need it, I'm planning to clone this magento 1 extension github.com/tzyganu/stock-filter to magento 2, for learning purposes. And in that extension I used this comment model approach to show a message under a config field, depending on the value of an other config field
• benmarks: Hmm. I want to say that the comment field is static by design, and I wonder if this is a UX best practice. If there's variability based on another field, that should be part of the overall message. That said, I can understand your case. Might be worth a discussion or PR on our GitHub.
• Raphael at Digital Pianism: I'm voting to close this question as off-topic because this is related to a pre release version of Magento 2, more info here: meta.magento.stackexchange.com/questions/907/…

Answer 1

[EDIT]
In the latest magento version this is possible in a similar way as in M2. I fixed it :)

[Original Answer]

It seams that this feature is partially implemented in Magento 2. It doesn't work yet.
In the code that generates the configuration form there is the method Magento\Backend\Model\Config\Structure\Element\Field::getComment:

public function getComment($currentValue = '')
{
 $comment = '';
 if (isset($this->_data['comment'])) {
 if (is_array($this->_data['comment'])) {
 if (isset($this->_data['comment']['model'])) {
 $model = $this->_commentFactory->create($this->_data['comment']['model']);
 $comment = $model->getCommentText($currentValue);
 }
 } else {
 $comment = parent::getComment();
 }
 }
 return $comment;
}

This method should handle the case when the comment is generated by a model, but the validation schema does not allow a model tag inside the comment tag because the comment is defined like this:

<xs:element name="comment" type="xs:string" />

I already opened a ticked on github

• Eugene Tulika: Please see this PR for the instructions: github.com/magento/magento2/pull/2626
• Marius: I've seen that PR... Because I MADE IT :).
• Eugene Tulika: haha, I know :) just for the reference.