Create a public read/write interface for $StylePluginBase::rendered_fields

Hope this one will not be corrupted ...

Well, I am porting to D8 a module (Views merge rows) because the current D7 maintainer doesn't seem to be active and I need this module. I re-used the code already there and changed many things. I have programming experience but I am new at module / drupal development. My goal was to port the module with minimal changes to make it work.

$rendered_fields was in the module code already and I was not aware of getField(). I try it and will comment back.

Here we go, the module implements hook_views_pre_render().

What is done outside of $view:
1) a $rendered_fields variable is created using renderFields(). I cannot use getField() here because I do not know ID of the fields in advance. If it were the case, I would have looped over row index.

2) this data is then manipulated on a per-field basis (settings vary by field): sum, count, merge data, and so on. This allows much more flexibility than the usual aggregate settings available in views.

3) Manipulated data is then put back in the StylePluginBase::$rendered_fields. Currenty, there is no way to set data back in $view because StylePluginBase::$rendered_fields is protected. I believe we could implement StylePluginBase::setField() here. I also need to unset non necessary rows in StylePluginBase::$rendered_fields.

You may find a copy the hook there: https://www.drupal.org/node/2826682

I just realized that renderFields() does not return any value. So I'd need to access $rendered_fields to get data as well.

@Lenlude:

I tried, but realized that the module wouldn't work with any basic AND custom views style (table, unformatted list, ...). This is clearly not the intent of Views Merge Rows module as one can expect merging to apply no matter what style is used.

Following my work on $DisplayPluginBase::extenders, I wrote functions to get/set the required information from/to $StylePluginBase::rendered_fields so making $stylePluginBase::rendered_fields public is no longer necessary. I had problems with git so I was unable to produce an interdiff file.

Changed title to make it in line with the proposed solution.

Oops, little typo here...

Really ... Big thanks !

@ dawehner:

This issue is clearly needed on top of #2824920: Make StylePluginBase::renderFields public. Fields have to be rendered prior to being able to use StylePluginBase::getRenderedFields() or StylePluginBase::setRenderedFields(). StylePluginBase::renderFields() does not provide any way to access StylePluginBase::rendered_fields.

As mentionned in issue #2824920: Make StylePluginBase::renderFields public, the module Views Merge Rows is a display extender plugin that modify Views output by implementing hook_views_pre_render(). Because the module needs to access $view->style_plugin->rendered_fields during pre-rendering process, and because $view->style_plugin->rendered_fields is not rendered prior to the execution ofhook_views_pre_render, invoking $view->style_plugin->renderFields($view->result) is made necessary. Then access methods can be used.

Here is a sample of the module code:

$view->style_plugin->renderFields($view->result);
$rendered_fields = $view->style_plugin->getRenderedFields();

Issue summary will be updated accordingly.

I guess this status is more appropriate because it has already been reviewed/tested.