API Refactor template layer

[GuySartorelli]

Includes the following large-scale changes:

• Impoved barrier between model and view layers
• Improved casting of scalar to relevant DBField types
• Improved capabilities for rendering arbitrary data in templates

Issue

• Abstract template layer into its own dedicated module #11322

[emteknetnz]

Need to update commit message / PR title

[emteknetnz]

Suggested change

	$value = $this->getRawDataValue($name, type: ViewLayerData::TYPE_PROPERTY);
	$value = $this->getRawDataValue($name);

[GuySartorelli]

Discussion about this can be in #11405 (comment)

[GuySartorelli]

Done

[emteknetnz]

Suggested change

	$value = $this->getRawDataValue($name, $arguments, ViewLayerData::TYPE_METHOD);
	$value = $this->getRawDataValue($name, $arguments);

[GuySartorelli]

Discussion about this can be in #11405 (comment)

[GuySartorelli]

Done

[emteknetnz]

Things looking good, this is mostly likely an issue at my end

I've tried copying https://github.com/GuySartorelli/silverstripe-twig to my local (I copied files, rather than using composer), and by adding the following line to TwigTemplateEngine::render() if (!$this->template) return ''; (this is so that it's tolerant of missing Something.twig files)

I was able to get the "global" method described in the twig module readme to work i.e. setting yml, and I was also about to get the controller method to work, by updating PageController, though I wasn't able to get the Model version to work by updating Page

I get that it's a highly experimental module, though I just need to double check with you that the ModelData::renderWith() is actually behaving as expected

// app/src/Page.php

    public function renderWith($template, ModelData|array $customFields = []): DBHTMLText
    {
        // $template = SSViewer::create($template, SSTemplateEngine::create());
        $template = SSViewer::create($template, TwigTemplateEngine::create());
        return parent::renderWith($template, $customFields);
    }

[GuySartorelli]

Yup, that works.
You need to explicitly render a page in a template (you're rendering the controller normally) with something like this (assuming the page has at least one child page):

<% loop $AllChildren %>
  $Me
<% end_loop %>

Alternatively, use something that isn't a page.

[GuySartorelli]

Just realised I didn't update the commit message per #11405 (review)
Done now. Won't redo sink since all I changed was the commit message.