Ability to loop through containers containing primitives in Silverstripe templates

[chrispenny]

Description

It would be great if we were able to pass simple numeric/non-associative arrays to Silverstripe templates for them to be output. MVP for me would also be when those arrays only contain simple data types (string, int, float, etc).

I think this is probably felt most (for me) when working with external data sources. Trying to output some simple indexed content all of a sudden requires a bunch of processing before you can return it to your template.

As an aside, in Silverstripe 3, this would work:

class MyController extends PageController
{
    public function ArrayListTest()
    {
        return new ArrayList(['item1', 'item2', 'item3']);
    }
}

<% loop $ArrayListTest %>
    $Me
<% end_loop %>

But now in Silverstripe 4 and 5, this results in an error:

[Emergency] Uncaught Error: Call to a member function XML_val() on string

Noting though, that I'd probably prefer to avoid needing to convert my array to an ArrayList, as that still requires processing.

Additional context or points of discussion

No response

Acceptance criteria

• It's possible for a developer to create an list of scalar values to be rendered in an SS template withouth the developer having to warp them in an ArrayData construct.
• Individual scalar value are escaped when rendered to eliminate any XSS risk.
• Primitive arrays can be passed to templates and can be looped through

New issues created

• Ability to use arrays in templates #11237

Kitchen-sink CI run

• https://github.com/emteknetnz/recipe-kitchen-sink/actions/runs/9090038106 < note that the failing test on bringyourownideas/silverstripe-maintainence is due to use of a forked version of silverstripe/framework)

PRs

• ENH Convert scalars and arrays to viewable data #11227
• ENH Rendering scalars in ArrayList in templates #11238
• DOC Convert primitves to DBField in iterables developer-docs#511

[GuySartorelli]

This is a good idea. The template engine should be able to check if the value it's operating on is an object or not, and if it's not an object give it the appropriate DBField casting (bool to DBBoolean, etc)

[maxime-rainville]

@GuySartorelli added this to the 5.3 milestone.

This looks like the potential for a quick win.

I added a very generic AC just to avoid pre-judging of the best way of doing this

I'm thinking of the top of my head:

• We could try to update the rendering logic so it can understand scalar values or array of scalar value implicitly. While this may be the most intuitive solution for the end developer, I suspect it might also be the most difficult to implement.
• Maybe we could update the SS Viewer logic so it automatically wrap up any scalar value it gets into some viewable data wrapper.
• Maybe we update ArrayList so when you give it a scalar value, it wraps it in a viewable data wrapper.

[GuySartorelli]

The first two options there are just an implementation detail, really. Whether SSViewer (or the template parser, etc etc) wraps the primitive or just deals with it directly doesn't really matter - what matters is that developers don't have to do that part themselves.

That third option would have to be in a major release, and goes in the wrong direction imo. I'd prefer to see ArrayList not wrap any values in ArrayData at all, even in the cases it currently does.

[GuySartorelli]

PRs merged