Why does my function output " the method 'forTemplate' does not exist on 'SilverStripe\View\ArrayData"

user_12531714 0
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This will be my very first question on here. I hope I give you all the info you need.

I am running a personal project using silverstripe v4.8 In my template, I have a optionsetfield, which is basically just a radiofield. The first 3 items in the options, I have hardcoded. I wrote another function for the rest to basically get me all the names of people who can make events, loop through them, and add them as options.

When I dump my outcome, it seems to come out the way I want it:

array (size=1)
  'Rick' => string 'Rick' (length=4)

But when I try to see it in my template, it gives me:

Object->__call(): the method 'forTemplate' does not exist on 'SilverStripe\View\ArrayData'

Now when I don't add the function to my Optionset, the first 3 hardcoded items work fine.

I will post my OptionsetField and the other function below. Thank you in advance

  public function createEventsFilterForm()
{
    $form = Form::create();

    $form = FieldList::create([
        OptionsetField::create('Eventfilters')
            ->setTitle('')
            ->setSource([
                'past' => 'Verlopen',
                'today' => 'Vandaag',
                'future' => 'Toekomst',
                $this->getFirstNameOfEvents()
            ])
    ]);

    return $form;
}

public function getFirstNameOfEvents()
{

    $allEvents = UpcomingEvents::get();
    foreach ($allEvents as $event) {

        $firstName = 'NVT';

        $memberProfileID = $event->MemberProfileID;

        if ($memberProfileID) {
            $firstName = [MemberProfile::get()->byID($memberProfileID)->FirstName];
        }

        $output = ArrayLib::valuekey($firstName);

        return $output;
    }
}
silverstripe arrays php
1 Answers

tl;dr:

SilverStripe templates cannot handle arrays. I guess the array got automatically converted to an ArrayData object.

if you want to be more explicit, you can write:

return new ArrayData([
  'Name' => "FOOBAR"
]);

and then in the template:

$FirstNameOfEvent <!-- this will also cause this error, because SSViwer does not know how to render ArrayData -->

<!-- but you can access object properties, like the Name that we defined: -->
$FirstNameOfEvent.Name <!-- will output FOOBAR -->

Long explanation:

forTemplate is a called by the SSViewer when rendering objects.
Basically, it's the SilverStripe equivalent to __toString(), whenever you are trying to output a object to the browser in a SilverStripe template, SSViewer (the renderer) will call forTemplate on that object.

Let me give an example:

class Foo extends VieableData {
  public $message = 'Hello World';
  public function forTemplate() {
    return "This is a foo object with the message '{$this->message}'";
  }
}
class PageController extends ContentController {
  public function MyFooObject() {
    return new Foo();
  }
}

so if in your Page.ss template, you call $MyFooObject it will call the function of the same name and get an object. Because it's an object, SSViewer doesn't know how to render and will call Foo->forTemplate(). Which then will result in the output This is a foo object with the message 'Hello World'

ArrayData does not have a forTemplate method, thus you get the error. There are 2 ways to get around that[1]:

  • subclass ArrayData and implement a forTemplate method that turns your data into a string (or DBField object) that can be output to the browser
  • Don't try to render ArrayData in your Template, instead access the data directly (like in the tl;dr above, so $MyArrayData.MyField)[2]

[1]: the same is true for all objects
[2]: accessing object properties directly is always possible, even if you have a forTemplate method. forTemplate is just the default what to do if you don't specify a property.

EDIT:

sorry, I partially misunderstood your question/problem.
All the stuff I said above is still true, and important to understand, but it didn't answer your question.

I thought you are calling $getFirstNameOfEvents in the template, but actually, you are using it in a DropDownField (missed that part).
The thing about the SilverStripe CMS is, it also use the same templates system as the frontend for it's own things. So DropDownField will also use SSViewer to render. So my explanation is still true, it just happens inside DropDownField.ss which is a builtin template file. It does something like this:

<select>
<% loop $Source %>
  <option value="$Key">$Value</option>
<% end_loop %>
</select>

$Source here is your array ['past' => 'Verlopen', 'today' => 'Vandaag', 'future' => 'Toekomst', $this->getFirstNameOfEvents()] which is automatically converted into ArrayData objects.

Now, the problem is, it doesn't work the way you think it works:

// the result you want:
['past' => 'Verlopen', 'today' => 'Vandaag', 'future' => 'Toekomst', 'Rick' => 'Rick']

// the result your code produces:
['past' => 'Verlopen', 'today' => 'Vandaag', 'future' => 'Toekomst', 0 => ['Rick' => 'Rick']]

notice how you have an array inside an array. Because getFirstNameOfEvents returns an array.

So what you should actually do:

    $source = ['past' => 'Verlopen', 'today' => 'Vandaag', 'future' => 'Toekomst'];
    $source = array_merge($source, $this->getFirstNameOfEvents());

    $form = FieldList::create([
        OptionsetField::create('Eventfilters')
            ->setTitle('')
            ->setSource($source)
    ]);
user_11192630
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