API: add getMetaModel() to items interface IItems

[zonky2]

it´s possible to retrive the MetaModels per item - if the count of items zero, it´s not possible to ask the MetaModels and we should add this at IItems

[richardhj]

As it is an interface change and it would break semantic versioning, the correct milestone would be 2.0.0.
As I just checked, the Items collection does not require that every Item belongs to the same MetaModel (see https://github.com/MetaModels/core/blob/2.0.0-alpha14/src/MetaModels/Items.php#L43-L51). Am I right? If so, there might be multiple MetaModel instances belonging the the Items collection.

[richardhj]

Is there a reasonable use case? Don't see so at first sight. Items is just a wrapper class, to enable iterating trough items.

[zonky2]

use case e.g. https://community.contao.org/de/showthread.php?66171-TableName-des-MM-im-Frontend-zur-Verf%C3%BCgung&p=436153&viewfull=1#post436153

$strTableName = $this->items->getItem()->getMetaModel()->getTableName();

if getItem() zero we have a error...

I think, every item of items have the same MetaModel - or not?

[richardhj]

I think, every item of items have the same MetaModel - or not?

The code says: no
(Meaning it can not be assumed. The collection constructor must be adapted otherwise.)

[zonky2]

@discordier what do you mean...

[discordier]

IMO this is a breaking change as in #1087.
However, we have had to adjust some interfaces during the beta phase already (in DCG) and therefore we might squeeze this in also.
Yet I'd rather add the MetaModel name to the list template then rather than adding this new method which will be of no use usually.
In the end, it is just a convenience wrapper collection, as @richardhj has pointed out.

[richardhj]

Please add "up for discussion" for the point whether we should force an IItems collection belonging to one MetaModel instance.

[zonky2]

closed - see #1100 (comment)