Should mat-menu-item _triggersSubMenu be public?

[mertdeg2]

Bug, feature request, or proposal:

Feature request

Background

We couldn't use mat-menu directly because it didn't support our use cases. As a result, the code base I am working on has following components:

• own menu item component that wraps mat-menu-item.
• our own menu component that extends mat-menu.
• our own trigger directive that forks of matMenuTriggerFor

This worked for us, but we needed to set private _triggersSubMenu property here: https://github.com/angular/material2/blob/be84566caa61e4d59a93be1a84dbe7cfe090c8c1/src/lib/menu/menu-item.ts#L68

Should mat-menu-item take this as an @input() to make this component more extensible?

[mertdeg2]

@jelbourn

[crisbeto]

@mertdeg2 I'm not sure that making this property a part of the public API makes sense. It's something that is set by the MatMenuTrigger whenever it's on the same element as MatMenuItem.

Regarding use cases that aren't being handled by MatMenu at the moment, can you post some examples of what those cases are? It might be beneficial to add support for them in Material so you don't have to fork the components in the first place.

[mertdeg2]

@chrisbubernak

[mertdeg2]

Talked to my colleague about this. We needed fixed headers/footers, complex menu item templates, async data loading + infini scroll. I believe when we started forking matMenu not all of these features were present. Not sure what the current state of matMenu is.

[crisbeto]

@mertdeg2 here's the status of the points from above:

• We don't have support for fixed headers/footers, but it shouldn't that big of an issue to add them.
• I'm not completely sure what you mean by async data loading. Is it about fetching data from a server or just rendering the menu asynchronously? If it's the latter, we added the ability to defer the rendering of the menu in feat(menu): support lazy rendering and passing in context data #9271.
• Regarding infinite scroll, it should be possible to use the upcoming virtual scrolling utilities together with MatMenu.