Components: ng-template inside MatAutocomplete doesn't work

[fetis]

Reproduction

https://stackblitz.com/edit/angular-wwwm2h

Steps to reproduce:

1. Click on the input field

Expected Behavior

Autocomplete list is rendered on input click

Actual Behavior

Nothing is rendered

If you uncomment extra mat-option then list appears. I think ii's connected with the fact that autocomplete is unable to determine the number of options if they're coming from ng-template

Environment

• Angular: 8.2.14
• CDK/Material: 8.2.3
• Browser(s): any
• Operating System (e.g. Windows, macOS, Ubuntu): any

[crisbeto]

The autocomplete won't open if it doesn't pick up any options usingContentChildren. Projecting them in via ngTemplateOutlet like this isn't supported.

[fetis]

@crisbeto I recently implemented component where used QueryList.changes to track dynamic elements in projected content. Why not use it here as well?

[crisbeto]

The problem isn't that the content is projected, it's that the content is actually an ng-container which creates the items through a TemplateRef. This case won't be picked up by the QueryList.

[fetis]

so, is it a general Angular problem? Maybe we can address it to Angular team?

[crisbeto]

It's definitely a framework limitation, but I'm not sure that it's a bug since this is the way it has always worked.

[fetis]

ok, I see. Thanks for explanation

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