Can't get ng-content's select to filter correctly

Issue

I’m trying to use ng-content to selectively display certain components in certain areas, but I’m not getting the filtering to work correctly.

I have a layout component which contains certain components which are marked with directives where they need to render.

    <standard-layout class="blah">
        <sample-navigation *navBarItem></sample-navigation>
        <sample-navigation *navBarItem></sample-navigation>
        <sample-form-1 *contentItem></sample-form-1>
        <sample-form-2 *contentItem></sample-form-2>
        <sample-form-3 *contentItem></sample-form-3>
        <sample-navigation *actionBarItem></sample-navigation>
        <sample-navigation *actionBarItem></sample-navigation>
    </standard-layout>

This is my contentItem directives:

@Directive(selector: '[contentItem]')
class ContentItemDirective implements AfterContentInit {
    final ViewContainerRef vcRef;
    final TemplateRef template;
    final ComponentResolver componentResolver;

    ContentItemDirective(this.vcRef, this.template, this.componentResolver);

    ComponentRef componentRef;

    @override
    ngAfterContentInit() async {
        final componentFactory =
        await componentResolver.resolveComponent(ContentItem);
        componentRef = vcRef.createComponent(componentFactory);
        (componentRef.instance as ContentItem)
            ..template = template;
    }

}

This is what my ContentItem looks like

@Component(
    selector: "content-item",
    host: const {
        '[class.content-item]': true,
    },
    template: """
        <template [ngTemplateOutlet]="template"></template>
    """,
    directives: const [NgTemplateOutlet]
)
class ContentItem {
    TemplateRef template;
}

Inside the standard-layout‘s template, when I do <ng-content select=""></ng-content>, it displays all the components as expected.

When I try and filter the components, it doesn’t seem to work:

CSS Filtering displays nothing:

<ng-content select=".content-item"></ng-content>

Filtering on the content-item tag itself display nothing either:

<ng-content select="[content-item]"></ng-content>

I’ve tried many permutations of the select=... and just can’t seem to get it working. Any ideas?

I’m on the Angular Dart 3.0.0 package.

Solution

Managed to get it working using @ContentChildren

Inside my StandardLayout component, I filtered the inputs using:

@ContentChildren(ContentItemDirective)
QueryList<ContentItemDirective> contentItems;

@ContentChildren(ActionBarItemDirective)
QueryList<ActionBarItemDirective> actionBarItems;

@ContentChildren(NavBarItemDirective)
QueryList<NavBarItemDirective> navBarItems;

Now inside the standard-layout template, can loop through the items and display the template using ngTemplateOutlet

        <nav class="nav1" #nav1>
            <div *ngFor="let item of navBarItems">
                <template [ngTemplateOutlet]="item.template"></template>    
            </div>
        </nav>

        <div class="content" #content>    
            <div *ngFor="let item of contentItems">
                <template [ngTemplateOutlet]="item.template"></template>    
            </div>
        </div>

        <nav class="nav2" #nav2>
            <div *ngFor="let item of actionBarItems">
                <template [ngTemplateOutlet]="item.template"></template>    
            </div>              
        </nav>

Answered By – Jan Vladimir Mostert

Answer Checked By – Gilberto Lyons (FlutterFixes Admin)