Accessing a property in a parent Component

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I have a property in a top level Component that is used data from a HTTP source like so (this is in a file called app.ts):

import {UserData} from './services/user-data/UserData';

Component({
    selector: 'app', // <app></app>
    providers: [...FORM_PROVIDERS],
    directives: [...ROUTER_DIRECTIVES],
    pipes: [],
    template: require('./app.html')
})
@RouteConfig([
    // stuff here
])

export class App {
    // Please note that UserData is an Injectable Service I have written
    userStatus: UserStatus;

    constructor(private userData: UserData) {
        this.userStatus = new UserStatus();
    }

    ngOnInit() {
        this.userData.getUserStatus()
            .subscribe(
            (status) => {
                this.userStatus = status; // I want to access this in my Child Components...
            },
            (err) => {console.log(err);},
            () => {console.log("User status complete");            }
        );
    }
}

Now, I have another Component that is a direct child of the top level Component and within it I would like to access the parent's property 'userStatus', here is the child:

Component({
    selector: 'profile',
    template: require('app/components/profile/profile.html'),
    providers: [],
    directives: [],
    pipes: []
})

export class Profile implements OnInit {
    constructor() {

    }

    ngOnInit() {
        // I want to have access with the parent App Component, 'userStatus' propety here... I only want to read this property
    }
}

Now in Angular 1.x this would be easy as I could reference $parent in my child controller or (ANTI PATTERN ALERT!!!) I could be so foolish to put this data in my $rootScope.

What would be the best way to access the parent in Angular 2?


Component interaction, What if we want to access the properties like state, methods etc of custom components from parent component in React ? The document. You can pass parent instance reference as parameter to child or you can save parent instance reference in some static class variable and then access and manipulate it from child. You can get parent instance reference inside OnInit with keyword this and pass as parameter or save in static class variable.


I had the same problem but I solved it differently. I don't know if it's a good way of doing it, but it works great for what I need.

I used @Inject on the constructor of the child component, like this:

import { Component, OnInit, Inject } from '@angular/core';
import { ParentComponent } from '../views/parent/parent.component';

export class ChildComponent{
    constructor(@Inject(ParentComponent) private parent: ParentComponent){

    }

    someMethod(){
        this.parent.aPublicProperty = 2;
    }
}

This worked for me, you only need to declare the method or property you want to call as public.

In my case, the AppComponent handles the routing, and I'm using badges in the menu items to alert the user that new unread messages are available. So everytime a user reads a message, I want that counter to refresh, so I call the refresh method so that the number at the menu nav gets updated with the new value. This is probably not the best way but I like it for its simplicity.

How to access child component's properties from parent component , I used ViewContainerRef to access parent, children and grandchildren varibales. I created a sample StackBlitz project as part of the answer. I  (a) To set or manipulate the message by Child1, it has to access Provider and set the states of the Provider. (b) To view/access the data by Child2, it has to access Provider to get the states. Step 3: Use MyProvider component as a Parent to the two children — Child1, Child2.


Accessing parent, child, grandchild component variables in Angular , This components has a title property that we use in its template: Now our nested component is ready to receive input from its parent component. I know how to access data from parent to child by selector " <child-selector  3 Ways to Communicate Between Components in Blazor. 1. EventCallbacks. We're going to start with EventCallbacks. EventCallback and EventCallback<T> were added to Blazor in .NET Core 3 Preview 3 2. Cascading Values. 3. State Container.


I made a generic component where I need a reference to the parent using it. Here's what I came up with:

In my component I made an @Input :

@Input()
parent: any;

Then In the parent using this component:

<app-super-component [parent]="this"> </app-super-component>

In the super component I can use any public thing coming from the parent:

Attributes:

parent.anyAttribute

Functions :

parent[myFunction](anyParameter)

and of course private stuff won't be accessible.

Passing data to and from a nested component in Angular 2, Parent uses local variable to access the Child in Template. Parent Template can access the child component properties and methods by creating the template  When it comes to passing data from parent to child component we use property binding. In this case, we send the data from the parent component to the child component using an attribute. This attribute can then be accessed within the child component using the @input decorator.


On Angular 6, I access parent properties by injecting the parent via constructor. Not the best solution but it works:

 constructor(@Optional() public parentComponentInjectionObject: ParentComponent){
    // And access like this:
    parentComponentInjectionObject.thePropertyYouWantToAccess;
}

Angular Pass data to parent component, The best way to access child state from a parent component is through callback functions, Property 'ref' does not exist on type 'IntrinsicAttributes & { children?: In case that you really need to access to a child state that is declared as a functional component (hooks) you can declare a ref in the parent component, then pass it as a ref attribute to the child but you need to use React.forwardRef and then the hook useImperativeHandle to declare a function you can call in the parent component.


How to access childs state from parent component in React, Accessing the Parent Component Instance. Similar to $root , we can access the parent component's properties with the $parent property from a  Since the parent-child interaction is not an easy task to do. But by having a reference for the parent component in the child component it would be much easier to interact. In my method, you need to first pass a reference of the parent component by calling the function of the child component. Here is the for this method. The Code For Child


Vue.js Components, Parent Component => Child Component : @Input — property binding properties to child component there by giving child access to its data. In the parent we'll render the Child component and we'll send as a property (in this case action) the handler function declared in the parent. The Child component in this case is very simple, it will draw a button which action Prop (sent in the parent component) will be triggered when the button is clicked:


Sharing Data between Angular Components, To access the props passed from the parent component, we can easily consume them into the child component, like this. DemoComponent.js. The parent property allows us to grab a reference to whatever is directly above the component in the hierarchy, which in most cases is the Root Container. We could then access any component on the Root Container using getComponent ("Component Name") and placing the name of the component we want to access within the parenthesis.