I have 2 files. app.ts and Child.ts
I am sending a variable from app to child and I want to detect any change in the variable and show data accordingly. I am not able to detect changes in a variable.
Any Help? I have attached Plunker Link and I have also explained what I want to do in Child.ts file in comments
App.ts File
//our root app component
import {Component, NgModule} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'
import {ChildCom} from './child.ts'
@Component({
selector: 'my-app',
template: `
<div>
<h2>Hello</h2>
<child-com newdata={{data}}></child-com>
</div>
`,
})
export class App {
data: any = [];
constructor(){
this.data = [{"name":"control","status":"false"}];
}
}
@NgModule({
imports: [ BrowserModule ],
declarations: [ App, ChildCom ],
bootstrap: [ App ]
})
export class AppModule {}
Child.ts File
import {Component, Input} from '@angular/core';
@Component({
selector: 'child-com',
template: `
<div>
<p>Controls: {{newdata}}</p>
</div>
`,
})
export class ChildCom {
@Input() newdata: any = [];
constructor(){
}
// here I want to check if the value of control in newdata variable is false
// then display a message on the front end "your controls are not working"
// if the value of control in newdata variable is true
// then display a message on front end "your controls are working fine."
// this should automatically happen whenever I change the value of newdata variable
}
Either you make newData
a setter or you implement OnChanges
export class ChildCom {
private _newdata: any = [];
@Input()
set newdata(value) {
// code here
}
}
export class ChildCom implements OnChanges {
@Input() set newdata(: any = [];
ngOnChanges(changes) {
// code here
}
}
https://angular.io/docs/ts/latest/api/core/index/OnChanges-class.html
hint
newdata={{data}}
is fine, but only supports string values
[newdata]=data
supports all types of values.
Here is a link to updated plnkr to explain the same, https://plnkr.co/edit/5ahxWJ?p=preview