Angular Virtual Scroll Not Detecting Changes to Add Items for Reactive FormArray
I am working with the new control in Angular 7 and cannot seem to get it to recognize that I've added a new item to the array that is being displayed.
Here is my html:
<cdk-virtual-scroll-viewport class="list-container lg" [itemSize]="52.5">
<div *cdkVirtualFor="let state of statesObservable | async;" class="list-group-item">
<div class="state">{{state.name}}</div>
<div class="capital">{{state.capital}}</div>
</div>
</cdk-virtual-scroll-viewport>
and here is the setup for the component:
import { Component, OnInit } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Component({
selector: 'app-virtual-scroll',
templateUrl: './virtual-scroll.component.html',
styleUrls: ['./virtual-scroll.component.css']
})
export class VirtualScrollComponent {
states = [
{ name: 'Alabama', capital: 'Montgomery' },
{ name: 'Alaska', capital: 'Juneau' },
];
statesObservable = new BehaviorSubject(this.states);
sortBy(prop: 'name' | 'capital') {
// this works -- creates a new array
this.statesObservable.next(this.states.map(s => ({ ...s })).sort((a, b) => {
const aProp = a[prop], bProp = b[prop];
if (aProp < bProp) {
return -1;
} else if (aProp > bProp) {
return 1;
}
return 0;
}));
}
addItem() {
// this does not work
this.states.push({ name: 'Wyoming', capital: 'Cheyenne' });
this.statesObservable.next(this.states);
}
}
I've created a stackblitz of the issue (based on an existing stackblitz that I found):
https://stackblitz.com/edit/angular-material-wlrjys
The very weird thing is that if you recreate the array by using a map function, it works and and the newly added items appear.
I've traced the issue into the guts of core.js and it looks as if it's not seeing the change to the array when I call .next() on the BehaviorSubject.
Any help is appreciated --
UPDATE
Of course, 10 minutes after I post this (after two days of searching) I find (half) the answer I'm searching for. It looks like change detection is not picking this up because I'm not changing the variable itself, just adding to it. Which I understand. The question is, how do I get a new variable for an existing FormArray -- do I have to recreate the entire thing? Seems like overkill.
angular angular-material2 angular7 angular-cdk
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
add a comment |
I am working with the new control in Angular 7 and cannot seem to get it to recognize that I've added a new item to the array that is being displayed.
Here is my html:
<cdk-virtual-scroll-viewport class="list-container lg" [itemSize]="52.5">
<div *cdkVirtualFor="let state of statesObservable | async;" class="list-group-item">
<div class="state">{{state.name}}</div>
<div class="capital">{{state.capital}}</div>
</div>
</cdk-virtual-scroll-viewport>
and here is the setup for the component:
import { Component, OnInit } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Component({
selector: 'app-virtual-scroll',
templateUrl: './virtual-scroll.component.html',
styleUrls: ['./virtual-scroll.component.css']
})
export class VirtualScrollComponent {
states = [
{ name: 'Alabama', capital: 'Montgomery' },
{ name: 'Alaska', capital: 'Juneau' },
];
statesObservable = new BehaviorSubject(this.states);
sortBy(prop: 'name' | 'capital') {
// this works -- creates a new array
this.statesObservable.next(this.states.map(s => ({ ...s })).sort((a, b) => {
const aProp = a[prop], bProp = b[prop];
if (aProp < bProp) {
return -1;
} else if (aProp > bProp) {
return 1;
}
return 0;
}));
}
addItem() {
// this does not work
this.states.push({ name: 'Wyoming', capital: 'Cheyenne' });
this.statesObservable.next(this.states);
}
}
I've created a stackblitz of the issue (based on an existing stackblitz that I found):
https://stackblitz.com/edit/angular-material-wlrjys
The very weird thing is that if you recreate the array by using a map function, it works and and the newly added items appear.
I've traced the issue into the guts of core.js and it looks as if it's not seeing the change to the array when I call .next() on the BehaviorSubject.
Any help is appreciated --
UPDATE
Of course, 10 minutes after I post this (after two days of searching) I find (half) the answer I'm searching for. It looks like change detection is not picking this up because I'm not changing the variable itself, just adding to it. Which I understand. The question is, how do I get a new variable for an existing FormArray -- do I have to recreate the entire thing? Seems like overkill.
angular angular-material2 angular7 angular-cdk
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
add a comment |
I am working with the new control in Angular 7 and cannot seem to get it to recognize that I've added a new item to the array that is being displayed.
Here is my html:
<cdk-virtual-scroll-viewport class="list-container lg" [itemSize]="52.5">
<div *cdkVirtualFor="let state of statesObservable | async;" class="list-group-item">
<div class="state">{{state.name}}</div>
<div class="capital">{{state.capital}}</div>
</div>
</cdk-virtual-scroll-viewport>
and here is the setup for the component:
import { Component, OnInit } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Component({
selector: 'app-virtual-scroll',
templateUrl: './virtual-scroll.component.html',
styleUrls: ['./virtual-scroll.component.css']
})
export class VirtualScrollComponent {
states = [
{ name: 'Alabama', capital: 'Montgomery' },
{ name: 'Alaska', capital: 'Juneau' },
];
statesObservable = new BehaviorSubject(this.states);
sortBy(prop: 'name' | 'capital') {
// this works -- creates a new array
this.statesObservable.next(this.states.map(s => ({ ...s })).sort((a, b) => {
const aProp = a[prop], bProp = b[prop];
if (aProp < bProp) {
return -1;
} else if (aProp > bProp) {
return 1;
}
return 0;
}));
}
addItem() {
// this does not work
this.states.push({ name: 'Wyoming', capital: 'Cheyenne' });
this.statesObservable.next(this.states);
}
}
I've created a stackblitz of the issue (based on an existing stackblitz that I found):
https://stackblitz.com/edit/angular-material-wlrjys
The very weird thing is that if you recreate the array by using a map function, it works and and the newly added items appear.
I've traced the issue into the guts of core.js and it looks as if it's not seeing the change to the array when I call .next() on the BehaviorSubject.
Any help is appreciated --
UPDATE
Of course, 10 minutes after I post this (after two days of searching) I find (half) the answer I'm searching for. It looks like change detection is not picking this up because I'm not changing the variable itself, just adding to it. Which I understand. The question is, how do I get a new variable for an existing FormArray -- do I have to recreate the entire thing? Seems like overkill.
angular angular-material2 angular7 angular-cdk
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
I am working with the new control in Angular 7 and cannot seem to get it to recognize that I've added a new item to the array that is being displayed.
Here is my html:
<cdk-virtual-scroll-viewport class="list-container lg" [itemSize]="52.5">
<div *cdkVirtualFor="let state of statesObservable | async;" class="list-group-item">
<div class="state">{{state.name}}</div>
<div class="capital">{{state.capital}}</div>
</div>
</cdk-virtual-scroll-viewport>
and here is the setup for the component:
import { Component, OnInit } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
@Component({
selector: 'app-virtual-scroll',
templateUrl: './virtual-scroll.component.html',
styleUrls: ['./virtual-scroll.component.css']
})
export class VirtualScrollComponent {
states = [
{ name: 'Alabama', capital: 'Montgomery' },
{ name: 'Alaska', capital: 'Juneau' },
];
statesObservable = new BehaviorSubject(this.states);
sortBy(prop: 'name' | 'capital') {
// this works -- creates a new array
this.statesObservable.next(this.states.map(s => ({ ...s })).sort((a, b) => {
const aProp = a[prop], bProp = b[prop];
if (aProp < bProp) {
return -1;
} else if (aProp > bProp) {
return 1;
}
return 0;
}));
}
addItem() {
// this does not work
this.states.push({ name: 'Wyoming', capital: 'Cheyenne' });
this.statesObservable.next(this.states);
}
}
I've created a stackblitz of the issue (based on an existing stackblitz that I found):
https://stackblitz.com/edit/angular-material-wlrjys
The very weird thing is that if you recreate the array by using a map function, it works and and the newly added items appear.
I've traced the issue into the guts of core.js and it looks as if it's not seeing the change to the array when I call .next() on the BehaviorSubject.
Any help is appreciated --
UPDATE
Of course, 10 minutes after I post this (after two days of searching) I find (half) the answer I'm searching for. It looks like change detection is not picking this up because I'm not changing the variable itself, just adding to it. Which I understand. The question is, how do I get a new variable for an existing FormArray -- do I have to recreate the entire thing? Seems like overkill.
angular angular-material2 angular7 angular-cdk
angular angular-material2 angular7 angular-cdk
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
edited Nov 23 '18 at 15:50
John Azzolina
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
asked Nov 23 '18 at 15:35
John AzzolinaJohn Azzolina
487
487
add a comment |
add a comment |
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