角度可观察链 [英] Angular Observable chaining
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问题描述
我所做的是:
A B C D E F
----------------------
2 4 6 2 5 7
3 3 6 0 6 8
3 6 5 1 6 8
5 0 1 1 1 5
1 2 2 0 1 5
WHY I AM Subscribing B to A , C-> B , because on change of A , B will change and on change of B -> C will change (its like excel) where there are formulas on each field and change of each field other field will change
ObservableB[i] = ObervableA[i];
ObservableC[i] = ObservableB[i].pipe();
ObservableD[i] = obbservableC[i].pipe(
Map(res => res +1)
);
ObservableE[i] = ObservableD[i].pipe();
ObservableF[i] = ObservableE[i].pipe();
还有
ObserveB = dropdown Observable
ObserveC = dropdown Observable
ObserveD = Dropdown Observable
ObserveE = Drop down Observable
ObserveF = dropdown Observable
Now:
ObserveA = ObservableA.pipe(
map(val =>
{
//map only unique values of ObservableA to ObserveA
}
)
);
类似地,对于ObserveB,ObserveC,ObserveD,ObserveE,ObserveF
Similarly for ObserveB, ObserveC , ObserveD , ObserveE , ObserveF
现在我想要的是: 在选择ObserveA或任何其他下拉列表时,其他下拉值应更改 例如,如果我选择
Now what I want is : On selection of ObserveA, or any other dropdown , other drop down values should change For example if I selected
注意:下拉菜单为多选
DropdownA values selected : 2,3
因此,其他下拉菜单值应自动重置(通过重置,我的意思是其他下拉菜单的可用选项应更改为)
So other dropdown values automatically should be reset ( by reset I mean available option should change for other dropdowns ) to
means for B dropdown available options should be : 4,3,6
ObserveC = 6,5 (only unique values in drop down)
ObserveD = 2,0,1
ObserveE = 5,6 (only unique values in drop down)
ObserveF = 7,8 (only unique values in drop down)```
Is this is achievable ??
推荐答案
以下代码如何?
exclude.pipe.ts:
@Pipe({ name: 'exclude' })
export class ExcludePipe implements PipeTransform {
transform(value: any[], ...args: any[]): any {
return value.filter(x => ![].concat.apply([], args).includes(x))
}
}
unique.pipe.ts:
@Pipe({ name: 'unique' })
export class UinquePipe implements PipeTransform {
onlyUnique = (value, index, self) => self.indexOf(value) === index;
transform(value: any[]: any {
return value.filter(this.onlyUnique)
}
}
app.component.ts:
@Component(...)
export class AppComponent {
observableA = of([2, 4, 6, 2, 5, 7])
observableB = of([3, 3, 6, 0, 6, 8])
observableC = of([3, 6, 5, 1, 6, 8])
observableD = of([5, 0, 1, 1, 1, 5])
observableE = of([1, 2, 2, 0, 1, 5])
}
app.component.html:
<ng-container *ngIf="observableA | async as A">
<ng-container *ngFor="let item of A | unique"> <td> {{ item }} </td></ng-container><br>
<ng-container *ngFor="let item of (observableB | async | unique | exclude :A)"> <td> {{ item }} </td></ng-container><br>
<ng-container *ngIf="observableB | async as B">
<ng-container *ngFor="let item of (observableC | async | unique | exclude :A:B)"> <td> {{ item }} </td></ng-container><br>
<ng-container *ngIf="observableC | async as C">
<ng-container *ngFor="let item of (observableD | async | unique | exclude :A:B:C)"><td> {{ item }} </td></ng-container><br>
<ng-container *ngIf="observableD | async as D">
<ng-container *ngFor="let item of (observableE | async | unique | exclude : A:B:C:D)"><td> {{ item }} </td></ng-container><br>
</ng-container>
</ng-container>
</ng-container>
</ng-container>
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