动态行创建影响其他创建的下拉值角度 6

Question

我有3个下拉主要，次要，三元类别，每个类别相互依赖，最初我下面有3个下拉菜单，我有一个按钮"添加更多"，再次单击"添加更多"后，下降将低于之前有的，现在的问题是第一行下拉选择工作正常，单击"添加更多"后第二行下拉选择不起作用， 意味着它更改与三元类别相同的第二个类别中已选择的第一行的值。首先我都加载所有主要类别，基于主要 id 我将获取次要类别，基于次要类别 id 我将获取三元类别。请我用这个。

网页代码

<div class="row Space_2">
<div class="col-md-4">
<select class="Textfield_2" id="primary_category_id"  formControlName="primary_category_id" (change)="getSecondCategory($event.target.value)" name="primaryServices" required>
<option value="">Primary Service</option>
<option *ngFor="let primaryCat of primaryCategory" [value]="primaryCat.id">{{primaryCat.name}}</option>
</select>
</div>
<div class="col-md-4">
<select class="Textfield_2" id="secondary_category_id" formControlName="secondary_category_id" (change)="getTernaryCategory($event.target.value)" name="secondaryServices" required>
<option value="">Secondary Service</option>
<option *ngFor="let secondCat of secondCategory" [value]="secondCat.id">{{secondCat.name}}</option>
</select>
</div>
<div class="col-md-4">
<select class="Textfield_2" id="ternary_category_id"  formControlName="ternary_category_id" name="secondaryServices" required>
<option value="">Ternary Service</option>
<option *ngFor="let ternaryCat of ternaryCategory" [value]="ternaryCat.id">{{ternaryCat?.name}}</option>
</select>
</div>
</div>
<div *ngFor="let k of addmoreServices let i = index">
<div class="row Space_2">
<div class="col-md-4">
<select class="Textfield_2" id="primary_category"   (change)="getSecondCategory($event.target.value)" name="{{k.primary_category}}" required>
<option value="">Primary Service</option>
<option *ngFor="let a of primaryCategory" [value]="a.id">{{a?.name}}</option>
</select>
</div>
<div class="col-md-4">
<select class="Textfield_2" id="secondary_category" (change)="getTernaryCategory($event.target.value)"  name="{{k.secondary_category}}" required>
<option value="">Secondary Service</option>
<option *ngFor="let b of secondCategory" [value]="b.id">{{b?.name}}</option>
</select>
</div>
<div class="col-md-4">
<select class="Textfield_2" id="secondary_category" (change)="getTerId($event.target.value)" name="{{k.ternary_category}}" required>
<option value="">Ternary Service</option>
<option *ngFor="let c of ternaryCategory" [value]="c.id">{{c?.name}}</option>
</select>
</div>
</div>
</div>

打字稿代码：

getPrimaryCategory() {
this.http.get('http://localhost:3000/api/getPrimaryCategory' ,{
})
.subscribe(
res => {
this.primaryCategory = res['data'];
console.log(this.primaryCategory);

},
err => {
}
);
}
getSecondCategory(id,i) {
this.primcatId = id;
this.http.get('http://localhost:3000/api/getsecondarycatdataforternary/'+id ,{
})
.subscribe(
res => {
this.secondCategory = res['data'];
console.log(this.secondCategory);

},
err => {
}
);
}
getTernaryCategory(id) {
console.log("The ternary ID is",id);
this.secondId = id;
this.http.get('http://localhost:3000/api/getternaryCatforServices/'+id ,{
})
.subscribe(
res => {
this.ternaryCategory = res['data'];
console.log(this.ternaryCategory);

},
err => {
}
);
}
getTerId(id){
this.terid = id;
console.log("THE TERNARY ID IS",this.terid);
}
addMoreServices() {
this.addmoreServices.push({ primary_category:this.primcatId , secondary_category:this.secondId  ,ternary_category: this.terid });
console.log("the add more services",this.addmoreServices);
}

Answer 1

您需要将trackBy添加到*ngFor指令中。您可以按id跟踪，感谢您，这个 Angular 不会将刷新后的值视为新值。