Question

我要根据所选的其他下拉列表更改下拉值。这是HTML

 <select class="form-control" name="category_id" formControlName="category_id" (change)="changeProfession($event.target.value)">
                                    <!-- <option value="" d>Select Category (required)</option> -->
                                    <option *ngFor='let surveyCategory of surveyCategoryList' [ngValue]="surveyCategory._id">{{ surveyCategory.category }}</option>
                                    <app-field-error-display [displayError]="this.validationService.isFieldValid(updateProfileForm,'category_id')">
                                    </app-field-error-display>
                               </select>

在这里我想根据所选类别获得价值

<div class="form-group label-floating select_lang">
                                <label class="control-label">Profession</label>
                                <select class="form-control" name="profession_id" formControlName="profession_id" >
                                     <!-- <option value="" >Select Category (required)</option> -->
                                    <option *ngFor='let profession of ProfessionList' [ngValue]="profession._id">{{ profession.profession }}</option>
                                    <app-field-error-display [displayError]="this.validationService.isFieldValid(updateProfileForm,'profession_id')">
                                    </app-field-error-display>
                               </select>

                            </div>

这是ts文件

changeProfession(categoryid){
    debugger;
    this.authService.getProfessionList(categoryid).subscribe(data => {
        debugger;
        if (data.success) {
            debugger;
            this.ProfessionList = data.profession;
            console.log(data);
            setTimeout(() => {
            //if (obj.survey_category_id)
                    //this.updateProfileForm.controls['profession_id'].setValue(obj.profession_id._id);
                 $('.select_lang').removeClass('is-empty');
            }, 10);
        }

    });
}

这是服务文件

// Get survey profession list
 getProfessionList = function (categoryid) {
     debugger;
    return this.http.get(this.api_url + 'profession/list/'+ categoryid, this.getAuthHeaderOption()).map(res => res.json());
}

当我调用此事件时，类别ID正在传递，但未显示值。请在这里告诉我我在做什么错。

Answer 1

实现需求的Angular方法与您完成的方法稍有不同。

在您的component.ts文件中，在以下代码中初始化表格：

 this.sampleForm.controls['category_id'].valueChanges.subscribe((value) => {
       this.authService.getProfessionList(value).subscribe(data => {
            this.ProfessionList = data.profession;
       }); 
 });

用您的sampleForm名称替换formGroup。另外请注意，data.profession的值应为对象数组。

以下是Stackblitz链接的示例示例：Working Demo

如何在Angular 4中使用打字稿显示基于其他下拉选择值的下拉值

1 个答案: