如何在Angular4中获取FormControl的值

Question

我在Angular4中有一些经验,但我只是继承了一段使用FormControls的代码,我不知道如何使用它们.我正在设置一个注释textarea,如果isRegulatoryAuditRequired的值等于false,则需要该注释.我已经获得了必填字段,但是如果value为false并且提交了表单,我需要显示消息"需要评论".这是我的HTML,有两个单选按钮,一个textarea和一条消息标签:

<div class="btnWrapper">
              <div class="leftBtn">
                <span class="col-xs-12 no-padding">
                  <label>
                    <input type="radio" id="radio1" class="app-input-radio" name="isRegulatoryAuditRequired" [value]="true"
                           [checked]="isRegulatoryAuditRequired==true" formControlName="isRegulatoryAuditRequired" />
                    <span class="app-input-radio pull-left"></span>
                    <span class="plx5 pull-left radioText ">Yes</span>
                  </label>
                </span>
              </div>
              <br />
              <div class="rightBtn">
                <span class="col-xs-12 no-padding">
                  <label>
                    <input type="radio" id="radio2" class="app-input-radio" name="isRegulatoryAuditRequired" [value]="false"
                           [checked]="isRegulatoryAuditRequired==false" formControlName="isRegulatoryAuditRequired" />
                    <span class="app-input-radio pull-left"></span>
                    <span class="plx5 pull-left radioText ">No</span>
                  </label>
                </span>
              </div>
            </div>
          </div>
        </div>
      </div>
      <div class="row mbx20">
        <div class="col-sm-4">
          <div>
            <label>Why is the regulatory audit being performed or provide additional comment?</label>
            <div>
              <textarea id="comments" name="Text1" [required]="isRegulatoryAuditRequired==false" cols="100" rows="2" formControlName="comments"></textarea>
              <label *ngIf="commentsRequired('comments')" style="color:red;font-weight:bold">Comments required</label>

            </div>

我需要评估'isRegulatoryAuditRequired'和'comments'FormControls的值,看看我是否应该显示'需要评论'消息.这是我正在尝试使用的方法,但它不起作用:

commentsRequired(controlName: string) {
        const control = (<FormControl>this.rotationForm.controls[controlName]);
        const isRegulatoryAuditRequired = (<FormControl>this.rotationForm.controls['isRegulatoryAuditRequired']);
if (isRegulatoryAuditRequired.value === false && control.value === '' && this.formSubmitAttempt) {
            return true;
        } else {
            return false;
        }
    }

'isRegulatoryAuditRequired.value'和'control.value'的值作为null打印到控制台,因此不显示消息.如何检索这些值？任何帮助将不胜感激.

Answer 1

你可以这样做this.rotationForm.get('comments').value会给你formControl的价值,然后你可以检查长度