如何避免 Angular 材质中出现额外的 mat-form-field-underline

Question

我遇到一个问题，为什么在使用组件时会出现额外的 mat-form-field-underline。

我的页面使用此标记：

<mat-form-field class="col-md-6">
        <app-mat-select-all 
            [data]="tractList$"
            formControlName="tractList"
            fieldName="name"
            [multiselect]=true
            labelText="Tract List"
            idField="guid"
            >
        </app-mat-select-all>
</mat-form-field>

我的自定义组件具有以下模板代码

<form novalidate [formGroup]="form">
    <mat-form-field>
    <mat-label>{{labelText}}</mat-label>
    <mat-select  #select [multiple]="multiselect" [formControl]="selectField" >
      <div class="select-all">
          <mat-checkbox *ngIf="multiselect" [(ngModel)]="allSelected"
                          [ngModelOptions]="{standalone: true}"
                          [indeterminate]="isIndeterminate()"
                          [checked]="isChecked()" 
                          (click)="$event.stopPropagation()"
                          (change)="toggleAllSelection($event)">{{text}}</mat-checkbox>
      </div>
      <mat-option *ngFor="let item of data" [value]="item[idField]">
        {{item[fieldName]}}
      </mat-option>
    </mat-select>
    </mat-form-field>
    </form>

在渲染的页面上看起来像这样

当我将以下行添加到我的父样式表中时，所有 mat-form-field-underlines 都消失了，这不是我想要的。如果我删除自定义组件中的 mat-form-field，我只会得到一行，但 mat-form-field-underline 的对齐方式与页面上的其他组件不对齐。所以我需要找到一种方法，只针对第二个下划线才能删除。

    ::ng-deep .mat-form-field-underline {
        display: none;
    }

这是一个 stackblitz 示例，演示了第二下划线的问题 StackBlitz 示例

这是我检查时的代码，似乎由于某种原因在 mat-form-field 内有一个 mat-form-field。不知道为什么？

<mat-form-field _ngcontent-jtb-c709="" class="mat-form-field col-md-6 ng-tns-c393-17 mat-primary mat-form-field-appearance-legacy mat-form-field-can-float mat-form-field-hide-placeholder"><div class="mat-form-field-wrapper ng-tns-c393-17"><div class="mat-form-field-flex ng-tns-c393-17"><!--bindings={
  "ng-reflect-ng-if": "false"
}--><!--bindings={
  "ng-reflect-ng-if": "0"
}--><div class="mat-form-field-infix ng-tns-c393-17"><app-mat-select-all _ngcontent-jtb-c709="" formcontrolname="tractList" fieldname="name" labeltext="Tract List" idfield="guid" _nghost-jtb-c804="" ng-reflect-field-name="name" ng-reflect-label-text="Tract List" ng-reflect-id-field="guid" ng-reflect-name="tractList" ng-reflect-form-control-name="tractList" class="ng-tns-c393-17 ng-untouched ng-pristine ng-valid" ng-reflect-multiselect="true" ng-reflect-data="[object Object],[object Object"><form _ngcontent-jtb-c804="" novalidate="" ng-reflect-form="[object Object]" class="ng-untouched ng-pristine ng-valid"><mat-form-field _ngcontent-jtb-c804="" class="mat-form-field ng-tns-c393-18 mat-primary mat-form-field-type-mat-select mat-form-field-appearance-legacy mat-form-field-can-float mat-form-field-has-label mat-form-field-hide-placeholder ng-untouched ng-pristine ng-valid"><div class="mat-form-field-wrapper ng-tns-c393-18"><div class="mat-form-field-flex ng-tns-c393-18"><!--bindings={
  "ng-reflect-ng-if": "false"
}--><!--bindings={
  "ng-reflect-ng-if": "0"
}--><div class="mat-form-field-infix ng-tns-c393-18"><mat-select _ngcontent-jtb-c804="" role="combobox" aria-autocomplete="none" aria-haspopup="true" class="mat-select ng-tns-c500-19 ng-tns-c393-18 ng-star-inserted mat-select-empty mat-select-multiple ng-untouched ng-pristine ng-valid" ng-reflect-multiple="true" ng-reflect-form="[object Object]" aria-labelledby="mat-form-field-label-19 mat-select-value-15" id="mat-select-14" tabindex="0" aria-expanded="false" aria-required="false" aria-disabled="false" aria-invalid="false"><div cdk-overlay-origin="" class="mat-select-trigger ng-tns-c500-19"><div class="mat-select-value ng-tns-c500-19" ng-reflect-ng-switch="true" id="mat-select-value-15"><span class="mat-select-placeholder mat-select-min-line ng-tns-c500-19 ng-star-inserted"></span><!--bindings={
  "ng-reflect-ng-switch-case": "true"
}--><!--bindings={
  "ng-reflect-ng-switch-case": "false"
}--></div><div class="mat-select-arrow-wrapper ng-tns-c500-19"><div class="mat-select-arrow ng-tns-c500-19"></div></div></div><!--bindings={
  "ng-reflect-offset-y": "0"
}--></mat-select><span class="mat-form-field-label-wrapper ng-tns-c393-18"><label class="mat-form-field-label ng-tns-c393-18 mat-empty mat-form-field-empty ng-star-inserted" ng-reflect-disabled="true" id="mat-form-field-label-19" ng-reflect-ng-switch="true" for="mat-select-14" aria-owns="mat-select-14"><!--bindings={
  "ng-reflect-ng-switch-case": "false"
}--><mat-label _ngcontent-jtb-c804="" class="ng-tns-c393-18 ng-star-inserted">Tract List</mat-label><!--bindings={
  "ng-reflect-ng-switch-case": "true"
}--><!--bindings={
  "ng-reflect-ng-if": "false"
}--></label><!--bindings={
  "ng-reflect-ng-if": "true"
}--></span></div><!--bindings={
  "ng-reflect-ng-if": "0"
}--></div><div class="mat-form-field-underline ng-tns-c393-18 ng-star-inserted"><span class="mat-form-field-ripple ng-tns-c393-18"></span></div><!--bindings={
  "ng-reflect-ng-if": "true"
}--><div class="mat-form-field-subscript-wrapper ng-tns-c393-18" ng-reflect-ng-switch="hint"><!--bindings={
  "ng-reflect-ng-switch-case": "error"
}--><div class="mat-form-field-hint-wrapper ng-tns-c393-18 ng-trigger ng-trigger-transitionMessages ng-star-inserted" style="opacity: 1; transform: translateY(0%);"><!--bindings={
  "ng-reflect-ng-if": ""
}--><div class="mat-form-field-hint-spacer ng-tns-c393-18"></div></div><!--bindings={
  "ng-reflect-ng-switch-case": "hint"
}--></div></div></mat-form-field></form></app-mat-select-all><span class="mat-form-field-label-wrapper ng-tns-c393-17"><!--bindings={
  "ng-reflect-ng-if": "false"
}--></span></div><!--bindings={
  "ng-reflect-ng-if": "0"
}--></div><div class="mat-form-field-underline ng-tns-c393-17 ng-star-inserted"><span class="mat-form-field-ripple ng-tns-c393-17"></span></div><!--bindings={
  "ng-reflect-ng-if": "true"
}--><div class="mat-form-field-subscript-wrapper ng-tns-c393-17" ng-reflect-ng-switch="hint"><!--bindings={
  "ng-reflect-ng-switch-case": "error"
}--><div class="mat-form-field-hint-wrapper ng-tns-c393-17 ng-trigger ng-trigger-transitionMessages ng-star-inserted" style="opacity: 1; transform: translateY(0%);"><!--bindings={
  "ng-reflect-ng-if": ""
}--><div class="mat-form-field-hint-spacer ng-tns-c393-17"></div></div><!--bindings={
  "ng-reflect-ng-switch-case": "hint"
}--></div></div></mat-form-field>

Answer 1

当你这样做时：

::ng-deep .mat-form-field-underline {
  display: none;
}

这适用于具有此类的所有材质组件。您应该做的是将自定义类添加到 HTML 内的组件，然后在 SCSS 文件中像这样引用它：

<mat-form-field class="custom-class">
  ...
</mat-form-field>

::ng-deep .custom-class .mat-form-field-underline {
  display: none;
}

现在，只有该组件会受到

::ng-deep

覆盖的影响。

工作示例

Answer 2

在带有基于 MDC 的组件的 Angular-Material 15 及更高版本中，以下代码隐藏了 mat-select 的额外下划线，而不影响其他表单字段组件：

mat-form-field:has(mat-select) div[matformfieldlineripple] {
    display: none;
}

在这里，您将波纹 div 隐藏在 mat-form-fields 中，其中有 mat-select 。