得到插值({{}}),其中表达式是预期的

Question

我有以下HTML但我得到了例外.怎么解决？

解析器错误:插值({{}})其中表达式位于[!(editForm.controls.field_item_exportExpression _ {{i}} ?. dirty && editForm.controls.field_item_exportExpression _ {{i}}？无效的第48列) ]

<div class="form-group">
  <label class="form-control-label" for="field_exportExpression">exportExpression</label>
  <input class="form-control" type="text" id="field_item_exportExpression_{{i}}" name="item_exportExpression_{{i}}" [(ngModel)]="datatype.items[i].exportExpression" required>
  <div [hidden]="!(editForm.controls.field_item_exportExpression_{{i}}?.dirty && editForm.controls.field_item_exportExpression_{{i}}?.invalid)">
   <small class="form-text text-danger" [hidden]="!editForm.controls.field_item_exportExpression_{{i}}?.errors?.required" dpTranslate="dataconfiguration.validation.required"> This field is
                            required. </small>
 </div>
</div>

以下不起作用.说[找到不需要的令牌.

[hidden]="!editForm.controls.['item_exportExpression_' + i]?.errors?.required 

以下不是抱怨[而是抱怨Cannot read property '0' of undefined

 [hidden]="!editForm.controls.item_exportExpression_[ i]?.errors?.required 

Answer 1

{{}} 永远不会和[prop]="..."或一起去(event)="..."

<small class="form-text text-danger" 
       [hidden]="!editForm.controls.['field_item_exportExpression_' + i]?.errors?.required" dpTranslate="dataconfiguration.validation.required"> This field is
                        required. 
</small>

Answer 2

有4种类型的绑定:

• 属性绑定即[]评估值所需
• 模型绑定即[()]无需特殊处理
• 插值绑定即{{}}可以与一般属性一起使用
• 事件绑定即()功能很好

要回答你的问题,这样的事情对我们有用:

<input type="checkbox" [id]="['model-'+i]" [(ngModel)]="model" name="model-{{i}}" (change)="changeHandler($event)" />

Answer 3

模板

<div [hidden]="!checkIfInvalid(i, 'item_exportExpression_')">
                            <small class="form-text text-danger" [hidden]="isRequiredError(i, 'item_exportExpression_')" dpTranslate="dataconfiguration.validation.required"> This field is
                                required. </small>
    </div>

零件

checkIfInvalid( index: number, field: string ): boolean {
        const control = this.getControl( index, field );
        if ( control && control.dirty && !control.valid ) {
            return true;
        }
        return false;
    }

    isRequiredError( index: number, field?: string ): boolean {
        const control = this.getControl( index, field );
        if ( control && control.getError( "required" ) ) {
            return true;
        }
        return false;
    }

Answer 4

像这样使用而不是插值

  <button class="btn btn-primary" title="Edit" (click)="showEditModal(record.id)"><i class="fa fa-edit"></i></button>