离子 2 聊天页面重复相同的值

Question

我正在使用离子2

这是我的模板代码

 <div class="messagesholder" *ngFor="let chat of chatval | orderby:'[date]'; let last = last">
           {{last ? callFunction() : ''}}  
         <div *ngIf="chat.sender == currentuser || chat.receiver == currentuser">
                   <p *ngIf="msgdate === undefined"  class="chat-date" #ChatDate id="ChatDate" >{{chat.date | amDateFormat:'LL'}}</p>
                   {{checkdate(chat.date)}}
         </div> 
         <div class="message" *ngIf="chat.sender == currentuser || chat.receiver == currentuser" [ngClass]="{'me': currentuser == chat.sender}">
                <div class='image' *ngIf="chat.path" >
                  <img *ngIf="chat.path" [src]="chat.path" imageViewer/><br>
                  <span *ngIf="chat.path_text">{{chat.path_text}}</span>
                  <span style="font-size:9px;">{{chat.date | amDateFormat:'hh:mmA'}}</span>
                </div> 
                 <div *ngIf="chat.message_text">
                 <span>{{chat.message_text}}</span>
                 <span style="font-size:9px;">{{chat.date | amDateFormat:'hh:mmA'}}</span>
                 </div>
          </div>
     </div>

这是我的函数

checkdate(i)
  {
    console.log("date");
    console.log(i);
    this.msgdate=i;
  }

我需要相同的日期值不要重复。因为我使用这个函数{{checkdate(chat.date(}}获取输入元素值。

但是我得到了这个错误。

Error in ./ChatPage class ChatPage - caused by: Expression has changed after it was checked. Previous value: 'true'. Current value: 'false'.

我该如何解决这个问题...

请告诉我，

谢谢

Answer 1

您收到以下错误，因为您正在尝试修改在循环语句中执行后端进程的对象。

Error in ./ChatPage class ChatPage - caused by: Expression has changed after it was checked. Previous value: 'true'. Current value: 'false'.

如果您想获得唯一的日期，那么您可以尝试以下示例，它将为您提供集合中唯一的聊天日期：

let Values = this.chatval.map(function (item) { return item["date"]; }).filter(this.OnlyUnique);
OnlyUnique(value, index, self): any {
    return self.indexOf(value) === index;
}