类mysql的不喜欢按钮

<div class="container" *ngFor="let post of posts; let i = index "> <h6> {{post.description}} </h6> <div class="row"> <div class="col-md-3"> <div *ngFor="let like of likes; "> <div *ngIf="((post.user_id==like.user_id) && (post.post_id==like.post_id) && (like.like_status=='like'))"> <button type="button" class="btn btn-success" (click)=likeSubmit(post.user_id,post.post_id)><i class="fa fa-thumbs-up" aria-hidden="true"></i></button> </div> <div *ngIf="((post.user_id==like.user_id) && (post.post_id==like.post_id) && (like.like_status=='unlike'))"> <button type="button" class="btn btn-warning" (click)=likeSubmit(post.user_id,post.post_id)><i class="fa fa-thumbs-up" aria-hidden="true"></i></button> </div>  <div *ngIf="ngIf condition"> <button type="button" class="btn btn-basic" (click)=likeSubmit(post.user_id,post.post_id)><i class="fa fa-thumbs-up" aria-hidden="true"></i></button> </div>

这样做有点不正确,不需要在模板中执行内部循环,只需在组件逻辑中执行两个表的连接,然后只需呈现所需的数据。尝试将方法添加到连接两个表的组件中,然后可以轻松地在模板中执行所需的操作。例子:

Ts文件

...
    public getPostsWithLikes() {
        this.posts.map(post => {
            const like = this.likes && this.likes.find(plike => post.user_id === plike.user_id && post.post_id === plike.post_id);
            return {post, like};
        });
    }
...

Html文件

<div class="container" *ngFor="let item of getPostsWithLikes(); let i = index ">
   <h6> {{item.post.description}} </h6>
   <div class="row">          
     <div class="col-md-3">
         <div *ngIf="item.like && item.like.like_status=='like'">
                <button type="button" class="btn btn-success" (click)=likeSubmit(item.post.user_id,item.post.post_id)><i class="fa fa-thumbs-up"
                    aria-hidden="true"></i></button>
              </div>

         <div *ngIf="item.like && item.like.like_status=='unlike'">
                <button type="button" class="btn btn-warning" (click)=likeSubmit(item.post.user_id,item.post.post_id)><i class="fa fa-thumbs-up"
                    aria-hidden="true"></i></button>
              </div>

<!---if you don't have related record in likes table, like would be null (false), so you just need to invert it-->
       <div *ngIf="!item.like">
                <button type="button" class="btn btn-basic" (click)=likeSubmit(item.post.user_id,item.post.post_id)><i
                    class="fa fa-thumbs-up" aria-hidden="true"></i></button>
              </div>

希望能有所帮助。