删除评论 - React js [英] Delete a comment - React js

问题描述

实际上，我一直在尝试在我的评论栏系统中添加删除评论功能。

Actually, I've been trying to add a 'Delete a comment' functionality to my Comment Box system.

这是我的代码： -

Here is my code:-

var Comment = React.createClass({
  handleClick: function(e){
    e.preventDefault();
    var commentId = this.props.comment.id;
    return this.props.onDelete(commentId);
  },
  render: function () {
    return (
      <div className="comment">
        <h4 className="commentAuthor">
          {this.props.comment.email}
        </h4>
          {this.props.comment.comment}
          <a onClick={this.handleClick}> &times; </a>
      </div>
      );
  }
});

var CommentList = React.createClass({
  handleDelete: function(commentId){
    return this.props.del(commentId);
  },
  render: function () {
    var commentNodes = this.props.comments.map(function (comment, index) {
      return (
        <Comment comment = {comment} onDelete = {this.handleDelete} key = {index} />
        );
    });

    return (
      <div className="commentList">
        {commentNodes}
      </div>
      );
  }
});

var CommentBox = React.createClass({
  getInitialState: function () {
    return {comments: []};
  },
  componentDidMount: function () {
    this.loadCommentsFromServer();
  },
  loadCommentsFromServer: function () {
    $.ajax({
      url: this.props.url,
      dataType: 'json',
      success: function (comments) {
        this.setState({comments: comments});
      }.bind(this),
      error: function (xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
    });
  },
  handleCommentSubmit: function(comment) {
    var comments = this.state.comments;
    var newComments = comments.concat([comment]);
    this.setState({comments: newComments});
    $.ajax({
      url: this.props.url,
      dataType: 'json',
      type: 'POST',
      data: {"comment": comment},
      success: function(data) {
        this.loadCommentsFromServer();
      }.bind(this),
      error: function(xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
    });
  },
  delc: function(commentId){
    $.ajax({
      url: this.props.url,
      data: {"id" : commentId},
      type: 'DELETE',
      dataType: 'json',
      success: function (comments) {
        this.setState({comments: comments});
      }.bind(this), 
      error: function(xhr, status, err) {
        console.error(this.props.url, status, err.toString());
      }.bind(this)
      });
  },
  render: function () {
    return (
      <div className="commentBox">
        <h1>Comments</h1>
        <CommentList del={this.delc} comments={this.state.comments} />
        <CommentForm onCommentSubmit={this.handleCommentSubmit}/>
      </div>
      );
  }
});

var CommentForm = React.createClass({
  handleSubmit: function() {
    var email = this.refs.email.getDOMNode().value.trim();
    var comment = this.refs.comment.getDOMNode().value.trim();
    this.props.onCommentSubmit({email: email, comment: comment});
    this.refs.email.getDOMNode().value = '';
    this.refs.comment.getDOMNode().value = '';
    return false;
  },

  render: function() {
    return (
      <form className="commentForm" onSubmit={this.handleSubmit}>
        <input type="email" placeholder="Your email" ref="email" />
        <input type="text" placeholder="Say something..." ref="comment" />
        <input type="submit" value="Post" />
      </form>
      );
  }
});

var ready = function () {
  React.renderComponent(
    <CommentBox url="18/comments.json" />,
    document.getElementById('art')
  );
};

$(document).ready(ready);

现在，当我尝试删除注释时，它会抛出一个错误，显示'Uncaught TypeError：undefined不是函数'

Now, when I try to delete a comment, it throws an error that says 'Uncaught TypeError: undefined is not a function'

切换到devTool上的'source'选项卡，我发现问题出现在'onDelete'函数中。

Switching to 'source' tab on devTool, I found that the problem is in 'onDelete' function.

它说'onDelete'函数未定义。

It says, 'onDelete' function is undefined.

我认为问题是由于'this'关键字，但我是不确定。

我该怎么做才能解决这个问题？如果我错过了什么，请告诉我。（我是新手）

What should I do to resolve this issue? Let me know if I'm missing out on something.(I'm a newbie)

提前谢谢。

推荐答案

传递给 map 的函数不会自动共享这个指向你的反应类。

The function passed to map will not automatically share a this pointer with your react class.

要在匿名函数中使用这个，请调用 .bind（this）在函数定义的末尾，产生一个函数，里面有这个。

To use this inside the anonymous function, call .bind(this) at the end of the function definition to yield a function with the expected this inside.

var commentNodes = this.props.comments.map(function (comment, index) {
    ...
});

成为：

var commentNodes = this.props.comments.map(function (comment, index) {
    ...
}.bind(this));

这篇关于删除评论 - React js的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！