[英]How to use Ajax to show first and only one comment as soon as it is created
目前,我的應用程序能夠將評論添加到已經具有評論的微博中。 以下是_micropost.html.erb
(簡體):
<li id="micropost-<%= micropost.id %>">
<span class="content">
<%= micropost.content %>
</span>
<span class="timestamp">
Posted <%= time_ago_in_words(micropost.created_at) %> ago.
~ <%= link_to "Comment", "#", class: "comment-link", remote: true %>
<% if micropost.comments.any? %>
~ <%= link_to "Show/hide comments", "#", class: "comments-link", remote: true %>
<% end %>
</span>
<% if logged_in? && (current_user == micropost.user || current_user.friend?(micropost.user)) %>
<div class="comment-section">
<%= form_for(current_user.comments.build, remote: true) do |f| %>
<%= f.hidden_field :micropost_id, value: micropost.id %>
<%= f.text_area :content, rows: "1", class: "comment_area" %>
<%= f.submit "Comment", class: "btn btn-primary btn-sm" %>
<% end %>
</div>
<% end %>
<div class="comments-section">
<% if micropost.comments.any? %>
<ol id="comments_micropost-<%= micropost.id %>">
<% micropost.comments.each do |comment| %>
<%= render comment %>
<% end %>
</ol>
<% end %>
</div>
</li>
create.js.erb
是:
var comments = $('ol#comments_micropost-<%= @micropost.id %>');
comments.append('<%= escape_javascript(render partial: @comment) %>');
在構思時, create.js.erb
意味着將創建的注釋添加到其他注釋中,也就是說,創建的注釋不是第一個。 在這種情況下, var comments
不為null,並且代碼的最后一行將注釋附加到其他注釋的列表中。
另外,如果micropost.comments不為零,則用戶可以使用“顯示/隱藏評論”鏈接來切換id="comments_micropost-<%= micropost.id %>"
的訂單。
這種配置的問題在於,如果用戶向任何微博添加了第一個評論(也就是說,當micropost.comments == 0
時用戶寫了他的評論),就沒有機會不刷新頁面就看到結果。
所以我問:如何編輯create.js.erb
以便用戶可以立即看到發布第一個評論的結果,並將“顯示/隱藏評論”鏈接添加到頁面?
我嘗試了以下代碼,但它不起作用:
if (comments !== null) {
comments.append('<%= escape_javascript(render partial: @comment) %>');
} else {
$('#micropost-<%= @micropost.id %>').find('.comments-section').append("<ol id='comments_micropost-<%= @micropost.id %>'><%= escape_javascript(render partial: @comment) %></ol>");
$('#micropost-<%= @micropost.id %>').find('.timestamp').append(" ~ <%= link_to 'Show/hide comments', '#', class: 'comments-link', remote: true %>");
};
<li id="micropost-<%= micropost.id %>">
<span class="content">
<%= micropost.content %>
</span>
<span class="timestamp">
Posted <%= time_ago_in_words(micropost.created_at) %> ago.
~ <%= link_to "Comment", "#", class: "comment-link", remote: true %>
<% if micropost.comments.any? %>
~ <%= link_to "Show/hide comments", "#", class: "comments-link", remote: true %>
<% end %>
</span>
<% if logged_in? && (current_user == micropost.user || current_user.friend?(micropost.user)) %>
<div class="comment-section">
<%= form_for(current_user.comments.build, remote: true) do |f| %>
<%= f.hidden_field :micropost_id, value: micropost.id %>
<%= f.text_area :content, rows: "1", class: "comment_area" %>
<%= f.submit "Comment", class: "btn btn-primary btn-sm" %>
<% end %>
</div>
<% end %>
<div class="comments-section">
<%= render partial: comments, micropost: micropost %>
</div>
</li>
並在_comments.html.erb中
<% if micropost.comments.any? %>
<ol id="comments_micropost-<%= micropost.id %>">
<% micropost.comments.each do |comment| %>
<%= render comment %>
<% end %>
</ol>
<% end %>
並在create.js.erb中
var comments = $('ol#comments_micropost-<%= @micropost.id %>');
if (comments == undefined) {
$('div#comments-section').html('<%= escape_javascript(render partial: comments, micropost: @micropost) %>');
}
else {
comments.append('<%= escape_javascript(render partial: @comment) %>');
};
我按照Minu最初建議的app/views/comments/_comments.html.erb
文件解決了創建問題,如下所示:
<% if @micropost.comments.any? %>
<ol id="comments_micropost-<%= @micropost.id %>">
<% @micropost.comments.each do |comment| %>
<%= render comment %>
<% end %>
</ol>
<% end %>
在不更改部分_micropost.html.erb
我對create.js.erb
進行了如下編輯:
var comments = $('ol#comments_micropost-<%= @micropost.id %>');
if (comments.length == 0) {
$('#micropost-<%= @micropost.id %>').find('.comments-section').html("<%= escape_javascript(render partial: 'comments/comments') %>");
}
else {
comments.append('<%= escape_javascript(render partial: @comment) %>');
};
什么時候micropost.comments.any?
如果為false,則var comments
不能為null
或undefined
,但是可以視為空數組,可以使用網絡瀏覽器控制台進行驗證。 因此,使用if (comments.length == 0)
。 請參閱Stackoverflow上的帖子 。
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