how to user ajax with json in ruby on rails
- by fenec
I am implemeting a facebook application in rails using facebooker plugin, therefore it is very important to use this architecture if i want to update multiple DOM in my page.
if my code works in a regular rails application it would work in my facebook application.
i am trying to use ajax to let the user know that the comment was sent, and update the comments bloc.
migration:
class CreateComments < ActiveRecord::Migration
def self.up
create_table :comments do |t|
t.string :body
t.timestamps
end
end
def self.down
drop_table :comments
end
end
controller:
class CommentsController < ApplicationController
def index
@comments=Comment.all
end
def create
@comment=Comment.create(params[:comment])
if request.xhr?
@comments=Comment.all
render :json=>{:ids_to_update=>[:all_comments,:form_message],
:all_comments=>render_to_string(:partial=>"comments" ),
:form_message=>"Your comment has been added." }
else
redirect_to comments_url
end
end
end
view:
<script>
function update_count(str,message_id) {
len=str.length;
if (len < 200) {
$(message_id).innerHTML="<span style='color: green'>"+
(200-len)+" remaining</span>";
} else {
$(message_id).innerHTML="<span style='color: red'>"+
"Comment too long. Only 200 characters allowed.</span>";
}
}
function update_multiple(json) {
for( var i=0; i<json["ids_to_update"].length; i++ ) {
id=json["ids_to_update"][i];
$(id).innerHTML=json[id];
}
}
</script>
<div id="all_comments" >
<%= render :partial=>"comments/comments" %>
</div>
Talk some trash: <br />
<% remote_form_for Comment.new,
:url=>comments_url,
:success=>"update_multiple(request)" do |f|%>
<%= f.text_area :body,
:onchange=>"update_count(this.getValue(),'remaining');" ,
:onkeyup=>"update_count(this.getValue(),'remaining');"
%> <br />
<%= f.submit 'Post'%>
<% end %>
<p id="remaining" > </p>
<p id="form_message" > </p>
<br><br>
<br>
if i try to do alert(json) in the first line of the update_multiple function , i got an [object Object].
if i try to do alert(json["ids_to_update"][0]) in the first line of the update_multiple function , there is no dialog box displayed.
however the comment got saved but nothing is updated.
questions:
1.how can javascript and rails know that i am dealing with json objects?
2.how can i debug this problem?
3.how can i get it to work?
