form_for not submit all fields - ruby-on-rails

Question

Use a hidden field will fix my issue... i got it..
Hi All,
I am new to rails, trying to do some practice.
The app i am writing is trying to create a new "Post" See the view and controller below.
But it doesn`t work as what i expected...
the parameters pass to function "save", there is no "post_at" field...
How can i fix it???
Thanks
INFO: Parameters: {"authenticity_token"=>"Xc9VuvRL6GsUTaKyyNQxp8ovylEYwOMC+7hMcqdKizg=", "post"=>{"title"=>"First post", "content"=>"Write something"}, "commit"=>"save"}
View new_post.erb
<div class="post">
<% form_for #new_post, :url => { :action => "save" } do |f| %>
<p><%= f.error_messages %></p>
<br/>
<table>
<tr>
<td>Title</td>
<td><%= f.text_field :title %></td>
</tr>
<tr>
<td>Post at</td>
<td><%= #new_post.post_at %></td>
</tr>
<tr>
<td>Message</td>
<td><%= f.text_area :content, :cols => 100, :rows => 10 %></td>
</tr>
</table>
<br/>
<%= f.submit 'save'%>
<% end %>
</div>
Post Controler
class PostController < ApplicationController
def index
#all_posts = Post.find(:all)
render :action => "post"
end
def new
#new_post = Post.new
#new_post.post_at = Time.now
render :action => "new_post"
end
def save
#new_post = params[:post]
Post.create(#new_post)
redirect_to "/post"
end
end
Data Model:
class Post
include DataMapper::Resource
storage_names[:default] = "Post"
property :id, Serial
timestamps :at
property :title, String, :required => true, :length => 500
property :content, Text, :required => true, :lazy => false
property :post_at, DateTime
end

Answer 1

First off, your development will be a lot easier if you follow the REST principles.
Your controller should instead of save implement the create and update methods.
def index
#posts = Post.all
end
def new
#post = Post.new
end
def create
#post = Post.create(params[:post])
redirect_to #post
end
def show
#post = Post.get(params[:id])
end
def edit
#post = Post.get(params[:id])
end
def update
#post = Post.get(params[:id])
#post.update_attributes(params[:post])
redirect_to #post
end
def destroy
#post = Post.get(params[:id])
#post.destroy
redirect_to posts_path
end
This is a complete REST controller which has the views index.html.erb, new.html.erb, edit.html.erb, show.html.erb all in app/views/posts.
Sidenote: If you're new to Rails, it might be a good idea to learn how to use it with ActiveRecord before trying on DataMapper. That way you can use rails generate scaffold to get a full example of a way to do all this.

Answer 2

Your post_at value isn't a field, it's just displayed in the table. You want to do this:
<tr>
<td>Post at</td>
<td><%= f.datetime_select :post_at %></td>
</tr>
But in fact, there's more wrong with this code than that. For starters, Rails already has a field for this which will be set automatically called created_at. Next, your save action in your controller should be a create action to follow the Rails conventions.
I really think you should read the Getting Started guide which covers these basic fundamentals and then a book or two about Rails in more depth. These really teach you a lot.

Answer 3

Ryan is right about the cause of the problem.
If you need a readonly field then you could add a hidden field to make sure that the value is posted back:
<td><%= #new_post.post_at %><%= f.hidden_field :post_at %></td>
or you could replace it altogether with a readonly text_field:
<td><%= f.text_field :post_at, :readonly => true %></td>