New to RoR - working through book have some questions

Rails
1

Greetings,

I’m new to Ruby on Rails. I’m working through “Agile Web D.
with Rails 3rd Edition” and it is going quite well. However, there
are times I don’t quite understand why I’m doing something. For
some items, I think I understand, but I would like some confirmation.
So, I’m going to post my questions here and I hope that someone can
help me in understanding.

In Chapter 9, I’m working on creating an AJAX-based shopping cart.

So, I’m replacing this:

<%= button_to “Add to Cart”, :action => ‘add_to_cart’, :id => product
%>

With this:

<% form_remote_tag :url => { :action => ‘add_to_cart’, :id =>
product } do %>
<%= submit_tag “Add to Cart” %>
<% end %>

Questions on this:

I can explain that the first second is doing this: “Use ruby helper
button_to to add a button for each item, and it calls the action
add_to_cart, passing back the product that was selected”

I can’t seem to be able to explain the second section. “The rails
helper form_remote_tag is called, which is similar to a method call
and the :url is similar to passing a parameter to a method. The
items between { and } are the values for the :url parameter.”
Correct?

What is the “submit_tag”? Is that similar to the input type=“submit”
in HTML? Is it basically saying, show a button?

Why is the do%> and <% end %> part needed? Is this saying do the
following ruby code?

The difference between the two seconds, as the book explains, is that
the second sends an AJAX request instead of a POST request. I read
that, I think I understand it, but I don’t exactly know why there is a
difference. Can someone explain?

I’ll just start with this. Thanks,

Andrew

2

On Sep 19, 8:40 pm, andrew [email protected] wrote:

<% form_remote_tag :url => { :action => ‘add_to_cart’, :id =>
I can’t seem to be able to explain the second section. “The rails
helper form_remote_tag is called, which is similar to a method call
and the :url is similar to passing a parameter to a method. The
items between { and } are the values for the :url parameter.”
Correct?

pretty much. What’s in the :url hash are routing options, ie the same
thing as the second parameter to button_to or link_to

What is the “submit_tag”? Is that similar to the input type=“submit”
in HTML? Is it basically saying, show a button?

the xxx_tag helpers generate the appropriate input tags, so submit tag
is input type=submit, textfield_tag is a textfield etc.

Why is the do%> and <% end %> part needed? Is this saying do the
following ruby code?

form_tag / remote_form_tag take a block - the do/end are just the
block delimiters

The difference between the two seconds, as the book explains, is that
the second sends an AJAX request instead of a POST request. I read
that, I think I understand it, but I don’t exactly know why there is a
difference. Can someone explain?

AJAX is a big topic in itself but the key difference is that whereas a
‘normal’ request reloads the whole page, an AJAX request just happens
in the background and you get to decide how the response from the
server is used.

Fred