On Sep 19, 8:40 pm, andrew <[email protected]> wrote:
> Greetings,
>
> I'm new to Ruby on Rails. I'm working through "Agile Web Development
> 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:
>
> <!-- START:add_to_cart -->
> <%= button_to "Add to Cart", :action => 'add_to_cart', :id => product
> %>
> <!-- END:add_to_cart -->
>
> With this:
>
> <!-- START:form_remote_tag -->
> <% 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?
>
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
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