Ajax in Rails

rubyonrails-talk
1

Hi All,

New to the group, and new to learning rails.

I'm having some trouble, i've done a few tutorials on creating some small apps with rails and am now starting to play around myself.

I've been trying to create a simple form which when a user enters any data that data is displayed as a preview elsewhere on the page instantly, just like when creating an advert with Google Adwords, the preview is shown.

I've been using form_remote_for and observe_form but I don't seem to be having much luck at all. I am unsure how to use the controller to get the form fields and pass them back to a partial to be rendered?

Here is my form:

<% form_remote_for @advert do |a| %> <label>Title:</label> <%= a.text_field :title %> <br /> <label>First Line:</label> <%= a.text_field :first_line %> <br /> <label>Second Line:</label> <%= a.text_field :second_line %> <br /> <label>Visible URL:</label> <%= a.text_field :visible_url %> <br /> <label>Destination URL:</label> <%= a.text_field :destination_url %> <%= submit_tag 'Submit' %> <% end %>

Any help would be great?

Cheers,

Phil

2

I've been trying to create a simple form which when a user enters any data that data is displayed as a preview elsewhere on the page instantly, just like when creating an advert with Google Adwords, the preview is shown.

I've been using form_remote_for and observe_form but I don't seem to be having much luck at all. I am unsure how to use the controller to get the form fields and pass them back to a partial to be rendered?

In this respect it's much like a normal form, eg the title will be params[:advert][:title] (assuming @advert is of class Advert). As usual you can just looking at development.log to see what the parameters look like.

Fred

3

So then do I need to use the controller to populate another @advert object with all the params then render the partial?

Cheers,

Phil

4

So then do I need to use the controller to populate another @advert object with all the params then render the partial?

Well I don't know exactly what this controller is trying to do at all. Assuming what it's doing is create a new object then the controller code is almost exactly the same as a regular create action, the only difference is that instead of redirecting to the show action you're rendering a partial for the object you've just created.

Fred

5

I am simply trying to show what the user enters somewhere else on the page as they type it.

I did get it to work using render :text => param[:advert][:title] + '<br/>' + param[:advert][:first_line] ......

But I think there should be a more efficient way to do it?

Could I do something like this:

def preview   @advert = Advert.new(params[:advert])   render :partial => 'advert' end

Phil

6

I am simply trying to show what the user enters somewhere else on the page as they type it.

I did get it to work using render :text => param[:advert][:title] + '<br/>' + param[:advert][:first_line] ......

But I think there should be a more efficient way to do it?

Could I do something like this:

def preview @advert = Advert.new(params[:advert]) render :partial => 'advert' end

Something like that is fine (although you'll need to tell rails to use the @advert object). It's not more efficient in terms of raw cpu cycles but I'm assuming that's not what you meant (it is a lot easier on the eye and a better separation of presentation from your actual code).

Fred

7

Thanks Fred,

How would I then need to tell rails to use the @advert object because that's the part that I have been having trouble with?

Phil

8

phil7085 wrote:

How would I then need to tell rails to use the @advert object because that's the part that I have been having trouble with?

Formerly, it was this:

  def preview     @advert = Advert.new(params[:advert])     render :partial => 'advert', :locals =>{ :@advert => @advert }   end

I prefer that style because it makes @advert, inside the partial, safe to test for nil. However, on our latest new project (Rails 2.2.2) either we did something else wrong, or the :@ stopped working, and we had to use this:

    render :partial => 'advert', :locals =>{ :advert => @advert }

Does anyone know if the :@ trick should still work?

9

Thanks Fred,

How would I then need to tell rails to use the @advert object because that's the part that I have been having trouble with?

render :partial => 'blah', :object => foo

Fred

10

Frederick Cheung wrote:

render :partial => 'blah', :object => foo

To save me from Googling for "object", what does that look like inside the partial?

11

the object specified in that way is assigned to a local variable called object and to a local variable called after the partial (ie the same thing that happens when you do :collection => foos) (or using the name specified in the :as option)

Fred

12

Thanks,

I will give this a try, although as a newbie this talk of :locals, :object, etc has slightly gone over my head. I'm sure i'll get it.

Phil

13

Hi guys,

I've tried both of those options and can't get it to work, I think it's the way I am trying to retrieve the values in the partial.

In the development.log I have this error: undefined method `title' for #<HashWithIndifferentAccess:0x1f7f930>

In my controller I have this:

render :partial => 'advert', :object => @advert

And in my partial I have tried both if these:

<%= advert.title %> <%= @advert.title %>

No luck.

Any suggestions?

Phil

14

Ok I've got it to work by using this in my partial:

<%= @advert[:title] %>

Can you tell me why I have to reference like this?

Phil

15

Ok I've got it to work by using this in my partial:

<%= @advert[:title] %>

Can you tell me why I have to reference like this?

The errors you mentionned imply that @advert isn't actually an instance of the Advert class.

Fred

16

Ok Fred, I think I understand, I've now changed the controller to look like this:

  def preview     @advert = Advert.new(params[:advert])     render :partial => 'advert', :object => @advert   end

Before I had: @advert = params[:advert] which I think is what you mean by it not being an instance of the class.

Now in my partial I can use @advert.title and all works fine.

Thanks for all your help.

Phil