Rails - Oct 2007 - Custom method in Application Controller

Hi All,

I took this idea Christian Hellsten and Jarkko Laine''s "Beginning
Ruby
on Rails E-Commerce".

Here is the situation.  I will be using the
"options_from_collection_for_select" and "collection_select"
form helper
methods in my view to render drop-down selection lists for City and
State that have corresponding city_id and state_id foreign key
references in my address model/table.

In Chapter 3 of this book, the authors suggesting using a private method
in the address controller (contrived) called "load_data" which looks
something like this:

def load_data
@cities = City.find(:all)
@states = State.find(:all)
end

This method initializes and loads the @cities and @states instances
variables with a hash of all the cities and all the states in their
respective tables.

e.g:
@cities = {:id => 1, :name => "City Name"}

then, the method is called in the "new", "edit" and
"create" methods of
the address controller like so...

def new
load_data
@address = Address.new
end

def create
@address = Address.new(params[:address])
if @address.save
flash[:notice] = "Address was successfully saved"
redirect_to :action => :list
else
load_data
render :action => :new
end

but, what I would like to do refactor this by moving this method to the
application controller and add parameters to the "load_data" method to
preferentially select the model so that I may use this method in other
models that have nothing to do with the City or State models and I had
hoped it would look something like this:

def load_data(model)
@model.pluralize = Model.find(:all)
end

and I call the method like so:

AddressesController<<ApplicationController

def new
load_data(:City)
load_data(:State)
@address = Address.new
end

but I get a localjumperror exception thrown in the "new" method in the
Address controller with the error message "no block given"

does any one have any idea on how to rewrite this method so that I can
call it from any controller and initialize a hash that references the
model I pass as a parameter

Thanks,

Mike
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> Here is the situation.  I will be using the
> "options_from_collection_for_select" and
"collection_select" form helper
> methods in my view to render drop-down selection lists for City and
> State that have corresponding city_id and state_id foreign key
> references in my address model/table.
>
> In Chapter 3 of this book, the authors suggesting using a private method
> in the address controller (contrived) called "load_data" which
looks
> something like this:
>
> def load_data
> @cities = City.find(:all)
> @states = State.find(:all)
> end
>
> This method initializes and loads the @cities and @states instances
> variables with a hash of all the cities and all the states in their
> respective tables.
>
> e.g:
> @cities = {:id => 1, :name => "City Name"}
>
> then, the method is called in the "new", "edit" and
"create" methods of
> the address controller like so...
>
> def new
> load_data
> @address = Address.new
> end
>
> def create
> @address = Address.new(params[:address])
> if @address.save
> flash[:notice] = "Address was successfully saved"
> redirect_to :action => :list
> else
> load_data
> render :action => :new
> end
>
> but, what I would like to do refactor this by moving this method to the
> application controller and add parameters to the "load_data"
method to
> preferentially select the model so that I may use this method in other
> models that have nothing to do with the City or State models and I had
> hoped it would look something like this:
>
> def load_data(model)
> @model.pluralize = Model.find(:all)
> end
>
> and I call the method like so:
>
> AddressesController<<ApplicationController
>
> def new
> load_data(:City)
> load_data(:State)
> @address = Address.new
> end
>
> but I get a localjumperror exception thrown in the "new" method
in the
> Address controller with the error message "no block given"
>
> does any one have any idea on how to rewrite this method so that I can
> call it from any controller and initialize a hash that references the
> model I pass as a parameter
Something like this:

def load_data(model)
   instance_variable_set(model.to_s.pluralize.to_sym,
                         const_get(model).find(:all)
end

Should do it.  I haven''t tried it though, but something along those
lines.
If I were you I''d call it using lowercase symbols though.  That way
you''ll
end up with @cities and @states.

-philip

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