[Rubycocoa-talk] Using ActiveRecord from RubyCocoa (was Re: Rails)

[Tim B. <tim...@gm...>]

On Sep 1, 2006, at 1:28 AM, Eloy Duran wrote:
> I'm very interested to hear about it too....
>
> I think you should take a look at:
> http://wiki.rubyonrails.com/rails/pages/HowToUseActiveRecordOutsideRails
>
> On 9/1/06, Jonathan Paisley <jp...@dc...> wrote:
>> On Thu, 24 Aug 2006 5:54pm +0200, Cornelius Jaeger wrote:
>>
>>> Has anyone played with using rails as a backend to rubycocoa.
>>> i know there is coredata, which i love, but it would allow cross
>>> platform development of business objects and db access /  
>>> abstraction.
>>> Has anyone got an example?
>>
>> Are you talking about using ActiveRecord (a component of rails) as  
>> a data
>> storage mechanism for a RubyCocoa application?
>>
>> I've not tried it. But I'd be interested to hear of how it works out.

I've done this.  Here are some code excerpts from a program that  
displays ActiveRecord objects in NSTableViews. The key element is the  
ArrayTableModel class; it implements the data source protocol for the  
table view.

class ArrayTableModel < OSX::NSObject
   attr_accessor :array
   def initWithArray(array)
     @array = array
     self
   end
   def numberOfRowsInTableView(view)
     @array.length
   end
   def tableView_objectValueForTableColumn_row(view,column,row)
     @array[row].send(column.identifier.to_s).to_s
   end
   def tableView_shouldEditTableColumn_row(view,column,row)
     false
   end
end

Once you've created an instance of your model, you can  
programmatically create and configure a table view like this:

def tv(columns, model)
   view = TableView.alloc.initWithFrame([0,0,500,200])
   view.setAutoresizingMask(OSX::NSViewWidthSizable +  
OSX::NSViewHeightSizable)
   view.setColumns columns
   view.setDelegate model
   view.setDataSource model
   view
end

Here's the top-level code, which uses the Quote class (a subclass of  
ActiveRecord) to look up price quotes from a MySQL database.  The  
column names/identifiers are simply fields in the database which the  
data source sends to ActiveRecord objects as messages.

def tableview(symbol = "AAPL", daterange=nil)
   quotes = Quote.find_all_by_symbol(symbol).sort_by{|ed| -ed.date.to_i}
   tv(['date', 'open', 'last', 'high', 'low', 'volume'],  
ArrayTableModel.alloc.initWithArray(quotes))
end

You'll have to put this somewhere in your code to connect to the  
database:

ActiveRecord::Base.establish_connection(
	:adapter => "mysql",
	:host => "localhost",
	:username => "my-username",
	:password => "my-password",
	:database => "my-database"
)

It's easy, but watch out for name conflicts.  ActiveRecord defines a  
lot of messages.  Some of them have names that might conflict with  
message names on the Objective-C side of your project, meaning that  
you'll have to use the "oc_" prefix to call those Objective-C methods  
from Ruby.

Tim