Selecting a model


#1

I have three models: Language, Country and City.

A country has a Language and a language belongs to many countries.
A country has many cities and a city belongs to a country.

When I use Active(Scaffold) and I want to edit/insert a City, I must
select a Country. Is possible that when I must select a country, in the
list of countries appear the Country + the language.

For example:

USA-English
France-French
England-English

instead of:

USA
France
England

Thanks.


#2

Sure, I assume you do a query for the countries -> @countries =
Country.find
(:all)

for starters do this
@countries = Country.find(:all, :include => ‘languages’) which will get
the
languages in the same query.

Now, in the select you have options_for_select=[array] so you have to
build
an array that looks like this [“USA -
English”,“France-French”,“England-English”,…]

I would suggest that you create a helper method

def country_options(country_array)
reponse_array = []
country_array.each do |country|
response_array << country.name + " - " + country.language.name
end
return reponse_array
end

reponse array wil now look like this [“USA -
English”,“France-French”,“England-English”,…]

so you can do <%= select_tag(:country,
options_for_select(country_options(@countries))) %> and that will give
you
the select you wanted.


#3

Hi –

On 4/26/07, Ivor P. removed_email_address@domain.invalid wrote:

Sure, I assume you do a query for the countries -> @countries =
Country.find(:all)

for starters do this
@countries = Country.find(:all, :include => ‘languages’) which will get the
languages in the same query.

Now, in the select you have options_for_select=[array] so you have to build
an array that looks like this [“USA -
English”,“France-French”,“England-English”,…]

I believe you’d actually need something like:

[ [“USA-English”, “USA”], [“France-French”, “French”], … ]

so that you’re providing both a label and a value for each option.

I would suggest that you create a helper method

def country_options(country_array)
reponse_array = []
country_array.each do |country|
response_array << country.name + " - " + country.language.name
end
return reponse_array
end

You’ve just reimplemented map :slight_smile: You can let Ruby do more of the
work (untested):

def country_options(countries)
countries.map do |country|
[country.name + ‘-’ + country.language.name, country.name]
end
end

You could also use country.id instead of country.name for the value,
which might make it slightly easier to pull the record later.

David


Upcoming Rails training by Ruby Power and Light:
Four-day Intro to Intermediate
May 8-11, 2007
Edison, NJ
http://www.rubypal.com/events/05082007


#4

Thanks David.

Yes, I should have done the [text_value,id] - forgot about that :slight_smile:

map! nice, yeah, thanks for the tip. So map creates an array populated
with
the result of the block for each element in the array that is being
mapped?
the result is then the array containing the results for each of the
original
elements.

thanks again

Ivor