DRY and Elegant way to represent all search combinations without growing exponentially? - ruby-on-rails

Question

Right now I can search the following
1) leaving_from location
2) going_to location
3) leaving_from &
going_to location
if params[:leaving_from].present? && params[:going_to].present?
#flights = Flight.where(:source => params[:leaving_from]).where(:destination => params[:going_to])
elsif params[:leaving_from].present?
#flights = Flight.where(:source => params[:leaving_from])
elsif params[:going_to].present?
#flights = Flight.where(:destination => params[:going_to])
end
Is there a dry way to represent this code above? Basically its a for search function compromised of 2 drop down search boxes. One for leaving from location and another for going to location. With the option of narrowing it down by both locations or just one location.
It works fine now but it isn't very scalable. If I added more search parameters say price and time, it would grow exponentially in order to be able to represent all the states.
For example if I added price my new combinations would be
1) leaving_from location
2) going_to location
3) leaving_from &
going_to location
4) price
5) leaving_from location & price
6) going_to location & price
7) leaving_from location & going_to location & price
I need help to figure out a better way to represent this, or else it would make my controller incredibly bloated.
EDIT FORM CODE --
=form_tag '/flights', :method => :get
%h4
Leaving From:
=select_tag 'leaving_from', content_tag(:option,'select one...',:value=>"")+options_for_select(#flights_source, 'source'), { :class => 'form-control' }
%h4
Going To:
=select_tag 'going_to', content_tag(:option,'select one...',:value=>"")+options_for_select(#flights_destination, 'destination'), { :class => 'form-control' }
%h4=submit_tag "Search", :name => nil, :class => 'btn btn-success btn-md btn-block'

Answer 1

In place of using leaving_from or going_to use source and destination instead and Move all the required parameters under a key, e.g., this solution will work for any no. of keys
'required' => { 'source' => value, 'destination' => value, 'price' => value }
Now in the controller define this method in private
def get_flights(params)
possible_combination = []
conditions = {}
key_array = params['required'].keys
1.upto(key_array.length) { |i| possible_combination + key_array.combination(i).to_a }
possible_combination.reverse.each do |comb|
if comb.collect{ |key| params['required'][key].present? }.inject(:&)
comb.map { |key| conditions[key] = params['required'][key] }
break
end
end
Flight.where(conditions)
end
Call this method from any action
#flights = get_flights(params)
Hope this works! Its an overall idea to make this thing dynamic, you can refactor the code according to your need!

Answer 2

First things first: your code does not do what you think it does, since there is no way for it to execute the third if (every time the third if is true, the first if is as well). On to your question:
#flights = Flight
#flights = #flights.where(:source => params[:leaving_from]) if params[:leaving_from].present?
#flights = #flights.where(:destination => params[:going_to]) if params[:going_to].present?
Or
conditions = {}
conditions[:source] = params[:leaving_from] if params[:leaving_from].present?
conditions[:destination] = params[:going_to] if params[:going_to].present?
#flights = Flight.where(conditions)

Answer 3

How about using ransack which adds your rails to search function very easily.
You just write below, if you use ransack.
# View (Search Form)
<%= search_form_for #q do |f| %>
From: <%= f.text_field :leaving_from_cont %>
To : <%= f.text_field :going_to_cont %>
Price:
<%= f.text_field :price_gteq %> 〜 <%= f.text_field :price_lteq %>
<%= f.submit %>
<% end %>
# Controller
def index
#q = Flight.ransack(parmas[:q])
#flights = #q.result(distinct: true)
end
If a user don't input any fields, ransack don't use the non-input fields value. It means don't add WHERE conditions in DB.
column_name_cont means contain (Like in DB).
column_name_eq means equal (== in DB).
column_name_gteq means greater than equal (<= in DB).
column_name_lteq means less than equal (>= in DB).
etc...
Also you can sort the search result easily by using sort_link methods of ransack.
Please look in ransack.

Answer 4

I was not able to get #RSB's code to work but I was able to use his example to create a method that did work. I call the below code in my action.
#flights = get_flights(search_params)
The search_params method is as follows:
def search_params
params.permit(:leaving_from, :going_to)
params_hash = {'required' => { 'source' => params[:leaving_from], 'destination' => params[:going_to]}}
end
And finally the get_flights method is:
def get_flights(params)
possible_combination = []
conditions = {}
key_array = params['required'].keys
possible_combination = (possible_combination + key_array.combination(key_array.length).to_a).flatten
possible_combination.each do |comb|
conditions[comb] = params['required'][comb] if params['required'][comb].present?
end
Flight.where(conditions)
end
I am still pretty new to ruby and rails so any feedback or suggestions for improvements would be greatly welcome. Thanks!