query single dropdown menu with multiple dropdown menus via rails - sql

Question

I'm having some difficulty figuring out the following problem. I apologize if this writeup is slightly confusing, but I'll try to explain it as best as I can.
I'm relatively new to rails, and I'm trying to implement a query on my site. One portion of my site allows users to select a State from a dropdown menu when filling out a form.
Another portion of the site, (the portion that implements the query) allows users to query for a form based on the State associated with it. The page is essentially only 4 dropdown boxes, and a submit button. This query should allow users to find forms from multiple States by selecting the desired States from the available dropdown menus. Meaning a user can query for forms from 4 different states, and it would return all forms where the state on the form matches the state from one of the four dropdown menus.
So, a user can select "Georgia" from state_1 (name of dropdown), "Texas" from state_2, "California" from state_3, and "Ohio" from state_4. Once a user submits their search, I would like to return all the forms available that match the user's dropdown selections.
I'm running into some issues at present. here is the code I currently have:
def self.search(params)
form = self.scoped
form = form.where(:state => params[:state_1]) if params[:state_1].present?
form = form.where(:state => params[:state_2]) if params[:state_2].present?
form = form.where(:state => params[:state_3]) if params[:state_3].present?
form = form.where(:state => params[:state_4]) if params[:state_4].present?
form
end
The issue i am running into is the following: If I run a query with only a selection on state_1, then it returns all of the fields associated with that state (which is excellent); however, if I try to run a query with selections on multiple dropdown menus (for example, "Georgia" on state_1 and "Texas" on state_2) no forms are returned.
Again, I sincerely apologize if this is confusing, and I'm grateful for your time. I would appreciate any help and I'll do my best to respond to any questions as prompt as possible. Thank you so much!

Answer 1

If you have both :state_1 and :state_2 set, then you'll be doing this:
form = form.where(:state => params[:state_1]).where(state => params[:state_2])
And that's saying
state = 'TX' AND state = 'GA'
Each time you call .where, you're appending another condition with a conjunction (i.e. AND). I think you're after this:
states = [:state_1, :state_2, :state_3, :state_4].map { |k| params[k] }.reject(&:blank?)
form = form.where(:state => states) if(!states.empty?)
That will turn into SQL sort of like this:
state IN ('TX', 'GA')
and that seems to be what you're after. The map will extract the param values with for the specified state keys and then the reject will filter out the blank ones (i.e. false, nil, empty, or all whitespace).