Search for multiple possible param values - sql

Question

At the moment I have a form in which the user can input price per person and/or duration and/or team_size. What I would like to accomplish is to retrieve all records from a table that match the user input and for this I set scope in the model:
scope :filter_by_team_size, -> (team_size) { where("team_size = ?", team_size) }
scope :filter_by_duration, -> (duration) { where("duration = ?", duration) }
scope :filter_by_price, -> (price) { where("price = ?", price) }
And then in the controller use that again to retrieve the records by doing so:
#experiences = policy_scope(Experience).order(team_size: :desc).geocoded.filter_by_team_size(params[:team_size]) if params[:team_size].present?
#experiences = policy_scope(Experience).order(duration: :desc).geocoded.filter_by_duration(params[:duration]) if params[:duration].present?
#experiences = policy_scope(Experience).order(price: :desc).geocoded.filter_by_price(params[:price]) if params[:price].present?
However, this only gives me only the records for which the first input value matches but ignores all other values. Additionally, when you are viewing the search results and use the filter again it should apply the filter only for the records it found already.
Any suggestion on how to solve this would be much appreciated!

Answer 1

One way to handle this is to use a virtual model that handles binding parameters to and from the form:
class SearchQuery
include ActiveModel::Model
include ActiveModel::Attributes
attribute :team_size, :integer
attribute :duration
attribute :price
end
You can then setup the form:
<%= form_with(model: (#search_query || SearchQuery.new), url: '/experiences', method: :get) %>
<div>
<%= f.label :team_size %>
<%= f.number_field :team_size %>
</div>
# ..
<% end %>
And then you can just bind the params to the model with ActionController::Parameters#permit just like you would with a normal ActiveRecord model:
class ExperiencesController
before_action :set_search_query, only: :index, if: ->{ params[:search_query].present? }
# ...
def index
#experiences = if #search_query
#search_query.build_scope(policy_scope(Experience))
else
policy_scope(Experience)
end.geocoded
end
private
def set_search_query
#search_query = SearchQuery.new(search_query_params)
end
def search_query_params
params.fetch(:search_query).permit(:team_size, :duration, :price)
end
end
This loopback will make the form stateful just like your normal CRUD forms. We have not actually implemented #build_scope yes so lets do so:
class SearchQuery
include ActiveModel::Model
include ActiveModel::Attributes
attribute :team_size, :integer
attribute :duration
attribute :price
def build_scope(base_scope)
compacted_attributes = attributes.reject { value.nil? || value.empty? }
compacted_attributes.each_with_object(base_scope) do |(k,v), base|
if base.respond_to? "filter_by_#{k}"
# lets you customize the logic with a scope
base.send("filter_by_#{k}", v) # the scope is responsible for ordering
else
# convention over configuration!
base.where(Hash[k,v]).order(Hash[k,:desc])
end
end
end
end
Since this uses convention over configuration you can get rid of those pointless scopes in your model.