Specific search implementation - ruby-on-rails

Question

So I'm trying to improve the search feature for my app
My model relationships/associations are like so (many>one, one=one):
Clients < Projects < Activities = Assignments = Users
Assignments < Tasks
Tasks table has only a foreign key to assignments.
Search params look something like this:
params[:search]==User: 'user_handle', Client: 'client_name', Project: 'project_name', Activity: 'activity_name'
So I need to porbably search Clients.where().tasks, Projects.where().tasks and so on.
Then I need to somehow concatenate those queries and get rid of all the duplicate results. How to do that in practice however, I have no clue.
I've been hitting my head against a brick wall with this and internet searches didn't really help... so any help is greatly apreciated. Its probably a simple solution too...
I am on rails 4.2.5 sqlite for dev pg for production

Answer 1

A few things I would change/recommend based on the code in your own answer:
Move the search queries into scopes on each model class
Prefer AREL over raw SQL when composing queries (here's a quick
guide)
Enhance rails to use some sort of or when querying Models
The changes I suggest will enable you to do something like this:
search = search_params
tasks = Tasks.all
tasks = tasks.or.user_handle_matches(handle) if (handle = search[:user].presence)
tasks = tasks.or.client_name_matches(name) if (name = search[:client].presence)
tasks = tasks.or.project_name_matches(name) if (name = search[:project].presence)
tasks = tasks.or.activity_name_matches(name) if (name = search[:activity].presence)
#tasks = tasks.uniq
First, convert each of your queries to a scope on your models. This enables you to reuse your scopes later:
class User
scope :handle_matches, ->(handle) {
where(arel_table[:handle].matches("%#{handle}%"))
}
end
class Client
scope :name_matches, ->(name) {
where(arel_table[:name].matches("%#{name}%"))
}
end
class Project
scope :name_matches, ->(name) {
where(arel_table[:name].matches("%#{name}%"))
}
end
class Activity
scope :name_matches, ->(name) {
where(arel_table[:name].matches("%#{name}%"))
}
end
You can then use these scopes on your Task model to allow for better searching capabilities. For each of the scopes on Task we are doing an join (inner join) on a relationship and using the scope to limit the results of the join:
class Task
belongs_to :assignment
has_one :user, :through => :assignment
has_one :activity, :through => :assignment
has_one :project, :through => :activity
scope :user_handle_matches, ->(handle) {
joins(:user).merge( User.handle_matches(handle) )
}
scope :client_name_matches, ->(name) {
joins(:client).merge( Client.name_matches(name) )
}
scope :activity_name_matches, ->(name) {
joins(:activity).merge( Activity.name_matches(name) )
}
scope :project_name_matches, ->(name) {
joins(:project).merge( Project.name_matches(name) )
}
end
The final problem to solve is oring the results. Rails 4 and below don't really allow this out of the box but there are gems and code out there to allow this functionality.
I often include the code in this GitHub gist in an initializer to allow oring of scopes. The code allows you to do things like Person.where(name: 'John').or.where(name: 'Jane').
Many other options are discussed in this SO question.
If you don't want include random code and gems, another option is to pass an array of ids into the where clause. This generates a query similar to SELECT * FROM tasks WHERE id IN (1, 4, 5, ...):
tasks = []
tasks << Tasks.user_handle_matches(handle) if (handle = search[:user].presence)
tasks << tasks.or.client_name_matches(name) if (name = search[:client].presence)
tasks << tasks.or.project_name_matches(name) if (name = search[:project].presence)
tasks << tasks.or.activity_name_matches(name) if (name = search[:activity].presence)
# get the matching id's for each query defined above
# this is the catch, each call to `pluck` is another hit of the db
task_ids = tasks.collect {|query| query.pluck(:id) }
tasks_ids.uniq!
#tasks = Tasks.where(id: tasks_ids)

Answer 2

So I solved it, it is supper sloppy however.
first I wrote a method
def add_res(ar_obj)
ar_obj.each do |o|
res += o.tasks
end
return res
end
then I wrote my search logic like so
if !search_params[:user].empty?
query = add_res(User.where('handle LIKE ?', "%#{search_params[:user]}%"))
#tasks.nil? ? #tasks=query : #tasks=#tasks&query
end
if !search_params[:client].empty?
query = add_res(Client.where('name LIKE ?', "%#{search_params[:client]}%"))
#tasks.nil? ? #tasks=query : #tasks=#tasks&query
end
if !search_params[:project].empty?
query = add_res(Project.where('name LIKE ?', "%#{search_params[:project]}%"))
#tasks.nil? ? #tasks=query : #tasks=#tasks&query
end
if !search_params[:activity].empty?
query = add_res(Activity.where('name LIKE ?', "%#{search_params[:activity]}%"))
#tasks.nil? ? #tasks=query : #tasks=#tasks&query
end
if #tasks.nil?
#tasks=Task.all
end
#tasks=#tasks.uniq
If someone can provide a better answer I would be forever greatful