Squeel and rails ... dynamic where clause

Question

Squeel and rails ... dynamic where clause

Using Squeel, in a rails app, I have a conditions hash:

{'trans' => 'manual'}

which I end up planning on going into an array ... so I can also have an operator assignment.

[[field,operator,value][field,operator,value]]

I want to use the Model method, which at the moment I am omitting the operator, and I am just trying to do this to get this to work ... however what I have below does not work.

def self.with_conditions(conditions)
    joins{car}.where do
      conditions.map {|key,value| (key==value) }.inject(:&)
    end
end

I also tried this:

def self.with_conditions(conditions)
  joins{car}.where do
    query = nil

    conditions.each do |key, value|
      q = (key == value)

      if query
        query &= q
      else
        query = q
      end
    end

    query     
  end
end

So how can I get this to work with the == parameter, and then how do I end up getting this to work with the dynamic operator? thank

In the console, my SQL is not readable in any of my conditions ... for example:

in the console:

> Timeslip.with_conditions({'car.year'=>'1991'})

SELECT "timeslips".* FROM "timeslips" INNER JOIN "cars" ON "cars"."id" = "timeslips"."car_id"

+3

ruby-on-rails ruby-on-rails-3 squeel

Joel grannas 01 Feb 13 at 19:56

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2 answers

deefour · Answer 1 · 2013-02-01T20:21:14+0000

You need to programmatically build your Squeel query. For example:

def self.with_conditions(conditions)
  conditions.map do |col, str|
    Squeel::Nodes::Predicate.new(Squeel::Nodes::Stub.new(col), :matches, str) # (email.matches "user@example.com")
  end.inject do |t, expr|
    t & expr # joins each expression from the .map above with & - to be converted to AND in the sql
  end.tap do |block|
    return where{(block)} # pass the constructed expression to Squeel
  end
end

In my model, User::User

I can run

User::User.with_conditions({email: "user@example.com", first_name: "Deefour"}).to_sql

and i will get

SELECT "user_users".* FROM "user_users"  WHERE (("user_users"."email" LIKE 'user@example.com' AND "user_users"."first_name" LIKE 'Deefour'))

orourkedd · Answer 2 · 2014-01-03T12:12:32+0000

I don't know if it helps, but I did it like this using this helper method:

  def query_for_matches(key, value)
    stub = Squeel::Nodes::Stub.new(key)
    Squeel::Nodes::Predicate.new(stub, :matches, "%#{value}%")
  end

You have a hash of parameters from a request for something:

  dynamic_params = {'username' => 'some_name', 'email' => 'email@example.com'}

Then I use this with chaining where

in a loop:

  query = SomeModel #could be User, etc
  dynamic_params.each_pair {|key,value| query = query.where(query_for_matches(key, value)) }

Then you can transfer query

to your view or whatever. I've only been on the rails for a couple of weeks, so not sure if this is the best practice, but it works.

Squeel and rails ... dynamic where clause

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