Store data retrieved as result of find_by_sql method in ruby on rails

Question

I am new to ruby on rails. I am trying to retrieve data from my database and make operation in my rails application. I am stuck while trying to use find_by_sql in my class Activity < ActiveRecord::Base

I have a rates table with structure as

id | Instrument Name | Category | Time_of_usage | Rates
1  | Instrument1     | Internal | Regular       | 25
2  | Instrument2     | Internal | Weekends      | 15  

Here is my sample code of what I am trying to achieve

sql2='SELECT Rates FROM New_billcodes_mock WHERE Category_name=?, Instrument_name=? and Time_zone_name=?'
result2=  find_by_sql[sql2,'Internal','Instrument1',time_zone_name]
database_billrate_value_normal=result2['Rates']

and use the database_billrate_value_normal variable to make my operations.

Please guide me in the correct path if I am wrong.

Answer 1

I'm unclear if the model with the rate table is Activity or NewBillcodeMock or Rate.

If it is Rate, you should be able to do something like this:

database_billrate_value_normal = 
    Rate.where("category_name=? AND 
                instrument_name=? AND 
                time_zone_name=?",
                params[:category_name],
                params[:instrument_name],
                params[:time_zone_name]).pluck[:rates]

... assuming you have a hash params with the required attribute values those are the actual attribute names.

This will return an array of rates which you can then manipulate directly in Ruby as needed.