Stored Procedures and Rails – Part 1


There is no documentation in Rails about how to use stored procedures or atleast it is difficult to find where to look at. And according to DHH stored procedures is not the Rails Way to do things. DHH mentioned in his post

I want a single layer of cleverness: My domain model. Object-orientation is all about encapsulating clever. Letting it sieve half ways through to the database is a terrible violation of those fine intentions. And I want no part of it.

I somewhat agree to what DHH has to say. And that’s all fine but what if we don’t have any other option apart from using stored procedure and our stored procedure has some complex logic which we don’t want to put in our Ruby code then here is a little hack to it

ActiveRecord::Base.connection.execute("execute procedure_name")

But the above code will not return anything it will only execute your procedure, considering everything went OK.

Moreover, it’s not DRY if everytime you have to write that line of code just to call a procedure.

Here is a better way to do it:

1) Create a class and let’s call it

Class DbStoredProcedure
  your methods here .......
end

2) Create a class method within it

def self.fetch_db_records(proc_name_with_parameters)
  ActiveRecord::Base.connection.execute(proc_name_with_parameters)
end

Then simply call it as

DbStoredProcedure.fetch_db_records("exec procedure_name 'args1', 'args2', 'and so on' ")

As mentioned above, this will only execute a procedure without returning any value. To return records or values from stored procedures can use other methods provided by the AR,

class DbStoredProcedure < ActiveRecord::Base

  def self.fetch_db_records(proc_name_with_parameters)
    connection.select_all(proc_name_with_parameters)
  end

  def self.insert_update_delete_calculate(proc_name_with_parameters)
    connection.execute(proc_name_with_parameters)
  end

  def self.fetch_val_from_sp(proc_name_with_parameters)
    connection.select_value(proc_name_with_parameters)
  end

end

And then simply call it like

DbStoredProcedure.method_name("exec procedure_name 'args1', 'args2', 'and so on' ")

Sweet…

If you know a better way to do it then I would love to know your views.

Stored Procedures and Rails – Part 2

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13 thoughts on “Stored Procedures and Rails – Part 1

  1. Sofija says:

    Thank you! It is a really great to be able to find some solution when there is no core solution.

    Anyway, for RoR to be able to be an enterprise class programming language and framework using stored procedures and views in an database should be part of core.
    I’m not sure if there are RoR developers that are aware that procedures are best way to implement database logic, except for maybe some trivial models. That’s why I believe using stored procedures should be supported by core ActiveRecord and defined per each available datrabase adapter to support different usages. One ExecProc! should do it…
    Also did anyone notice availability explicit of START TRANSACTION END TRANSACTION implementations? These are like crucial for any serious developement.

  2. Suset Fernandez says:

    I am triying to call my stored procedures using the class CallStoredProcedures as you did suggest but it does not work. Can I have an example please?.

  3. nasir says:

    @Suset could you please give some more information on

    1. what exactly you tried,

    2. why do you think it is not working,

    3. which db you are using, and

    4. any other information or errors, etc.

    • Suset Fernandez says:

      1. what exactly you tried,

      I need to call a postgre stored procedure i did program some time ago, so I copied the code you suggets before.
      I created the class DbStoredProcedure

      2. why do you think it is not working,

      When I call any method of the class it does not return anything or show any error, simply nothing happens

      3. which db you are using, and

      Postgres

      4. any other information or errors, etc.

      I am totally “new” using Ruby on Rails
      I think I need a functional example, to understand better.

  4. Petrus says:

    Tried it & ditto the same error, jruby thinks I am trying to do an update. I tried to add the code on an existing model. It just does not work.

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