Advantage of using find_each and find_in_batches in rails

Usually when we want to loop through all rows of an active record model, we do User.all.each { |user| user.update_role } But when we do this in Rails console, it loads all the User objects in to memory and performs the action. Performance of the application will go down if number of users is more. To […]

How to show Google Analytics dashboard in a Ruby on Rails application?

I was researching on importing GA dashboard in my rails application. Putting together steps involved in it and the reference links here 1. Understand Google Analytics dimensions and metrics Reference Links Google Analytics metrics and dimensions Difference between dimensions and metrics Google Spreadsheet which has list of dimensions and metrics GA API tool – This […]

Difference between Module and a Class in Ruby

Ruby modules can have number of methods inside. But objects cannot be instantiated from a module. Module can hold only behaviors but a class can hold behaviors and states. To use the methods defined in a module, the module should be included inside a class and the module methods can be called by using the […]

splat operator in Ruby

Arraying your arguments The list of parameters passed to an object is, in fact, available as a list. To do this, we use what is called the splat operator – which is just an asterisk (*). The splat operator is used to handle methods which have a variable parameter list. Let’s use it to create […]

Skipping Active Record validations in Rails

1. Skipping all validations written in the model. This can be achieved by passing validate: false for save /create method E.g. @book.save(validate: false) 2. Skipping individual validations First we need to create a property on our model called something like skip_name_validation attr_accessor :skip_name_validation, :skip_price_validation Next we will tell Rails to check and see if that […]

Mysql self left join

I have the following employee table Emp ID Month Salary 1000 Aug 35000 1001 Aug 45000 1002 Aug 60000 1000 Sep 37000 1001 Sep 46000 Query to fetch the salary details of employees for August and September month in a single row select e1.emp_id,e1.salary as august_month_salary,e2.salary as september_month_salary from employees e1 left join (select […]

Run Mysql procedure in background

I wanted to send messages to 1 lakh 20k users of our social networking platform in a short span of time. Found a way to run mysql procedure as background process. It helped me in inserting all the records in few seconds. Step 1: Have written the stored procedure – broadcast_message() to insert into our […]

save all existing records in rails

In an existing application, I am adding gem Friendly ID to generate slug for User model. I was looking for a simple way to update slug for all the existing records. The following is the simple solution to be run in rails console to generate slug for all records in users table. User.find_each(&:save)

Ubuntu: Find and Replace in multiple files using a single command.

I was working on upgrading our rails project. I had to change the text “named_scope” to “scope” in the all the files. The following command helped me… 🙂 find * -exec sed -i “s/named_scope/scope/g” {} \;

How to use Workling in Rails to increase the speed of the request processing

In ruby on rails application, if your request is taking too much time to process, you can make some part of the code to run in background. For example, In my application , I am sending notifications to owner,watch listers and trackers of a post, if there is any activity on the post. So when […]

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