100_mini_posts - Curious Dev

Active Record includes and N + 1 Query Problem

Consider the following code books = Book.limit(10) books.each do |book| puts book.author.last_name end In the above code, a query is made each time the lastname of an author of a book is needed in puts book.author.last_name. A single query for each book.

rails

How to Use Enums in Rails Active Record

Suppose you're making a book tracking app to keep a log of all the books you consume. And you want to log the format. As in, was it an ebook, an audiobook or was it an actual physical paper copy? You would create a column named format on your model.

rails

Rails Console Commands Cheatsheet

Rails console is useful playground for trying out various view helper commands as well as experimenting with our Active Record data model. Here is a rundown of some of the things we can do with in a Rails console session. Basic commands Reloading the Console We can enter the Rails

rails

Active Record Association Advanced Topics

What are polymorphic associations? When do we need to create join tables? When do we use single table inheritence? We will cover some more advanced topics with Active Record Associations in this post. Note: This post assumes that you are already familiar with common Active Record associations. You can see

rails

Rails Active Record Association Basics

In Rails, an association is a connection between two Active Record models. With associations we get convenient utility methods to easily query and do operations on those models. Rails has the following associations belongs_to, has_many, has_one, has_one :through, has_many :through, has_and_belongs_to_many

ruby

Ruby Metaprogramming Part 2

We continue with more reflection methods in Ruby like instance_variables, local_variables, constants for variables and public_methods, private_methods, method_definded? for methods. Note: This is part 2 of metaprogramming in Ruby, in part 1 we covered evaluating strings and blocks with instance_eval and such. Reflection Methods

ruby

Ruby Metaprogramming Part 1

define_method, Kernel.eval, instance_method, instance_eval, class_eval, instance_exec, send, bind. Have you seen Ruby programs with these methods or haven't been sure what each of them do exactly? By the end of this post you will be able to confidently read Ruby code that contains these

ruby

Ruby Method Object, define_method and bind

Ruby methods are executable language constructs. They are not objects. But we can get objects that represents methods with the Object class's method method. Note: This is similar to how blocks are language syntax but not objects in Ruby and we can get object versions of blocks in the forms

ruby

Difference Between Ruby Blocks, Procs, and Lambdas

If you're new to Ruby or if you've been using Ruby for a while but want to understand procs and lambdas a bit deeper, this post is for you. We will look at the Proc object, four ways to create procs and lambdas, see how to invoke them, and look

ruby

How &: Works in Ruby

Chances are you've seen and written code like users.map(&:first_name) in ruby or rails applications many times. And you may have wondered is that & an operator, is that : part of a Symbol. It's a strange syntax. Let's demysify &: so you'll know how to use it

sql

What is Arel: Between ActiveRecord and SQL Queries

I recently heard that ActiveRecord uses Arel under the hood. What is Arel? When would it be useful in practice? Whenever I hear the phrase under-the-hood I get excited. I want to know EVERYTHING. So let's find out! Motivation ActiveRecord is useful and its DSL allows us to write many