Lynn's Dev Blog

Lynn's Dev Blog

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How I learned to write raw SQL

How I learned to write raw SQL

In my daily job, I mainly use Rails framework. To make code readable and maintainable, we seldom write raw SQL in the codebase. Instead, we use Rails's ActiveRecord::QueryMethods module which helps developers write beautiful queries quickly. For example, School.joins(:students).where('students.age > ?', 7).limit(100) Recently,

7 steps I usually do before I involve in a complex feature implementation

7 steps I usually do before I involve in a complex feature implementation

Before implementing a new feature, I like to make sure what problems we are going to solve, why we should solve them, and how much time we can implement this feature. Here are 7 steps I usually do before I involve in a complex feature implementation. These steps bring many

VS Code x Rubocop - ruby_executable_hooks: No such file or directory

VS Code x Rubocop - ruby_executable_hooks: No such file or directory

Environment * macOS Monterey (Version 12.1) * Ruby 2.6.6 * Ruby version manager: RVM * Editor: VS Code To Reproduce: I've installed rubocop gem in my app and add an extension ruby-rubocop in my VS Code. Open VS Code and see the warning messages below. This caused Rubocop cannot execute correctly.

TIL: What does npm uninstall do?

TIL: What does npm uninstall do?

$ npm uninstall localtunnel removed 22 packages, and audited 1 package in 126ms found 0 vulnerabilities * npm uninstall removes the package from your package.json. * npm uninstall deletes the node_modules/localtunnel directory and localtunnel's dependencies in node_modules. -------------------------------------------------------------------------------- Reference: Uninstall a Package with npm`npm uninstall` lets you uninstall

TIL: How to define a multiline string in Ruby

TIL: How to define a multiline string in Ruby

Note: The following was tested with Ruby 2.6.6 > Keyword: Heredoc What is heredoc? Heredoc [https://en.wikipedia.org/wiki/Here_document] is used for a form of multiline strings and preserves the line breaks and whitespace (including indentation) in the text. How to define a heredoc in Ruby?

TIL: How to turn on the expanded table formatting mode in PostgreSQL

TIL: How to turn on the expanded table formatting mode in PostgreSQL

Note: The following was tested with PostgreSQL 13.1 Default setting: \x off $ psql myblog_dev myblog_dev=# SELECT "users".* FROM "users" WHERE "users"."role" = 10 LIMIT 1; The output format would be: It was difficult to read the result. Turn on the expanded table formatting mode by \x on.

6 tips to ensure your rake task runs smoothly

6 tips to ensure your rake task runs smoothly

Rake is a task runner/task management tool in Ruby. You can create diverse tasks, put tasks in the Rakefile, and execute a command like rake :your_awesome_task. Your task will start running by Rake. In Ruby, you can put task code inside a file named Rakefile, rakefile, Rakefile.

How to Benchmark my code in Ruby or Rails

How to Benchmark my code in Ruby or Rails

Recently, I had a job to fix the slow code. Before diving into fixing the slow code, I used Scout APM to identify the performance bottlenecks, which helped me make sure where the slow code is. To prove the new optimization solution is faster, in addition to checking the before-after

Lessons learned from failing to access an environment variable in YMAL file

Lessons learned from failing to access an environment variable in YMAL file

Note: The following was tested with Ruby 2.6.6 / Rails 5.2.6. Situation I tried to add an environment variable in the application.yml file. # config/application.yml default: #... API_TOKEN: ABC123456 And I expected when executing ENV['API_TOKEN'] in Rails console, I would get ABC123456. But

When ORDER BY and NULL work together

When ORDER BY and NULL work together

When we would like to sort the result-set in ascending or descending, we can use ORDER BY in SQL query. In Rails, we can use order which is derived from ActiveRecord::QueryMethods. For example, Article.all.order(published_at: :desc) Let's focus on the published_at attribute now. > What will

How to use and test an AJAX request in Rails

How to use and test an AJAX request in Rails

What's AJAX? AJAX (Asynchronous Javascript and XML) is a kind of technique that can send HTTP requests and exchange data with a server by Javascript. It's an important and practical technique to enhance the user experience, especially when we want to achieve the effect that updating the partial content and

Play with nil

What's nil? nil is an instance of NilClass. It's a special Ruby object used to represent the absence of any value. And it also behaves like false when used in a conditional statement. What's more, there is only one nil object, whose object_id is always 8 (in 64-bit Ruby)

3 helpful methods in Rails console

3 helpful methods in Rails console

Recently, I start reading Practicing Rails [https://www.justinweiss.com/practicing-rails/]. I love the main point in chapter 1: Rails console is a good place to experiment with our ideas. There are 3 tips to explore ideas through the Rails console I learned from Practicing Rails. 1. Use app object.

RSpec - Use shared_examples to avoid duplicate test examples

RSpec - Use shared_examples to avoid duplicate test examples

It's common to see a before_action method that need executing in different controller actions. At the same time, when writing RSpec tests for these actions, it's easily to write down context blocks whose test examples are almost the same, and only a let declaration is different. The code might

What's the difference between find_each, find_in_batches, in_batches in Rails?

What's the difference between find_each, find_in_batches, in_batches in Rails?

Sometimes we will use klass_name.all to get records from the database. That’ll be ok, if we only have 100 records in the database. However, using klass_name.all might not be the best way to get records, especially when we need to query large numbers of records.

Before adding a new validation, one thing you should notice

Before adding a new validation, one thing you should notice

When we develop a new feature, it's common to add a new column that needs some validations in the model. So, we might write something like this: class Book < ApplicationRecord #... validates :barcode, presence: true end To increase the test coverage, adding the test example is necessary: RSpec.describe Book, type:

Git - There are too many unreachable loose objects

Git - There are too many unreachable loose objects

To Reproduce: * git cm 'some_message' * commit successfully, but git showed the message below: error: The last gc run reported the following. Please correct the root cause and remove gc.log. Automatic cleanup will not be performed until the file is removed. warning: There are too many unreachable loose objects;