Categories
Programming

Getting Stuck on the Version of Rails In Your Bundler

Confusingly, bundler can have more than one version of Rails installed at once. if you had many versions, when you ran rails new, it probably used the default one, which could have been a very old one for you. This often confuses new developers, and especially if you installed Rails years ago and then come back to pick it up again.

To see which versions of Rails you have installed in bundler, use

gem list |grep rails

(here you are grepping, or searching against, the output for the string “rails”; without grep you would see all of your gems)

You’ll see some other gems with the name “rails” in them too, fortunately, all the rails gems are numbered concurrently.

TO install a different version of Rails in your bundler (remember, this just installs the gem code in your bundler’s system ready for use)

gem install rails -v 5.2.4.3

Finally, if you want to force rails new to use a specific version, use underscores before the “new” (that is, between “rails” and “new”)

rails _6.0.3.2_ new

Categories
Programming

Common Core JS Quick Setup

I am pleased to announce a rapid application development tool for Rails: It’s called “Common Core JS.”

The source code is on Github. When you install it, the gem is pulled from RubyGems.

The finished result of the example app we will build today can be seen here. (I recommend you type out each step and only refer to this if you need to.)

It’s based on the idea that you will embrace a common naming convention for your Rails app, will use AJAX rendered-everything (that means all the forms are remote: true), and want a common set of tools for rolling out a quick, dashboard-like app in Rails.

It comes with poor-man’s authentication built-in. Poor man’s auth is safe and works fine, but it isn’t designed for you to grow your entire app on and you should graduate out of if you have any granularity to your access control.

Common Core is a fantastic tool for rapidly building prototypes. It can also be used to create API back-ends for Javascript-heavy apps.

It is a blunt instrument and you should wield it carefully. In particular, you’ll want to remove specific code that it creates because it can create situations where users may have the access they shouldn’t.

Quick Setup

Let’s build the fastest app you can possibly build in Rails.

I’ll call it MyGreatApp, but yours can be named anything of coruse.

rails new MyGreatApp

Once you have the app generated (and even on faster processors Rails new still takes a hot minute or two), go to modify the Gemfile

Add the Gem

gem 'common_core_js'

To your Gemfile.

Then run: bundle install

Setup The Common Core

Then run the Common core install generator (which is implemented as a generator, not a rake task)

bundle exec rails generate common_core:install

Now you’ll create a User objeect, with a migration and model.

do this using. Note that you should not add any fields that will conflict with Devise fields, like email (I’ll add those in the next step).

bundle exec rails generate model User name:string joined_date:date timezone:integer

Add Devise

Add devise to your Gemfile

gem 'devise'

run bundle install, then install devise on the User model:

rails generate devise:install
rails generate devise User

Take a look at the fields on your User database table now. (Here I’m using DB Browser for SQLite)

Notice the fields added name, joined_date, and timezone I’ve put a red box around and the devise fields, including email and encrypted_password, I’ve put a blue box around.

Now you have the most bare-bones Rails app with Devise gem installed. This is great because you get free sign up, login and forgot password fundionality immediately.

Go to

http://127.0.0.1:3000/users/sign_up

Add jQuery

Add jQuery to your package.json via yarn

yarn add jquery

Go to config/webpack/environment.js and add this code in between the existing two lines

const webpack = require('webpack')
environment.plugins.prepend('Provide',
  new webpack.ProvidePlugin({
    $: 'jquery/src/jquery',
    jQuery: 'jquery/src/jquery'
  })
)

The complete environment.js file looks like so (the part you are adding is shown in red.)

const { environment } = require('@rails/webpacker')

const webpack = require('webpack')
environment.plugins.prepend('Provide',
  new webpack.ProvidePlugin({
    $: 'jquery/src/jquery',
    jQuery: 'jquery/src/jquery'
  })
)

module.exports = environment

Add require("jquery") to your app/javascript/packs/application.js file so it looks like so.

While we are here, let’s also add the common_core javascript too using require("common_core")

The change code is shown in red.

require("@rails/ujs").start()
require("turbolinks").start()
require("@rails/activestorage").start()
require("channels")
require("jquery")
require("common_core")

Adding Bootstrap

Next let’s add Boostrap to the Gemfile

gem 'bootstrap', '~> 4'
gem 'font-awesome-rails'

Next delete app/assets/stylesheets/application.css

And replace it completely with a new file

app/assets/stylesheets/application.scss

(Do not save the old application.css file or rename and append to it; do not include the contents from the old file in the new .scss file)

@import 'bootstrap';
@import 'font-awesome';
@import 'common_core';

Test it

Now go ahead and start your rails server with bundle exec rails server

Go to /users/sign_up and create a new user account (be sure to enter the same password twice)

You will then be redirected to the Home page, which is now the Ruby on Rails “Yay you’re on Rails.” That’s fine— go ahead and customize your root URL.

Today’s Example App

I’ll make a super-simple system today where Users have many Events An Event belongs to a Format, which in our fictional world is only two choices: Zoom or Outdoor.

Events have a name, a starting datetime, and an ending datetime, and a “publicize” date on which should be before the starting time.

The two datetime fields (starting_at and ending_at) and the date field (publicize_on) can be empty (nil), but if set they are enforced to be: starting_at must be before ending_at. publicize_on must be before starting_at.

An Event will belong_to a Format (class & table). Formats will have a name field and only two records: Zoom and Outdoor. (We can assume they will be id 1 and id 2 in the formats table.)

All Events must belong_to a format, and when we create or edit an Event we can switch its format, but the format cannot be blank (null).

We already have the User object, and we also already have all the login, logout forgot password, and more provided by Devise.

We want the users to log-in and go to a dashboard of their own events.

They should be able to create, edit, & delete their own events with only the validations discussed above.

They should not be able to edit or create events belonging to other users, even by hacking the query parameters.

Finally, the user should be able to edit their own name and timezone, but not any other user’s name or timezone.

Because we want to name our routes from the perspective of the context-interaction, we’ll namespace the controller to Dashboard:: in our Ruby code and /dashboard in the URL. The controller will be at controllers/dashboard and the views will be at views/dashboard

Make the models

Since you already made the User model in the devise setup, let’s go ahead and create the Events and Formats tables.

run

bundle exec rails generate model Event user_id:integer name:string start_at:datetime end_at:datetime promote_on:date description:string format_id:integer

Then open up the migration file and ed the description line, adding a larger than 256 limit, like 400

Next run bundle exec rake db:migrate to create the table.

Before I go further, let’s edit our models just a bit.

Open models/user.rb and add has_many :events

also add validates_presence_of :name

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable

  has_many :events
  validates_presence_of :name
end

Likewise, on the Event object, defined models/event.rb, you’ll need to add the reflexive relationship for belongs_to :user and belongs_to :format

class Event < ApplicationRecord
  belongs_to :user
  belongs_to :format
end

Now make a formats table

bundle exec rails generate model Format name:string

      invoke  active_record
      create    db/migrate/20200808233939_create_formats.rb
      create    app/models/format.rb
      invoke    test_unit
      create      test/models/format_test.rb
      create      test/fixtures/formats.yml

Modify the migration file to create to dummy Formats, adding this to after end of the create_table block

Because the COVID quarantine prohibits indoor events during 2020, we want to make only two format records: “Zoom” and “Outdoor” events.

Format.create(name: "Outdoor")
Format.create(name: "Zoom")

Your edited migration looks like

class CreateFormats < ActiveRecord::Migration[6.0]
  def change
    create_table :formats do |t|
      t.string :name
      t.timestamps
    end

    Format.create(name: "Outdoor")
    Format.create(name: "Zoom")
  end
end

Then run the migration itself, which will now make the table & the two format records.

bundle exec rails db:migrate

====================================
-- create_table(:formats)
   -> 0.0025s
== 20200808233939 CreateFormats: migrated (0.0027s) ===========================

Now we have two Formats in our database.

Localized Timezone Support

In order to show dates, we use a localized date display: the date & time is always shown to the user in their own date. To do this you have a few choices: (1) You can save the timezone to the user’s table, and let them set it for themselves, (2) You can show everybody the server’s date

Option #1 – Store timezone On the User object

We already took care of this by adding timezone to our User object.

Option #2 – Use the Server’s Timezone

If the auth object (current_user) does not respond to timezone, the Rails “system clock” will be used. The system clock’s timezone as set by the Rails app is used. This is often the timezone of the headquarter’s of the company that owns the application. (That is, if you do not know the user’s context, you simply use your own company’s context instead.)

Make the Controller, Views & Specs

Next we’re going to do the thing. We’ll make two controllers: Dashboard::EventsController for editing events and Dashboard::UsersController for the user editing their own name.

First, let’s create the Events Controller

rails generate common_core:scaffold Event namespace=dashboard --with-index

A few things to note

  1. Use the ‘generate’ command, not a rake task.
  2. When passing the model name, pass it in the singular form
  3. Here I’ve provided the namespace= with a value of dashboard. You will this is important to how our code comes out.

Here is the heart & soul of the common core: 5 .js.erb files, 5 .haml files, a controller, and a controller spec. Also along for the ride came controllers/dashboard/base_controller.rb as well as views/dashboard/_errors.haml, and layouts/_flash_notices.haml

Take a peak through all the generated code now.

Pay particular attention to _line.haml and _form.haml. You will note _form.haml conveniently is used for both the new/create actions and also for the update action, unifying the layout of your record across CRUD.

You can use both to customize your app quickly and easily.

One more quick step, add this to your routes.rb file.

Make sure to nest the :events route within the :dashboard namespace, as shown here. If you aren’t familiar with namespacing in Rails, check out this blog post on my other blog, The Rails Coach.

Rails.application.routes.draw do
  devise_for :users

  namespace :dashboard do
    resources :events
  end
end

Start your server with

bundle exec rails server

If the Common Core finds null for timezone on your User object, it will default to either (1) whatever is set for your Rails app in either application.rb or an environment file, or, if don’t have this set (2) the clock timezone of the server that is running your Ruby application.

It’s generally a good idea to set your Rails app timezone to the same timezone of your company’s headquarters, and then don’t change it, because that way if your server happens to move from one timezone to another (for example, you migrate from a server on the East coast to the West coast), your app will be unaffected. If your company changes timezones, you can either leave the Rails app as-is or change it, but be sure to note any place where your default timezone comes through.

config.time_zone = 'Eastern Time (US & Canada)'

Done!

We can now do all of these fancy thigns.

Create an event. Leave name or format blank, get an error.

When you create a new event, you must give it a name and Format. Notice how if you don’t, the Rails-side logic will return the form shown with the erroneous fields marked in red.

Edit an Event

Your model-level validations — name and format as required — are enforced in the update action as well.

Deleting An Event

Adding Validation

Add this to your Event class in app/models/event.rb

validate :start_at_before_end_at, if: -> {!start_at.nil? && !end_at.nil?}

def start_at_before_end_at
  if end_at < start_at
    errors.add(:start_at, "can't be after end at")
    errors.add(:end_at, "can't be before start at")
  end
end

*Validation magic*

Finally, to add validation on all the date fields, here’s our completed Event model

class Event < ApplicationRecord

  belongs_to :user
  belongs_to :format


  validates_presence_of :name

  validate :start_at_before_end_at, if: -> {!start_at.nil? && !end_at.nil?}
  validate :promote_on_before_start_at, if: -> {!promote_on.nil? && !start_at.nil?}

  def start_at_before_end_at
    if end_at < start_at
      errors.add(:start_at, "can't be after end at")
      errors.add(:end_at, "can't be before start at")
    end
  end

  def promote_on_before_start_at
    if start_at < promote_on
      errors.add(:promote_on, "can't be after start at")
    end
  end
end

Account Dashboard

Next we’re going to create the very simplest of Account Dashboards. Remember that Devise already handles log in, log out, and forgot password, meaning most of the heavy lifting of user authentication has been taken care of.

In this simple app, we want an Account dashboard that let’s us edit only two fields: name and timezone.

First let’s add the route to routes.rb

Rails.application.routes.draw do
  devise_for :users
  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html

  namespace :dashboard do
    resources :events
    resources :users
  end
end

Next let’s generate some scaffold

rails generate common_core:scaffold User namespace=dashboard

We now instantaly have a very basic dashboard for the User to edit their own details

The final finishing touch here will be to make the Timezone into a drop-down.

To do this, we’ll create a non-AR model :

class UsTimezone
@@_US_TIMEZONES = {
-5 => 'Eastern',
-6 => 'Central',
-7 => 'Mountain',
-8 => 'Pacific',
-10 =>'Hawaii–Aleutian'
}
def self.all
@@_US_TIMEZONES.collect{|k,v| OpenStruct.new({label: v, value: k})}
end


def self.utc_to_name(input) # in hours
utc = input[0...-2].to_i
return @@_US_TIMEZONES[utc]
end
end

Next go into the views/dashboard/users/_form.haml and we’re going to make our first cutomization

We’re going to add this:

= f.collection_select(:timezone, UsTimezone.all, :value, :label,  {:prompt => true, value: @user.try(:timezone) }, class: 'form-control')

The full file looks like this

.row
  %div{class: "form-group col-md-4 #{'alert-danger' if user.errors.details.keys.include?(:name)}"}
    = f.text_field :name, value: @user.name, size: 256, class: 'form-control', type: ''
    %label.form-text
      Name

.row
  %div{class: "form-group col-md-4 #{'alert-danger' if user.errors.details.keys.include?(:joined_date)}"}
    = date_field_localized(f, :joined_date, @user.joined_date, 'Joined date', current_user.timezone)
.row
  %div{class: "form-group col-md-4 #{'alert-danger' if user.errors.details.keys.include?(:timezone)}"}
    = f.text_field :timezone, value: @user.timezone, size: 256, class: 'form-control', type: ''
    %label.form-text
      Timezone
.row
  %div{class: "form-group col-md-4 #{'alert-danger' if user.errors.details.keys.include?(:email)}"}
    = f.text_field :email, value: @user.email, size: 256, class: 'form-control', type: ''
    %label.form-text
      Email

First, take away the strikethrough text above. This is the text field for the timezone that we don’t want.

In its place, add the new collection_select

.row
  %div{class: "form-group col-md-4 #{'alert-danger' if user.errors.details.keys.include?(:timezone)}"}
    = f.collection_select(:timezone, UsTimezone.all, :value, :label,  {:prompt => true, value: @user.try(:timezone) }, class: 'form-control')
    %label.form-text
      Timezone

We now have a nice drop-down for our Timezone field. You can replicate this pattern for any field that you want to turn into a drop-down.

Conclusion

Common Core JS harnesses the power of many great things about Rails:

• Database migrations

• ActiveRecord assocations (has_many, belongs_to, etc)

• Scope chains for access control

• Devise for athentication

Remember, make your models first: Add limits and defaults to your database fields by modifying your migrations. Then add the relasionships between the tables using standard ActiveRercord has_many, belongs_to, and has_one.

Then build the common core scaffolding & customize the views and controllers it produces.

With these powerful tools, you can build a dashboard-like app in minutes, complete with simple interface buttons that let your users accomplish most of what they’ll need. The philosophy is that you will want this dashboard as you initially introduce people to your product. The main logic of your application will likely live more in the models, service objects, and domain layer (business logic) parts of your Rails app. For this reason, you are encouraged to customize the files only lightly. (Add some verbiage or change the CSS to customize the look & feel.)

The code you build with common core is cheap and disposable. It is not very modern, but it gets the job done. It is just “good enough” to launch a sophisticated app on, but it isn’t good enough to impress your users with a really good UI.

For that, you’ll want to throw away the front-end code and replace it with a modern JS UI like React, Vue, Ember, or Angular.

By that time, the Common core will have already helped you build (1) a prototype, (2) your business logic, and (3) possibly even some controllers you can re-use (for example, remove the format.js responses and replace them with format.json to change the controllers into a JSON-responding API controller.)

Enjoy your rapid prototyping!

Categories
Programming

How to Get Emojis in MySQL (fixing Incorrect String Value)

So your Rails application with a MySQL database was humming along and all of a sudden it hit this error:

Mysql2::Error: Incorrect string value: '\xC5\x99\xC3\xA1k

What does that mean? Upon inspection you realize that someone has typed into your website the all-too-favorite Millenial communication tool: the emoji. ?✨

MySQL needs a little massaging. For steps 1 & 2 in Rails, create a new database migration and use execute to run these commands directly onto your database.

  1. Make sure you actually alter the database’s character set

ALTER DATABASE <DATABASE NAME> CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;

Where <DATABASE NAME> is your database. in Rails, because we have different database names for different environments, try this inside of your migration…

execute "ALTER DATABASE #{ActiveRecord::Base.connection.current_database} CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;"

  1. Make sure you ALTER the TABLE AND FIELD where you want to insert the character set

ALTER TABLE CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE modify TEXT charset utf8mb4;

(If you made a Rails migration, you can do this in the same migration using another execute.)

IMPORTANT: I have assumed above that your field is of type TEXT. If it is not, change your field’s type definition before running this. If you don’t, you’ll convert your existing field to a TEXT field even if you didn’t want to.

  1. Restart your MySQL instance (DO NOT FORGET)
  2. In Rails, you must also specify the encoding & collation in the MySQL adapter which you will find in your config/database.yml file (where you have specified mysql2 as the adapter).

For example:

production:
encoding: utf8mb4
collation: utf8mb4_general_ci

or if you want it in your default configs

default: &default
encoding: utf8mb4
collation: utf8mb4_general_ci

See also…

https://stackoverflow.com/questions/22464011/mysql2error-incorrect-string-value#22464749

https://stackoverflow.com/questions/16350310/mysql-mysql2error-incorrect-string-value/18498210#18498210

https://stackoverflow.com/questions/16350310/mysql-mysql2error-incorrect-string-value/16934647#16934647

Categories
Programming

Halfway to One Point Oh: UTM Version 0.5

Today I’ve finished version 0.5 of my new Gem, Universal Track Manager.

It’s a plug-and-play Rails engine that you install into your Ruby on Rails application with just three simple steps (see the README). You can then immediately pick up your visitors’:

IP address
Ad campaign where they came from
the browser they are using

In my next version, I’ll add support for http referrer and more too. Give it a try today.

If you like the Gem, please ‘star’ it on Github or download it from RubyGems (you do that just by running bundle install). Also, consider supporting it today with a small contribution today through the Github sponsors program. Sponsors levels start at just $1/month.

Categories
Programming

Universal Track Manager Version 0.4

Today I’m announcing Version 0.4 of my new Gem: Universal Track Manager.

It’s an great little utility project that will surely have appeal to many websites and developers.

Visitors come to your site every day. Along with their visits, four key pieces of information come along for the ride:

— IP address
— browser name (which lets you infer operating system and sometimes device)
— UTM parameters (if they clicked from another site or an ad campaign)
— HTTP referrer, (which shows if they clicked directly from another site to your site, even when no UTMs are set)

Universal Track Manager, a play-on-words that shares an acronym with “UTM Parameters,” is a plug & play gem to automatically scoop up this information and stash it into your database. You can think of it like a built-in Google Analytics (without the fancy dashboard).

With a tiny bit of trickery, support for Viewport size too is possible (width X height of the users’s window), which can let you determine if the user is on a desktop or mobile browser.

Today I’ve bumped the version up to 0.4. (I realize I made a 10x version change but this Gem is nearing its ‘version 1.0’ release so I am anticipating that when it is feature complete.)

This is the second version I’m dubbing as ‘public beta.’ Although this is production-quality code, it should be used with caution until it is no longer in BETA status. Please give it a try on your Rails projects today. With an easy 3-step installation into any Rails 4+ app and you can sit back and sweep up tracking info on your visitors.

*MOST* of the core functionality now works! This version 0.4 implements fully support for timestamping your visits, the user’s IP address, browser, and UTMs.

Support for HTTP referrer and more coming soon! Kindly submit feedback via Github.

Links:

Github Repo

Rubygems page

Categories
Programming

Announcing Nonschema Migrations — NOW FOR RAILS 6!

Nonschema migrations version 5.0.0: RubyGems Page, GitHub page

Now compatible with Rails 6, nonschema_migrations is the best way to separate your schema changes from your data changes.

Want to run no-downtime deploys with data-only migrations? No problem.

Install it in your Rails app today to see what a difference data migrations can make.

Shout out to Mikls Fazekas who hails all the way from Gyenesdis, Hungary for the pull request for this release!

Categories
Programming

Jason FB’s 10 Magical Ruby Developer Tools

1. deivid-rodriguez/byebug
Byebug is a fantastic debugger available for Ruby 2 (and presumably above). Drop

gem ‘byebug’

into your Rails app Gemfile and bundle install. In either your test run or your development run, write

byebug

on a single line of your app and voila. When you hit that line, you will drop into the debugger.

If you’re not developing a Rails app, you can include ‘byebug’ at the top of your Ruby file.

Full docs here.

2. pretty print (pp)

Pretty print is one of my favorite introspection weapons to help see variables more clearly.

pretty print, which you write as pp, prints out your object with each attribute on its own line. Take for example this Spree::Country object, shown here on the Rails console without pretty print

2.4.6 :010 > x
=> #<Spree::Country id: 232, iso_name: “UNITED STATES”, iso: “US”, iso3: “USA”, name: “United States”, numcode: 840, states_required: true, updated_at: “2019-05-19 17:16:07”, zipcode_required: true>

Now, with pretty print, the same object is conveniently displayed with each attribute as its own line. This is invaluably helpful when you have deep nesting of objects.

2.4.6 :009 > pp x
#<Spree::Country:0x00007fd8507ea358
id: 232,
iso_name: “UNITED STATES”,
iso: “US”,
iso3: “USA”,
name: “United States”,
numcode: 840,
states_required: true,
updated_at: Sun, 19 May 2019 17:16:07 UTC +00:00,
zipcode_required: true>

3. puts, .to_s, and inspect

OK, so we get a 3-in-1 here: When you call puts on an object, .to_s will be called and then output to your screen. So you should make your objects have a .to_s that is human readable, possibly even for use in, say, a drop-down menu or label. 

def class Person
 attr_accessor :first_name, :last_name

 def to_s
   “#{first_name} #{last_name}”
 end
end

inspect, on the other hand, is specifically for developers. In this method, you would write out as much information as you the developer (or next developer) want to see, including the keys (ids) of your objects if those will be helpful:

def class Person
 attr_accessor :first_name, :last_name

 def inspect
   “Person id: #{id} – first: #{first_name}; last: #{last_name}”
 end
end

Your objects should have both .to_s and .inspect on them, and you can try these universally named Ruby methods on other people’s objects to examine them. A well-formed codebase implements them or has helpful output for both of these.

4. .to_yaml
Pretty print’s cousin is the .to_yaml method, which will take your object and convert it into yaml. Take for example this arbitrary object, which you will notice contains a :ghi key that has a nested object as its value:

2.4.6 :023 > x= {abc: 1, def: 4, ghi: {ye: 6, nm: 3}}
=> {:abc=>1, :def=>4, :ghi=>{:ye=>6, :nm=>3}}
2.4.6 :024 > x
=> {:abc=>1, :def=>4, :ghi=>{:ye=>6, :nm=>3}}

.to_yaml on its own will produce a string that will output with newline characters, like so:

2.4.6 :025 > x.to_yaml
=> “-\n:abc: 1\n:def: 4\n:ghi:\n :ye: 6\n :nm: 3\n”

To make this more useful, try puts along with .to_yaml

2.4.6 :026 > puts x.to_yaml

:abc: 1
:def: 4
:ghi:
 :ye: 6
 :nm: 3

5. x.method(:_____).source_location

(where :_____ is name of the method — as a symbol — you are trying to search for)

OK, so the ultimate secret weapon of Ruby debugging is this little-known method that will magically — and I mean magically — tell you where a method was defined. That’s right, I mean the actual line number itself.

2.2.5 :002 > a.method(:hello)
=> #<Method: Apple(Thingy)#hello>
2.2.5 :003 > a.method(:hello).source_location
=> [“/Users/jason/Projects/nokogiri-playground/app/models/thingy.rb”, 2]

Look, ma, take a peek into my hard drive and you would find that the hello method is actually defined on the file at the full path /Users/jason/Projects/nokogiri-playground/app/models/thingy.rb on line 2.

Like magic it works for Rails and Gem code too, and is invaluable when you are ready to dive into the APIs you are working with.

6. x.methods
By default this method will return a list of all of the methods on an object. Watch out because you’ll get all the methods on the ancestor chain too.

In older versions of Ruby, you could use this method to examine the instance methods that were defined on this class only (excluding the ancestors), but unfortunately this no longer works.

If you pass this method false, like so:

x.methods(false)

…things get more interesting: then you get only the class methods defined on this object’s class itself. (Remember in Ruby class methods are defined with self.)

7. brunofacca/active-record-query-trace

An excellent gem that’s still a non-optional workhorse in my development practice – especially when debugging a legacy codebase. This gem will display for ALL of your SQL queries where in your Ruby or Gem code the active record update commands are coming from.

Follow the instructions in the Gem to create an initialize file and set it up. My only tip here that adds to the docs is that you’ll want to set the number of lines:

ActiveRecordQueryTrace.lines = 10

I find that when debugging a problem in my own Rails app I want this set to a lower number (like 5 or 10) and when debugging a problem in Gem code or in Rails I need this at a much higher number (like 50 or 100).

8. flyerhzm/bullet

Understanding N+1 queries is a significant litmus test that sets amateurs from the professionals. Bullet is like a magic bullet – literally named so – for finding your N+1 queries.

Bullet is a great gem that you should install in either development or test, not in production. Often because it does add overhead to your speed, I install it but leave it configured so that it is turned off by default and any developer on the team who needs it can turn it on.

You CAN and SHOULD turn it on periodically too, to examine where your app is producing N+1 queries.

Here’s the catch with Bullet: Remember that Active Relation objects are created as chains of conditions before they get translated and executed as SQL. That’s why when you do this you must carefully consider

query = Country.where(name: “United States”)

When you do this in your Rails console, you will see it run the SQL right away.

2.4.6 :039 > Spree::Country.where(name: “United States”)
 Spree::Country Load (0.7ms) SELECT `spree_countries`.* FROM `spree_countries` WHERE `spree_countries`.`name` = ‘United States’ LIMIT 11

It only does this because of the ‘print’ effect the Rails console has on your objects. If you string another .where onto this object, when translated into SQL, ActiveRecord will combine the queries:

query = Spree::Country.where(name: “United States”); query.where(iso: “US”);
 Spree::Country Load (1.0ms) SELECT `spree_countries`.* FROM `spree_countries` WHERE `spree_countries`.`name` = ‘United States’ AND `spree_countries`.`iso` = ‘US’ LIMIT 11

The reason this is important is that to understand where your N+1 queries are coming from you need to understand when you are creating your Active Relation objects and when they are invoked. They are not the same place, although on the Rails console it makes you think it is one and the same. When you grok this, you will see why Active Record’s side loading (which loads a related set of objects in a single optimized query, taking the number of queries from N+1 to 1+1=2) is both efficient and can be tricky to work with, especially with objects that have many relationships.

Don’t be fooled: Side-loading is nearly always more efficient than N+1 queries. 

Bullet tells you where those pesky N+1 queries are invoked, but not where you are creating them. What you then need to do is trace your code (manually) to figure out where the queries are being created, which hopefully should be near in the code to where they are being invoked ( but in the case of complex filtering logic might not be).

Here you need to add the appropriate .joins(:____) to your code anywhere between when the objects are set up and when they are invoked by Active Record. Note that you’ll only want to join in those additional tables if they are actually used. If not, you don’t need the over head.

You’ll know you’ve solved your N+1 queries because you won’t see them output in your Rails log, and they’ll disappear from the Bullet code.

9. better_errors

Since Rails 4 adopted a near identical default, this used to be more interesting. For a Rails 3 app it can bring your error crash console up to Rails 4 standards.

10. Introspect, Introspect, Introspect but remember Ruby’s last-line quirk

Always look at what you’re doing. Drop into your debugger, look at your variables, clone & freeze them, look for race conditions, look for flip-floppers, watch out for your own confirmation bias. Remember that when in the debugger or on the Rails console and you type a SINGLE VARIABLE and HIT RETURN, the console will interpret that action as-if you had called .inspect

2.2.5 :007 > a
=> #<Apple id: nil, created_at: nil, updated_at: nil>
2.2.5 :008 > a.inspect
=> “#<Apple id: nil, created_at: nil, updated_at: nil>”

In some cases, the act of inspection actually changes the object (like in the case of an Active Relation, in which case it invokes the query), so keep that in mind (we might call this the “observer effect” in software development.)

Categories
Programming

Amazon RDS on Heroku Still Works

Although Heroku has put a lot of attention into their own Postgres-based datbase architecture, Heroku Data, this article still works for rebels who want to use Amazon RDS on Heroku:

https://devcenter.heroku.com/articles/amazon-rds

Note that I can’t seem to get “sslca” to work as a config option in my database.yml file (in Rails), I get this I get an error after deploying, upon connection

SSL_CTX_set_default_verify_paths failed

This happens when configuring by database.yml, which I shouldn’t be doing anyway.

Nonetheless, the configuration by DATABASE_URL (which is preferred for security anyway), does actually work.

Although it continues to work in 2018, this may not be good long-term strategy as my last conversations with Heroku support led me to conclude that their failover policies for catastrophic failures aren’t set up for an RDS- backed solution unless you go into Heroku Private Spaces, which you need to be an enterprise client for.

Categories
Programming

How to Install an Older Version of Rails

My post from four years ago with this same title is Google’s #2 result for a search for “How to Install an Older Version of Rails,” so I thought I’d make a repost with some updates.

You can install an older version of rails using this syntax:

rails _5.1.6_ new my-test-app

(Where “5.1.6” is the version you want and “my-test-app” is the name of your new rails app.)

Yes, you actually type those underscores around the version number.

If you get …

can’t find gem railties (>= 0.a) (Gem::GemNotFoundException)

You probably don’t have the right version of Rails itself installed as a gem; try this:

rails install -v=5.1.6

or…

gem install rails -v 5.1.6

Then try again with…

rails _5.1.6_ new my-test-app
Categories
Programming

Announcing Nondestructive Migrations Version 1.3 for Rails 5.1

I am pleased to announce Version 1.3 of my gem nondestructive_migrations. With this update, nondestructive_migrations is ready for Rails 5.1.

The Gem’s Github page can be found here:

https://github.com/jasonfb/nondestructive_migrations and you’ll find a sample app for Rails 5.1 here.

Version 1.3 is officially pushed to Rubygems as of this morning.

I know I’m slightly behind the Rails release schedule itself. (We just had Rails 5.2 officially released last month.) Thanks to some help from Mikls Fazekas from Hungary hopefully this gem should be ready for Rails 5.2 soon. Watch this space for updates!