My Ruby on Rails project cheatsheet: Stuff I’ve had to look up 100 times

Hello, World.

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Form_for template

<%= form_for @user do |f| %> 
<%= f.label :name %>  
<%= f.text_field :name %><br />  
<%= f.label :age %>  
<%= f.number_field :age %><br />  
<%= f.label :password %>  
<%= f.password_field :password %><br />  
<%= f.submit %>
<% end %>

Flash message

In controller: 
flash[:alert] = "User not found."
OR
flash[:notice] = "Successfully logged in."
In view: 
<% if flash[:notice] %>
<div class="notice"><%= flash[:notice] %></div>
<% end %>

Link_to

<%= link_to "text", "/add-link--here" %>
OR replace with URL helpers in both spaces

Naming convention for many-to-many join tables

Migration table naming convention: groups_users
Migration file naming convention (the part of the file name that is not automatically generated): create_groups_users
Model class naming convention: GroupsUser
Model file naming convention: groups_user.rb

Render partial

In view:
<%= render 'author' %>
Partial with local variables: 
<%= render partial: "authors/author", locals: {post_author: @post.author} %>
<%= @post.title %>
<%= @post.content %>

Routing

Shortcut to create all CRUD routes for one resource:

resources :users

Syntax to limit routes with resources:

resources :users, only: [:new, :create]

Validations

validates :name, :presence => true