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% Document Info
\author{dwapi}
\pdfinfo{
  /Title (migrations-and-misc-rails-reference.pdf)
  /Creator (Cheatography)
  /Author (dwapi)
  /Subject (Migrations and Misc Rails Reference Cheat Sheet)
}

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\noindent
\begin{multicols}{3}
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    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Migrations and Misc Rails Reference Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{dwapi} via \textcolor{DarkBackground}{\uline{cheatography.com/43665/cs/13036/}}}
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\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}dwapi \\
  \uline{cheatography.com/dwapi} \\
  \end{tabulary}
\vfill
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 8th October, 2017.\\
   Page {\thepage} of \pageref{LastPage}.
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\vfill
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
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  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
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\end{multicols}}




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\begin{multicols*}{2}

\begin{tabularx}{8.4cm}{X}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{ORM (Object Relational Mapping)}}  \tn
% Row 0
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Advantages}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{\{\{fa-plus-circle\}\} DB independent. moving from PG to Sqlite should be trivial.\{\{nl\}\}\{\{fa-plus-circle\}\} Cleaner code focused on business logic rather than SQL Query\{\{nl\}\}\{\{fa-plus-circle\}\} Relationship/Association Management\{\{nl\}\}\{\{fa-plus-circle\}\} Model Objects can be cached -{}- No need to repeatedly query DB for same data\{\{nl\}\}\{\{fa-plus-circle\}\} Transaction support\{\{nl\}\}\{\{fa-plus-circle\}\} Built in validation before save} \tn 
% Row Count 10 (+ 9)
% Row 2
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Disadvantages}}} \tn 
% Row Count 11 (+ 1)
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\mymulticolumn{1}{x{8.4cm}}{\{\{fa-plus-circle\}\} Abstraction = overhead (uses more memory etc...)\{\{nl\}\}\{\{fa-plus-circle\}\} SQL ignorance} \tn 
% Row Count 14 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Create Table (with Datatypes)}}  \tn
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\mymulticolumn{1}{x{8.4cm}}{\# CREATE \newline  \newline class CreateOrders \textless{} ActiveRecord::Migration{[}5.1{]} \newline   def change \newline     create\_table :orders do |t| \newline        \newline        t.belongs\_to :category \newline  \newline        t.binary :photo \# PG: bytea   MySQL: blob \newline        t.boolean :success \# PG: boolean   MySQL: tinyint(1) \newline        t.date :ship\_date \# PG \& MySQL: date   \newline        t.datetime :order\_date \# PG: timestamp   MySQL: datetime \newline        \# PG \& MySQL: decimal  Precise.  Use for currency, geolocation \newline        t.decimal :latitude, :decimal, :precision =\textgreater{} 15, :scale =\textgreater{} 13  \newline        t.float  \# PG \& MySQL: float  Less precise thank decimal \newline        t.integer :age \# PG: integer   MySQL: int(11) \newline        t.string :name \# PG \& MySQL: varchar(255)   \newline        t.text :comments \# PG \& MySQL: text   \newline        t.time :ship\_time \# PG \& MySQL: time   \newline        t.timestamps  \# PG: timestamp   MySQL: datetime \newline  \newline     end \newline   end \newline end} \tn 
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\begin{tabularx}{8.4cm}{X}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Generators}}  \tn
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\mymulticolumn{1}{x{8.4cm}}{rails g model comment    post:references     text:string} \tn 
% Row Count 2 (+ 2)
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\mymulticolumn{1}{x{8.4cm}}{rails g migration add\_post\_to\_user       post:belongs\_to} \tn 
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\mymulticolumn{1}{x{8.4cm}}{rails g migration AddUserRefToProducts      user:references} \tn 
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\mymulticolumn{1}{x{8.4cm}}{rails g migration AddPartNumberToProducts      part\_number:string} \tn 
% Row Count 8 (+ 2)
% Row 4
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\mymulticolumn{1}{x{8.4cm}}{rails generate controller Sessions new} \tn 
% Row Count 9 (+ 1)
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\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{rails db: command}}  \tn
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Rollback the last migration:}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}rails db:rollback} \tn 
% Row Count 2 (+ 2)
% Row 1
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Revert the last 3 migrations:}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}rails db:rollback STEP=3} \tn 
% Row Count 4 (+ 2)
% Row 2
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Rollback and then migrating back up:}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}rails db:migrate:redo STEP=3} \tn 
% Row Count 6 (+ 2)
% Row 3
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Run specific migration}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}rails db:migrate:up VERSION=20080906120000} \tn 
% Row Count 8 (+ 2)
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Load test fixtures}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}rails db:fixtures:load} \tn 
% Row Count 10 (+ 2)
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Create a db/schema.rb file that can be portably used against any database supported by ActiveRecord}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}db:schema:dump} \tn 
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Load a schema.rb file into the database}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}db:schema:load} \tn 
% Row Count 16 (+ 2)
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Dump database structure to SQL file Drops the database, creates the datab}}} \tn 
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% Row Count 19 (+ 3)
% Row 8
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Clone your database structure into the test database}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}db:test:prepare} \tn 
% Row Count 22 (+ 3)
% Row 9
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Drops the database, creates the database and then runs migra- tions against the database. Takes a VERSION argument as well as RAILS\_ENV}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}db:reset} \tn 
% Row Count 26 (+ 4)
% Row 10
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Create/clear Sessions table}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}db:sessions:create (or :clear)} \tn 
% Row Count 28 (+ 2)
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Postgres Specific Data Types}}  \tn
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\mymulticolumn{1}{x{8.4cm}}{:hstore	\# Key =\textgreater{} Val Hash Store \newline :json	        \#The json data type stores an exact copy of the input text \newline :jsonb	\# stored in a decomposed binary format \newline :array	 \newline :cidr\_address	\#IP Address \newline :ip\_address	\#IP Address \newline :mac\_address	\#String} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\mymulticolumn{1}{x{8.4cm}}{In other DBs these are all stored as strings}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Change Table}}  \tn
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\mymulticolumn{1}{x{8.4cm}}{class AddPartNumberToProducts \textless{} ActiveRecord::Migration{[}5.0{]} \newline   def change \newline      \newline     add\_index :products, :part\_number \newline     remove\_index :products, :part\_number \newline  \newline     add\_reference :this\_table, :other\_table, index: true \newline     remove\_reference :this\_table, :other\_table, index: true \newline      \newline     belongs\_to:  \newline     add\_column :products, :part\_number, :string \newline     add\_column :products, :column\_name, :string, :limit =\textgreater{} 50     \newline  \newline     rename\_column :shoes, :season, :season\_id \newline     t.change :column\_name, :new\_column\_type \newline     change\_column\_default :table\_name, :status, 0 \newline     t.remove :column\_name \newline      \newline  \newline   end \newline end} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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% That's all folks
\end{multicols*}

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