1 | == Welcome to Rails |
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2 | |
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3 | Rails is a web-application framework that includes everything needed to create |
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4 | database-backed web applications according to the Model-View-Control pattern. |
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5 | |
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6 | This pattern splits the view (also called the presentation) into "dumb" templates |
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7 | that are primarily responsible for inserting pre-built data in between HTML tags. |
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8 | The model contains the "smart" domain objects (such as Account, Product, Person, |
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9 | Post) that holds all the business logic and knows how to persist themselves to |
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10 | a database. The controller handles the incoming requests (such as Save New Account, |
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11 | Update Product, Show Post) by manipulating the model and directing data to the view. |
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12 | |
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13 | In Rails, the model is handled by what's called an object-relational mapping |
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14 | layer entitled Active Record. This layer allows you to present the data from |
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15 | database rows as objects and embellish these data objects with business logic |
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16 | methods. You can read more about Active Record in |
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17 | link:files/vendor/rails/activerecord/README.html. |
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18 | |
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19 | The controller and view are handled by the Action Pack, which handles both |
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20 | layers by its two parts: Action View and Action Controller. These two layers |
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21 | are bundled in a single package due to their heavy interdependence. This is |
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22 | unlike the relationship between the Active Record and Action Pack that is much |
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23 | more separate. Each of these packages can be used independently outside of |
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24 | Rails. You can read more about Action Pack in |
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25 | link:files/vendor/rails/actionpack/README.html. |
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26 | |
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27 | |
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28 | == Getting Started |
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29 | |
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30 | 1. At the command prompt, start a new Rails application using the <tt>rails</tt> command |
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31 | and your application name. Ex: rails myapp |
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32 | 2. Change directory into myapp and start the web server: <tt>script/server</tt> (run with --help for options) |
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33 | 3. Go to http://localhost:3000/ and get "Welcome aboard: You're riding the Rails!" |
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34 | 4. Follow the guidelines to start developing your application |
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35 | |
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36 | |
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37 | == Web Servers |
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38 | |
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39 | By default, Rails will try to use Mongrel if it's are installed when started with script/server, otherwise Rails will use WEBrick, the webserver that ships with Ruby. But you can also use Rails |
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40 | with a variety of other web servers. |
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41 | |
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42 | Mongrel is a Ruby-based webserver with a C component (which requires compilation) that is |
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43 | suitable for development and deployment of Rails applications. If you have Ruby Gems installed, |
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44 | getting up and running with mongrel is as easy as: <tt>gem install mongrel</tt>. |
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45 | More info at: http://mongrel.rubyforge.org |
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46 | |
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47 | Say other Ruby web servers like Thin and Ebb or regular web servers like Apache or LiteSpeed or |
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48 | Lighttpd or IIS. The Ruby web servers are run through Rack and the latter can either be setup to use |
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49 | FCGI or proxy to a pack of Mongrels/Thin/Ebb servers. |
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50 | |
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51 | == Apache .htaccess example for FCGI/CGI |
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52 | |
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53 | # General Apache options |
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54 | AddHandler fastcgi-script .fcgi |
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55 | AddHandler cgi-script .cgi |
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56 | Options +FollowSymLinks +ExecCGI |
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57 | |
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58 | # If you don't want Rails to look in certain directories, |
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59 | # use the following rewrite rules so that Apache won't rewrite certain requests |
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60 | # |
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61 | # Example: |
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62 | # RewriteCond %{REQUEST_URI} ^/notrails.* |
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63 | # RewriteRule .* - [L] |
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64 | |
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65 | # Redirect all requests not available on the filesystem to Rails |
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66 | # By default the cgi dispatcher is used which is very slow |
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67 | # |
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68 | # For better performance replace the dispatcher with the fastcgi one |
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69 | # |
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70 | # Example: |
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71 | # RewriteRule ^(.*)$ dispatch.fcgi [QSA,L] |
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72 | RewriteEngine On |
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73 | |
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74 | # If your Rails application is accessed via an Alias directive, |
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75 | # then you MUST also set the RewriteBase in this htaccess file. |
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76 | # |
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77 | # Example: |
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78 | # Alias /myrailsapp /path/to/myrailsapp/public |
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79 | # RewriteBase /myrailsapp |
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80 | |
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81 | RewriteRule ^$ index.html [QSA] |
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82 | RewriteRule ^([^.]+)$ $1.html [QSA] |
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83 | RewriteCond %{REQUEST_FILENAME} !-f |
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84 | RewriteRule ^(.*)$ dispatch.cgi [QSA,L] |
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85 | |
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86 | # In case Rails experiences terminal errors |
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87 | # Instead of displaying this message you can supply a file here which will be rendered instead |
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88 | # |
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89 | # Example: |
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90 | # ErrorDocument 500 /500.html |
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91 | |
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92 | ErrorDocument 500 "<h2>Application error</h2>Rails application failed to start properly" |
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93 | |
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94 | |
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95 | == Debugging Rails |
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96 | |
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97 | Sometimes your application goes wrong. Fortunately there are a lot of tools that |
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98 | will help you debug it and get it back on the rails. |
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99 | |
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100 | First area to check is the application log files. Have "tail -f" commands running |
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101 | on the server.log and development.log. Rails will automatically display debugging |
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102 | and runtime information to these files. Debugging info will also be shown in the |
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103 | browser on requests from 127.0.0.1. |
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104 | |
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105 | You can also log your own messages directly into the log file from your code using |
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106 | the Ruby logger class from inside your controllers. Example: |
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107 | |
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108 | class WeblogController < ActionController::Base |
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109 | def destroy |
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110 | @weblog = Weblog.find(params[:id]) |
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111 | @weblog.destroy |
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112 | logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!") |
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113 | end |
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114 | end |
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115 | |
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116 | The result will be a message in your log file along the lines of: |
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117 | |
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118 | Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1 |
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119 | |
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120 | More information on how to use the logger is at http://www.ruby-doc.org/core/ |
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121 | |
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122 | Also, Ruby documentation can be found at http://www.ruby-lang.org/ including: |
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123 | |
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124 | * The Learning Ruby (Pickaxe) Book: http://www.ruby-doc.org/docs/ProgrammingRuby/ |
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125 | * Learn to Program: http://pine.fm/LearnToProgram/ (a beginners guide) |
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126 | |
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127 | These two online (and free) books will bring you up to speed on the Ruby language |
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128 | and also on programming in general. |
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129 | |
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130 | |
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131 | == Debugger |
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132 | |
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133 | Debugger support is available through the debugger command when you start your Mongrel or |
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134 | Webrick server with --debugger. This means that you can break out of execution at any point |
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135 | in the code, investigate and change the model, AND then resume execution! |
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136 | You need to install ruby-debug to run the server in debugging mode. With gems, use 'gem install ruby-debug' |
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137 | Example: |
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138 | |
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139 | class WeblogController < ActionController::Base |
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140 | def index |
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141 | @posts = Post.find(:all) |
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142 | debugger |
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143 | end |
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144 | end |
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145 | |
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146 | So the controller will accept the action, run the first line, then present you |
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147 | with a IRB prompt in the server window. Here you can do things like: |
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148 | |
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149 | >> @posts.inspect |
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150 | => "[#<Post:0x14a6be8 @attributes={\"title\"=>nil, \"body\"=>nil, \"id\"=>\"1\"}>, |
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151 | #<Post:0x14a6620 @attributes={\"title\"=>\"Rails you know!\", \"body\"=>\"Only ten..\", \"id\"=>\"2\"}>]" |
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152 | >> @posts.first.title = "hello from a debugger" |
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153 | => "hello from a debugger" |
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154 | |
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155 | ...and even better is that you can examine how your runtime objects actually work: |
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156 | |
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157 | >> f = @posts.first |
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158 | => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}> |
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159 | >> f. |
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160 | Display all 152 possibilities? (y or n) |
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161 | |
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162 | Finally, when you're ready to resume execution, you enter "cont" |
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163 | |
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164 | |
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165 | == Console |
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166 | |
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167 | You can interact with the domain model by starting the console through <tt>script/console</tt>. |
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168 | Here you'll have all parts of the application configured, just like it is when the |
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169 | application is running. You can inspect domain models, change values, and save to the |
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170 | database. Starting the script without arguments will launch it in the development environment. |
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171 | Passing an argument will specify a different environment, like <tt>script/console production</tt>. |
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172 | |
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173 | To reload your controllers and models after launching the console run <tt>reload!</tt> |
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174 | |
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175 | == dbconsole |
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176 | |
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177 | You can go to the command line of your database directly through <tt>script/dbconsole</tt>. |
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178 | You would be connected to the database with the credentials defined in database.yml. |
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179 | Starting the script without arguments will connect you to the development database. Passing an |
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180 | argument will connect you to a different database, like <tt>script/dbconsole production</tt>. |
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181 | Currently works for mysql, postgresql and sqlite. |
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182 | |
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183 | == Description of Contents |
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184 | |
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185 | app |
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186 | Holds all the code that's specific to this particular application. |
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187 | |
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188 | app/controllers |
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189 | Holds controllers that should be named like weblogs_controller.rb for |
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190 | automated URL mapping. All controllers should descend from ApplicationController |
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191 | which itself descends from ActionController::Base. |
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192 | |
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193 | app/models |
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194 | Holds models that should be named like post.rb. |
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195 | Most models will descend from ActiveRecord::Base. |
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196 | |
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197 | app/views |
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198 | Holds the template files for the view that should be named like |
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199 | weblogs/index.html.erb for the WeblogsController#index action. All views use eRuby |
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200 | syntax. |
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201 | |
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202 | app/views/layouts |
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203 | Holds the template files for layouts to be used with views. This models the common |
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204 | header/footer method of wrapping views. In your views, define a layout using the |
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205 | <tt>layout :default</tt> and create a file named default.html.erb. Inside default.html.erb, |
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206 | call <% yield %> to render the view using this layout. |
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207 | |
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208 | app/helpers |
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209 | Holds view helpers that should be named like weblogs_helper.rb. These are generated |
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210 | for you automatically when using script/generate for controllers. Helpers can be used to |
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211 | wrap functionality for your views into methods. |
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212 | |
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213 | config |
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214 | Configuration files for the Rails environment, the routing map, the database, and other dependencies. |
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215 | |
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216 | db |
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217 | Contains the database schema in schema.rb. db/migrate contains all |
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218 | the sequence of Migrations for your schema. |
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219 | |
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220 | doc |
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221 | This directory is where your application documentation will be stored when generated |
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222 | using <tt>rake doc:app</tt> |
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223 | |
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224 | lib |
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225 | Application specific libraries. Basically, any kind of custom code that doesn't |
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226 | belong under controllers, models, or helpers. This directory is in the load path. |
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227 | |
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228 | public |
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229 | The directory available for the web server. Contains subdirectories for images, stylesheets, |
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230 | and javascripts. Also contains the dispatchers and the default HTML files. This should be |
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231 | set as the DOCUMENT_ROOT of your web server. |
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232 | |
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233 | script |
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234 | Helper scripts for automation and generation. |
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235 | |
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236 | test |
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237 | Unit and functional tests along with fixtures. When using the script/generate scripts, template |
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238 | test files will be generated for you and placed in this directory. |
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239 | |
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240 | vendor |
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241 | External libraries that the application depends on. Also includes the plugins subdirectory. |
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242 | If the app has frozen rails, those gems also go here, under vendor/rails/. |
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243 | This directory is in the load path. |
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