creating_a_migration.step

goals {

  model_diagram header: 'Topics', fields: %w(id title description)

  message "The suggestotron has a list of topics that people can vote on. We'll store our topics in the database. In this step you'll do the following:"

  goal "Create a database table for topics with a title and a description"

  message "In this step we'll learn a bit about MVC (Model-View-Controller) architecture. By the end of this step you should understand the following concepts:"

  ul {
    li "A record"
    li "Model"
    li "View"
    li "Controller"
  }
}

steps {


  step {
    console "rails generate scaffold topic title:string description:text"
    message <<-MARKDOWN
* `generate scaffold` tells rails to create everything necessary to get up and running with topics.
* `topic` tells rails the name of the new model.
* `title:string` says that topics have a title, which is a string.
* `description:text` says that topics have a description which is a "text". (We're befuddled by the difference too.)
    MARKDOWN
    message "If you want, take some time to poke around the files listed in this step."
  }

  step {
    console "rake db:migrate"
    message "This tells rails to update the database to include a table for our new model."
  }
}

explanation {

  h2 "Rake"
  message <<-MARKDOWN
`rake` _(Ruby Make)_ is a tool that allows you to run small Ruby programs (**tasks**) that you use often in your application. Here, `rake db:migrate` is a task provided by the Rails framework.

You can run `rake -T` to see a list of all the `rake` commands your app currently responds to, along with a short description of each task.
  MARKDOWN

  h2 "Explaining MVC and Records"

  img src: "img/mvc.png", alt: "MVC"

  message "Rails implements a very specific notion of the **Model/View/Controller** pattern, which guides how you structure your web applications."

  h3 "Model"
  message <<-MARKDOWN
* saves data to the database
* accesses data from the database
* bridge between the database and objects
  MARKDOWN

  h3 "View"
  message <<-MARKDOWN
* display the data for human (or machine) consumption
* webpages are views
  MARKDOWN

  h3 "Controller"
  message <<-MARKDOWN
* acts as the glue between the models and the views
* combines data from multiple models
* summarizes and filters data
  MARKDOWN

  message <<-MARKDOWN
In MVC, models, views, and controllers have very specific jobs.  Separating responsibilities like this make it easy to maintain and extend rails applications.  When responsibilities become muddied it gets much harder to debug issues and add new functionality.
  MARKDOWN
}

next_step "CRUD_with_scaffolding"
Other Pages

creating_a_migration.step
