1. (Advanced) Web Application Development
Views in Rails Applications
Bruce Scharlau, University of Aberdeen, 2017

2. Discuss what you know about views with person next to you
Bruce Scharlau, University of Aberdeen, 2017

3. Bruce Scharlau, University of Aberdeen, 2017
MVC is a design pattern
Model
represents the data in the program and business logic
View (templates)
manages the visual display of the data (Presentation Logic)
Controller
provides the means for user interaction with the data (application logic)
Model
View
Controller
Bruce Scharlau, University of Aberdeen, 2017

4. A Rails request uses MVC
Browser
Model
Controller
View
The browser sends a request for a page to the controller on the server.
The controller retrieves the data it needs from the model in order to respond to the request.
The controller renders the data and sends it to the view.
The view sends the page back to the client for the browser to display.
Bruce Scharlau, University of Aberdeen, 2017

5. Keep domain logic out of views
The view is there to support the presentation of the model. Any Ruby code should be in the model, a helper, or in the controller.
Bruce Scharlau, University of Aberdeen, 2017

6. Views are generated for models
Show.html.erb displays a single recipe
Bruce Scharlau, University of Aberdeen, 2017

7. Views are generated for models
_form.html.erb is for ‘new’ and ‘edit’ recipe files
For loop gathers each attribute value of model
Bruce Scharlau, University of Aberdeen, 2017

8. Views are generated for models
index.html.erb is all recipe items
For loop goes through each item in array
Bruce Scharlau, University of Aberdeen, 2017

9. Explore Views built-in helpers
<%= text_area_tag(:message, "Hi, nice site", size: "24x6") %>
<%= password_field_tag(:password) %>
<%= hidden_field_tag(:parent_id, "5") %>
<%= search_field(:user, :name) %>
<%= telephone_field(:user, :phone) %>
<%= date_field(:user, :born_on) %>
<%= datetime_local_field(:user, :graduation_day) %>
<%= month_field(:user, :birthday_month) %>
<%= week_field(:user, :birthday_week) %>
<%= url_field(:user, :homepage) %>
<%= _field(:user, :address) %>
<%= color_field(:user, :favorite_color) %>
<%= time_field(:task, :started_at) %>
<%= number_field(:product, :price, in: , step: 0.5) %>
<%= range_field(:product, :discount, in: ) %>
Bruce Scharlau, University of Aberdeen, 2017

10. Form_for binds form to object
Bruce Scharlau, University of Aberdeen, 2017

11. Use ‘form_tag’ for regular forms
This is not tied to a model, so can gather data as required.
Bruce Scharlau, University of Aberdeen, 2017

12. Parameters are passed as array
Bruce Scharlau, University of Aberdeen, 2017

13. Use drop-down lists, etc as needed
We covered these in early practical sessions
Collection_select
Collection_radio_buttons
Bruce Scharlau, University of Aberdeen, 2017

14. Rails API pages offer options
Use API to find more options and details about how to use views
Bruce Scharlau, University of Aberdeen, 2017

15. Layouts are to be rendered
You can render the expected view by default. You can also change the rendered view. Instead of ‘show’ you could use ‘edit’ or something else as required.
Bruce Scharlau, University of Aberdeen, 2017

16. Render only headers if required
Pick option as needed to display result
Bruce Scharlau, University of Aberdeen, 2017

17. Render format as needed
You don’t have to return HTML. render render render html: "<strong>Not Found</strong>".html_safe render plain: “ok” render body: “raw”
When and why would you use these?
Bruce Scharlau, University of Aberdeen, 2017

18. Discuss two key points about views with person next to you
Bruce Scharlau, University of Aberdeen, 2017