9/23/15

To Lecture Notes

IT 231 -- 9/23/15

Review Questions

In a Rails scaffold project, why should you replace the coffee-script-source gem with version 1.8.0 rather than deleting the javascript_include_tag and csrf_meta_tags method calls on the layout page?
Ans: Because JavaScript is used in a scaffold project, for example, when deleting a row on the index view.
What does a one-to-many relationship do for you?
Ans: Consider the doctors (primary table) and patients (secondary table).
1. For each @patient object, you get a Doctor method that returns the Doctor object to which the patient belongs. Then you can get any field from that doctor that you need, for example @patient.doctor.name.
2. For each @doctor object, you get a patients array that contains all the patients that belong to the doctor. You can then loop over all these patients to display information about them, for example:
```
<% @doctor.patients.each do |p| %>
  <p>Name: <%= p.first_name %> <%= p.last_name %><br />
     Phone Number: <%= p.phone_number %></p>
<% end %>
```
Look at the Doctors controller source code. How are the @doctors instance variable used in the index view and the @doctor instance variable defined the show view defined?
Ans: Look in the index method of the Doctor controller. You see the line
```
@doctors = Doctor.all
```
This line uses the ActiveRecord method all to get an array of Doctor objects from the doctors table in the database. To obtain the @doctor object in the Doctor show view, look at the bottom of the Doctor controller. The set_doctor method uses the parameter id, which is obtained from the URL of the page. If the id is 5, the URL is
```
http://localhost:3000/doctors/5
```
The id is then obtained from
```
params[:id]
```
which is then used to look up the corresponding doctor in the database:
```
@doctor = Doctor.find(params[:id])
```
If you look at the top of the Doctor controller, the call back before_action calls the set_doctor method for the methods show, update, edit, and destroy.
Finish the Hospital1 Example. For the Patient new and edit views:
1. replace the textfield for entering the gender with a dropdown menu showing F and M,
2. replace the textfield for entering the doctor_id with a a dropdown menu that shows the doctors name but sends the corresponding doctor id to the database table.
On the Doctor index view, add a link to the Patient index view; on the Patient index view, add a link to the Doctor index view.

CSS file for Course Website

Here is the CSS file for the top level pages of the course website. These are the pages that have links in the address bar on the left.

Validations

A validation is used to insure that only data in the proper format is allowed to be entered into a database table.
A validation is called with the validates method in a model class.
Here are some Rails validations.

The File Field Control

The File Field Control is used for uploading files, including image files.
It is easy to place a File Field Control on a form (use the file_field helper method).
The hard part is managing the file after it is uploaded.
See the PetPhotoUpload Example.

Project 2

The goal of Project 2 is to create a scaffold project that will allow website users to upload photos and display them.
Look at the Project 2 Description.