Depot App Who Bought Enhancements


#1

I’ve completed the chapter on Internationalization successfully, but
found out just recently that the “Who Bought” function produces an
error page that looks very ugly when someone enters a product ID that
does not exist. My preference would be to design the app to have a
list of hyperlinks presented when you visit the URL,
http://localhost:3000/info/
that describes the list of “Info Functions” (eg “Who Bought” for
starters). Then when it takes you there,
http://localhost:3000/info/who_bought/
you would see a list of Book Titles as hyperlinks so that when you
click on a book title, it redirects you to the appropriate URL for
seeing a list of customers “who bought” that book. In this way I
could avoid the user’s temptation to use “non-existent” product ID’s
before it becomes a problem. But I have no idea how to go about
creating these features. I’m open to some ideas.

Arthur


#2

eengnerd wrote:

I’ve completed the chapter on Internationalization successfully, but
found out just recently that the “Who Bought” function produces an
error page that looks very ugly when someone enters a product ID that
does not exist. My preference would be to design the app to have a
list of hyperlinks presented when you visit the URL,
http://localhost:3000/info/
that describes the list of “Info Functions” (eg “Who Bought” for
starters). Then when it takes you there,
http://localhost:3000/info/who_bought/
you would see a list of Book Titles as hyperlinks so that when you
click on a book title, it redirects you to the appropriate URL for
seeing a list of customers “who bought” that book. In this way I
could avoid the user’s temptation to use “non-existent” product ID’s
before it becomes a problem. But I have no idea how to go about
creating these features. I’m open to some ideas.

Arthur

Sounds like the hard part is done, now it’s just coding…

So, where does …info/ go to?

You’ll need a view for that (info.html.erb?), and you’ll have to get
there somehow (think routes) via some controller (which to use… or
create?)

The list of book titles for ‘Who Bought’ smells an awful lot like a
generic book ‘index’ view, with maybe a twist on the rendering in the
erb.

If a book knows who bought it, listing the people who bought a book
smells like an adaptation of a book ‘show’ view.

Just get that info page working, then extend from there.


#3

To keep things simple for the moment, I created a file in /home/arthur/
RubySites/depot/app/views/info with a filename of index.html.erb and
put the following code into it:

Info Functions

Who Bought

Of course when you click this hyperlink, the file who_bought.html.erb
responds with:

ActiveRecord::RecordNotFound in InfoController#who_bought

Couldn’t find Product without an ID

So, my guess would be that I need to “test” for the condition where
the ID is missing and write some code in that file that loops through
the products table and creates hyperlinks such as:

Pragmatic
Project Automation

for each book title in the database.

I have to think about the syntax for all of that…any ideas?

Arthur

On Apr 16, 10:19 am, Ar Chron removed_email_address@domain.invalid


#4

I think I’m pretty close now. There are 3 files involved:

app/contollers/info_controller.rb which contains:

class InfoController < ApplicationController
def who_bought
if params[:id] == nil then
@products = Product.all
respond_to do |format|
format.html
format.xml { render :xml => @products }
end
else
@product = Product.find(params[:id])
@orders = @product.orders
respond_to do |format|
format.html
format.xml { render :layout => false , :xml => @product.to_xml
(:include => :orders) }
end
end
end
end

app/views/info/who_bought.html.erb which contains:

if @products != nil then
<% for product in @products %>
<a href=“http://localhost:3000/info/who_bought/”+<%=h product.id %>
+".html"><%=h product.title %>
<% end %>
else

People Who Bought <%= @product.title %>

    <% for order in @orders -%>
  • <%= mail_to order.email, order.name %>
  • <% end -%>
end

app/views/info/index.html.erb which contains:

Info Functions

Who Bought

The problem is that when I visit http://localhost:3000/info/who_bought/

I get the following error screen:

NoMethodError in Info#who_bought

Showing app/views/info/who_bought.html.erb where line #6 raised:

You have a nil object when you didn’t expect it!
The error occurred while evaluating nil.title

Extracted source (around line #6):

3: <a href=“http://localhost:3000/info/who_bought/”+<%=h
product.id %>+".html"><%=h product.title %>
4: <% end %>
5: else
6:

People Who Bought <%= @product.title %>


7:

    8: <% for order in @orders -%>
    9:
  • And I think I know why this is happening. I think that the if
    statement test in who_bought.html.erb is always causing the execution
    to fall into the else clause. My question is what test statement will
    give me what I want?

    Arthur

    On Apr 16, 10:19 am, Ar Chron removed_email_address@domain.invalid