Sessions exercise added

exercises/part1/ex11/step1.pl

@@ -0,0 +1,29 @@
+#!/usr/bin/perl
+use Dancer;
+use Data::Dump qw/pp/;
+
+set logger => 'console';
+set log => 'debug';
+set show_errors => 1;
+
+
+set engines => {
+    template_toolkit => 
+    {
+        start_tag => '[%',
+        stop_tag  => '%]'
+    }
+};
+set template  => 'template_toolkit';
+
+get '/' => sub {
+    my $ra_shopping_list = params->{item};
+    return template 'write-it-on-my-forehead' => { 
+      shopping_list => $ra_shopping_list ,
+      req_headers => pp(request->headers),
+    };
+};
+
+
+
+Dancer->dance;

exercises/part1/ex11/views/write-it-on-my-forehead.tt

@@ -0,0 +1,21 @@
+<h1>Shopping List on Forehead</h1>
+<form action="/" method="get">
+
+  Remember to buy: <input type="text" name="item" />
+  <input type="submit" value="Submit" />
+  <br/>
+  <br/>
+
+  <b> Don't forget </b><br/>
+  [% FOREACH item in shopping_list %]
+  <input type="text" name="item" value="[% item %]" readonly/> <br/>
+  [% END %]
+</form>
+
+
+
+
+<b> Headers: </b> <pre> [% req_headers %] </pre>
+
+
+

slides/part1.md

@@ -110,10 +110,13 @@ Finally,
 $ cp part1/ex1/step1.pl part1/ex1/step2-forward.pl
 ```
 
-and change the output to be a bit prettier using HTML tags:
+* change the output to be a bit prettier using HTML tags:
 
 ```<h1>Hello World!</h1>```
 
+* experiment with the ```debug``` function 
+for displaying information in the terminal.
+
 
 &raquo; Exercise 2: A non-index route
 ==============================
@@ -613,3 +616,60 @@ template 'hello-multiple-adj' => { adjective_list =>  params->{adjective} };
 ```
 
 What you'll have learnt from this is that multiple inputs of the same name are presented to the controller in an array ref of that name.
+
+
+Exercise 11: Magic Cookies and Sessions
+----------------------------------------
+
+In this exercise we'll be implementing a page for constructing a shopping
+list.  As a starting point, we've put the naive solution to this problem
+in your ```training.dancer.lpw.2011/exercises/part1/ex11``` directory as
+```step1.pl```
+
+Read the code and understand how the GET parameters are appended to the URL
+each time you add a new item to your shopping list.
+
+While this is very easy, there are a number of problems:
+ * Size limit - the maximum length of a url is 2048 characters in Internet Explorer 
+ * Privacy - Every internet server through which your request is managed can see what's in your shopping basket.
+ * Theft - You can add things to your basket just by modifying the url.
+
+The solution to these problems is based the concepts of 'cookie' and 'session'.
+
+* On a user's first HTTP request to the website,  a random string 
+(which we call a 
+<b>cookie</b>) is generated by the web server and is included in the HTTP 
+response header. On subsequent calls to this website, 
+your browser will send this cookie in the HTTP request header.
+
+* On receiving the user's cookie, the server uses it to retrieve any
+data it has stored in relation to this user. The continuity of visits
+to a website by a user, brought about by this data is referred 
+to as a <b>session</b>.
+
+
+<b>Task:</b> Copy ```step1.pl``` to ```step2.pl```, and 
+```views/write-it-on-my-forehead.tt``` to ```views/remember.tt``` 
+and change it to use cookies and sessions,
+so that each GET request only has the next item for the shopping list
+and previous items are stored in the session.
+
+<b>Hints:</b>
+* Near the top of ```step2.pl``` call ```set session => 'Simple'```
+* The command 
+```
+session shopping_list => $data 
+```
+stores ```$data``` in Dancer's internal hash of the form 
+``` $sessions{$cookie_id} = { shopping_list => $data } ```
+and there's no need to retrieve the cookie yourself.
+* The command
+```session('shopping_list')```
+returns any value saved against ```shopping_list``` in this session.
+* Because we're using Dancer::Session::Simple you can store
+any scalar against the ```shopping_list``` session key - even 
+a HashRef...
+
+
+
+

solutions/part1/ex11/step1.pl

@@ -0,0 +1,29 @@
+#!/usr/bin/perl
+use Dancer;
+use Data::Dump qw/pp/;
+
+set logger => 'console';
+set log => 'debug';
+set show_errors => 1;
+
+
+set engines => {
+    template_toolkit => 
+    {
+        start_tag => '[%',
+        stop_tag  => '%]'
+    }
+};
+set template  => 'template_toolkit';
+
+get '/' => sub {
+    my $ra_shopping_list = params->{item};
+    return template 'write-it-on-my-forehead' => { 
+      shopping_list => $ra_shopping_list ,
+      req_headers => pp(request->headers),
+    };
+};
+
+
+
+Dancer->dance;

solutions/part1/ex11/step2.pl

@@ -0,0 +1,40 @@
+#!/usr/bin/perl
+use Dancer;
+use Data::Dump qw/pp/;
+
+set logger => 'console';
+set log => 'debug';
+set show_errors => 1;
+set session => 'Simple';
+
+
+set engines => {
+    template_toolkit => 
+    {
+        start_tag => '[%',
+        stop_tag  => '%]'
+    }
+};
+set template  => 'template_toolkit';
+
+get '/' => sub {
+    debug ('Storing: '.pp(params->{item}));
+    my $one_item = params->{item};
+    my @items;
+    if (defined( session('shopping_list') )) {
+      @items = @{session('shopping_list') };
+    }
+    push @items, $one_item if $one_item;
+    session shopping_list => \@items;
+
+
+    return template 'remember' => { 
+      list => \@items , 
+      req_headers => pp(request->headers),
+    };
+
+};
+
+
+
+Dancer->dance;

solutions/part1/ex11/views/remember.tt

@@ -0,0 +1,28 @@
+<h1>Shopping List in Memory</h1>
+<form action="/" method="get">
+
+  Remember to buy: <input type="text" name="item" />
+  <input type="submit" value="Submit" />
+
+</form>
+
+  <br/>
+  <br/>
+
+<b> Don't forget </b><br/>
+<ul>
+  [% FOREACH item in list %]
+  <li>[% item %]</li>
+  [% END %]
+</ul>
+
+
+<br/>
+<br/>
+<br/>
+<br/>
+
+<b> Headers: </b> <pre> [% req_headers %] </pre>
+
+
+

solutions/part1/ex11/views/write-it-on-my-forehead.tt

@@ -0,0 +1,21 @@
+<h1>Shopping List on Forehead</h1>
+<form action="/" method="get">
+
+  Remember to buy: <input type="text" name="item" />
+  <input type="submit" value="Submit" />
+  <br/>
+  <br/>
+
+  <b> Don't forget </b><br/>
+  [% FOREACH item in shopping_list %]
+  <input type="text" name="item" value="[% item %]" readonly/> <br/>
+  [% END %]
+</form>
+
+
+
+
+<b> Headers: </b> <pre> [% req_headers %] </pre>
+
+
+