Although this chapter of the tutorial will show you how to build CRUD
functionality yourself, another option is to use a "CRUD builder" type
-of tool to automate the process. You get less control, but it's quick
-and easy. For example, see
-L<CatalystX::ListFramework::Builder|CatalystX::ListFramework::Builder>,
+of tool to automate the process. You get less control, but it can be
+quick and easy. For example, see
+L<Catalyst::Plugin::AutoCRUD|Catalyst::Plugin::AutoCRUD>,
L<CatalystX::CRUD|CatalystX::CRUD>, and
L<CatalystX::CRUD::YUI|CatalystX::CRUD::YUI>.
Edit C<lib/MyApp/Controller/Books.pm> and enter the following method:
=head2 url_create
-
+
Create a book with the supplied title, rating, and author
-
+
=cut
-
- sub url_create : Local {
+
+ sub url_create :Local {
# In addition to self & context, get the title, rating, &
# author_id args from the URL. Note that Catalyst automatically
# puts extra information after the "/<controller_name>/<action_name/"
- # into @_
+ # into @_. The args are separated by the '/' char on the URL.
my ($self, $c, $title, $rating, $author_id) = @_;
-
+
# Call create() on the book model object. Pass the table
# columns/field values we want to set as hash values
my $book = $c->model('DB::Book')->create({
title => $title,
rating => $rating
});
-
+
# Add a record to the join table for this book, mapping to
# appropriate author
- $book->add_to_book_author({author_id => $author_id});
+ $book->add_to_book_authors({author_id => $author_id});
# Note: Above is a shortcut for this:
- # $book->create_related('book_author', {author_id => $author_id});
-
- # Assign the Book object to the stash for display in the view
- $c->stash->{book} = $book;
-
- # Set the TT template to use
- $c->stash->{template} = 'books/create_done.tt2';
+ # $book->create_related('book_authors', {author_id => $author_id});
+
+ # Assign the Book object to the stash for display and set template
+ $c->stash(book => $book,
+ template => 'books/create_done.tt2');
}
Notice that Catalyst takes "extra slash-separated information" from the
URL and passes it as arguments in C<@_>. The C<url_create> action then
uses a simple call to the DBIC C<create> method to add the requested
information to the database (with a separate call to
-C<add_to_book_author> to update the join table). As do virtually all
+C<add_to_book_authors> to update the join table). As do virtually all
controller methods (at least the ones that directly handle user input),
it then sets the template that should handle this request.
[% # Not a good idea for production use, though. :-) 'Indent=1' is -%]
[% # optional, but prevents "massive indenting" of deeply nested objects -%]
[% USE Dumper(Indent=1) -%]
-
+
[% # Set the page title. META can 'go back' and set values in templates -%]
[% # that have been processed 'before' this template (here it's for -%]
[% # root/lib/site/html and root/lib/site/header). Note that META only -%]
[% # works on simple/static strings (i.e. there is no variable -%]
[% # interpolation). -%]
[% META title = 'Book Created' %]
-
- [% # Output information about the record that was added. First title. -%]
+
+ [% # Output information about the record that was added. First title. -%]
<p>Added book '[% book.title %]'
-
- [% # Output the last name of the first author. This is complicated by an -%]
- [% # issue in TT 2.15 where blessed hash objects are not handled right. -%]
- [% # First, fetch 'book.author' from the DB once. -%]
- [% authors = book.author %]
- [% # Now use IF statements to test if 'authors.first' is "working". If so, -%]
- [% # we use it. Otherwise we use a hack that seems to keep TT 2.15 happy. -%]
- by '[% authors.first.last_name IF authors.first;
- authors.list.first.value.last_name IF ! authors.first %]'
-
+
+ [% # Output the last name of the first author. -%]
+ by '[% book.authors.first.last_name %]'
+
[% # Output the rating for the book that was added -%]
with a rating of [% book.rating %].</p>
-
+
[% # Provide a link back to the list page -%]
[% # 'uri_for()' builds a full URI; e.g., 'http://localhost:3000/books/list' -%]
<p><a href="[% c.uri_for('/books/list') %]">Return to list</a></p>
-
+
[% # Try out the TT Dumper (for development only!) -%]
<pre>
Dump of the 'book' variable:
variables. Other than that, the rest of the code should be familiar
from the examples in Chapter 3.
+Note: If you are using TT v2.15 you will need to change the code that
+outputs the "last name for the first author" above to match this:
+
+ [% authors = book.authors %]
+ by '[% authors.first.last_name IF authors.first;
+ authors.list.first.value.last_name IF ! authors.first %]'
+
+to get around an issue in TT v2.15 where blessed hash objects were not
+handled correctly. But, if you are still using v2.15, it's probably
+time to upgrade (v2.15 is almost 4 years old). If you are following
+along in Debian, then you should be on at least v2.20. You can test
+your version of Template Toolkit with the following:
+
+ perl -MTemplate -e 'print "$Template::VERSION\n"'
+
=head2 Try the 'url_create' Feature
-If the application is still running from before, use C<Ctrl-C> to kill
-it. Then restart the server:
+Make sure the development server is running with the "-r" restart
+option:
- $ DBIC_TRACE=1 script/myapp_server.pl
+ $ DBIC_TRACE=1 script/myapp_server.pl -r
Note that new path for C</books/url_create> appears in the startup debug
output.
-B<TIP>: You can use C<script/myapp_server.pl -r> to have the development
-server auto-detect changed files and reload itself (if your browser acts
-odd, you should also try throwing in a C<-k>). If you make changes to
-the TT templates only, you do not need to reload the development server
-(only changes to "compiled code" such as Controller and Model C<.pm>
-files require a reload).
-
Next, use your browser to enter the following URL:
http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4
the existing record for Richard Stevens. The C<SELECT> statement results
from DBIC automatically fetching the book for the C<Dumper.dump(book)>.
-If you then click the "Return to list" link, you should find that
-there are now six books shown (if necessary, Shift+Reload or
-Ctrl+Reload your browser at the C</books/list> page). You should now see
-the following six DBIC debug messages displayed for N=1-6:
+If you then click the "Return to list" link, you should find that
+there are now six books shown (if necessary, Shift+Reload or
+Ctrl+Reload your browser at the C</books/list> page). You should now
+see the six DBIC debug messages similar to the following (where
+N=1-6):
- SELECT author.id, author.first_name, author.last_name \
- FROM book_author me JOIN author author \
- ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): 'N'
+ SELECT author.id, author.first_name, author.last_name
+ FROM book_author me JOIN author author
+ ON author.id = me.author_id WHERE ( me.book_id = ? ): 'N'
=head1 CONVERT TO A CHAINED ACTION
entered above to match the following:
sub url_create :Chained('/') :PathPart('books/url_create') :Args(3) {
+ # In addition to self & context, get the title, rating, &
+ # author_id args from the URL. Note that Catalyst automatically
+ # puts the first 3 arguments worth of extra information after the
+ # "/<controller_name>/<action_name/" into @_ because we specified
+ # "Args(3)". The args are separated by the '/' char on the URL.
+ my ($self, $c, $title, $rating, $author_id) = @_;
+
+ ...
This converts the method to take advantage of the Chained
action/dispatch type. Chaining lets you have a single URL
| /books/url_create | /books/url_create |
'-------------------------------------+--------------------------------------'
-Now start the development server with our basic chained method in
-place and the startup debug output should change to something along
-the lines of the following:
+When the development server restarts, the debug output should change
+to something along the lines of the following:
[debug] Loaded Path actions:
.-------------------------------------+--------------------------------------.
| /books | /books/index |
| /books/list | /books/list |
'-------------------------------------+--------------------------------------'
-
+
[debug] Loaded Chained actions:
.-------------------------------------+--------------------------------------.
| Path Spec | Private |
method:
=head2 base
-
+
Can place common logic to start chained dispatch here
-
+
=cut
-
+
sub base :Chained('/') :PathPart('books') :CaptureArgs(0) {
my ($self, $c) = @_;
-
+
# Store the ResultSet in stash so it's available for other methods
- $c->stash->{resultset} = $c->model('DB::Book');
-
+ $c->stash(resultset => $c->model('DB::Book'));
+
# Print a message to the debug log
$c->log->debug('*** INSIDE BASE METHOD ***');
}
sub url_create :Chained('base') :PathPart('url_create') :Args(3) {
-Next, try out the refactored chain by restarting the development
-server. Notice that our "Loaded Chained actions" section has changed
-slightly:
+Once you save C<lib/MyApp/Controller/Books.pm>, notice that the
+development server will restart and our "Loaded Chained actions" section
+will changed slightly:
[debug] Loaded Chained actions:
.-------------------------------------+--------------------------------------.
| | => /books/url_create |
'-------------------------------------+--------------------------------------'
-The "Path Spec" is the same, but now it maps to two Private actions as
-we would expect.
+The "Path Spec" is the same, but now it maps to two Private actions as
+we would expect. The C<base> method is being triggered by the
+C</books> part of the URL. However, the processing then continues to
+the C<url_create> method because this method "chained" off C<base> and
+specified C<:PathPart('url_create')> (note that we could have omitted
+the "PathPart" here because it matches the name of the method, but we
+will include it to make the logic as explicit as possible).
Once again, enter the following URL into your browser:
http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4
-The same "Added book 'TCPIP_Illustrated_Vol-2' by 'Stevens' with a
-rating of 5." message and a dump of the new book object should appear.
-Also notice the extra debug message in the development server output
-from the C<base> method. Click the "Return to list" link, and you
-should find that there are now eight books shown.
+The same "Added book 'TCPIP_Illustrated_Vol-2' by 'Stevens' with a
+rating of 5." message and a dump of the new book object should appear.
+Also notice the extra "INSIDE BASE METHOD" debug message in the
+development server output from the C<base> method. Click the "Return
+to list" link, and you should find that there are now eight books
+shown. (You may have a larger number of books if you repeated any of
+the "create" actions more than once. Don't worry about it as long as
+the number of books is appropriate for the number of times you added
+new books... there should be the original five books added via
+C<myapp01.sql> plus one additional book for each time you ran one
+of the url_create variations above.)
=head1 MANUALLY BUILDING A CREATE FORM
Edit C<lib/MyApp/Controller/Books.pm> and add the following method:
=head2 form_create
-
+
Display form to collect information for book to create
-
+
=cut
-
+
sub form_create :Chained('base') :PathPart('form_create') :Args(0) {
my ($self, $c) = @_;
-
+
# Set the TT template to use
- $c->stash->{template} = 'books/form_create.tt2';
+ $c->stash(template => 'books/form_create.tt2');
}
This action simply invokes a view containing a form to create a book.
Open C<root/src/books/form_create.tt2> in your editor and enter:
[% META title = 'Manual Form Book Create' -%]
-
+
<form method="post" action="[% c.uri_for('form_create_do') %]">
<table>
<tr><td>Title:</td><td><input type="text" name="title"></td></tr>
save the form information to the database:
=head2 form_create_do
-
+
Take information from form and add to database
-
+
=cut
-
+
sub form_create_do :Chained('base') :PathPart('form_create_do') :Args(0) {
my ($self, $c) = @_;
-
+
# Retrieve the values from the form
my $title = $c->request->params->{title} || 'N/A';
my $rating = $c->request->params->{rating} || 'N/A';
my $author_id = $c->request->params->{author_id} || '1';
-
+
# Create the book
my $book = $c->model('DB::Book')->create({
title => $title,
rating => $rating,
});
# Handle relationship with author
- $book->add_to_book_author({author_id => $author_id});
-
- # Store new model object in stash
- $c->stash->{book} = $book;
-
+ $book->add_to_book_authors({author_id => $author_id});
+ # Note: Above is a shortcut for this:
+ # $book->create_related('book_authors', {author_id => $author_id});
+
# Avoid Data::Dumper issue mentioned earlier
# You can probably omit this
$Data::Dumper::Useperl = 1;
-
- # Set the TT template to use
- $c->stash->{template} = 'books/create_done.tt2';
+
+ # Store new model object in stash and set template
+ $c->stash(book => $book,
+ template => 'books/create_done.tt2');
}
=head2 Test Out The Form
-If the application is still running from before, use C<Ctrl-C> to kill
-it. Then restart the server:
-
- $ script/myapp_server.pl
-
Notice that the server startup log reflects the two new chained
methods that we added:
"Return to list" to view the full list of books.
B<Note:> Having the user enter the primary key ID for the author is
-obviously crude; we will address this concern with a drop-down list in
-Chapter 9.
+obviously crude; we will address this concern with a drop-down list and
+add validation to our forms in Chapter 9.
=head1 A SIMPLE DELETE FEATURE
[% # see this "chomping" in your browser because HTML ignores blank lines, but -%]
[% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
[%- # optional, but both the beginning and the ending TT tags support chomping. -%]
-
+
[% # Provide a title -%]
[% META title = 'Book List' -%]
-
+
<table>
<tr><th>Title</th><th>Rating</th><th>Author(s)</th><th>Links</th></tr>
[% # Display each book in a table row %]
<td>[% book.title %]</td>
<td>[% book.rating %]</td>
<td>
+ [% # NOTE: See "Exploring The Power of DBIC" for a better way to do this! -%]
[% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
[% # loop in 'side effect notation' to load just the last names of the -%]
[% # authors into the list. Note that the 'push' TT vmethod doesn't return -%]
[% # a value, so nothing will be printed here. But, if you have something -%]
[% # in TT that does return a value and you don't want it printed, you can -%]
- [% # 1) assign it to a bogus value, or # 2) use the CALL keyword to -%]
- [% # call it and discard the return value. -%]
+ [% # 1) assign it to a bogus value, or -%]
+ [% # 2) use the CALL keyword to call it and discard the return value. -%]
[% tt_authors = [ ];
- tt_authors.push(author.last_name) FOREACH author = book.author %]
+ tt_authors.push(author.last_name) FOREACH author = book.authors %]
[% # Now use a TT 'virtual method' to display the author count in parens -%]
[% # Note the use of the TT filter "| html" to escape dangerous characters -%]
([% tt_authors.size | html %])
The additional code is obviously designed to add a new column to the
right side of the table with a C<Delete> "button" (for simplicity, links
will be used instead of full HTML buttons; in practice, anything that
-modifies data should be handled with a form sending a PUT request).
+modifies data should be handled with a form sending a POST request).
Also notice that we are using a more advanced form of C<uri_for> than
we have seen before. Here we use
and add the following code:
=head2 object
-
+
Fetch the specified book object based on the book ID and store
it in the stash
-
+
=cut
-
+
sub object :Chained('base') :PathPart('id') :CaptureArgs(1) {
# $id = primary key of book to delete
my ($self, $c, $id) = @_;
-
+
# Find the book object and store it in the stash
$c->stash(object => $c->stash->{resultset}->find($id));
-
+
# Make sure the lookup was successful. You would probably
# want to do something like this in a real app:
# $c->detach('/error_404') if !$c->stash->{object};
die "Book $id not found!" if !$c->stash->{object};
+
+ # Print a message to the debug log
+ $c->log->debug("*** INSIDE OBJECT METHOD for obj id=$id ***");
}
Now, any other method that chains off C<object> will automatically
have the appropriate book waiting for it in
C<$c-E<gt>stash-E<gt>{object}>.
-Also note that we are using a different technique for setting
-C<$c-E<gt>stash>. The advantage of this style is that it lets you set
-multiple stash variables at a time. For example:
-
- $c->stash(object => $c->stash->{resultset}->find($id),
- another_thing => 1);
-
-or as a hashref:
-
- $c->stash({object => $c->stash->{resultset}->find($id),
- another_thing => 1});
-
-Either format works, but the C<$c-E<gt>stash(name =E<gt> value);>
-style is growing in popularity -- you may wish to use it all
-the time (even when you are only setting a single value).
-
=head2 Add a Delete Action to the Controller
following method:
=head2 delete
-
+
Delete a book
-
+
=cut
-
+
sub delete :Chained('object') :PathPart('delete') :Args(0) {
my ($self, $c) = @_;
-
+
# Use the book object saved by 'object' and delete it along
# with related 'book_author' entries
$c->stash->{object}->delete;
-
+
# Set a status message to be displayed at the top of the view
$c->stash->{status_msg} = "Book deleted.";
-
+
# Forward to the list action/method in this controller
$c->forward('list');
}
=head2 Try the Delete Feature
-If the application is still running from before, use C<Ctrl-C> to kill
-it. Then restart the server:
-
- $ DBIC_TRACE=1 script/myapp_server.pl
-
-The C<delete> method now appears in the "Loaded Chained actions" section
+One you save the Books controller, the server should automatically restart.
+The C<delete> method should now appear in the "Loaded Chained actions" section
of the startup debug output:
[debug] Loaded Chained actions:
C<sub delete> method to match:
=head2 delete
-
+
Delete a book
-
+
=cut
-
+
sub delete :Chained('object') :PathPart('delete') :Args(0) {
my ($self, $c) = @_;
-
+
# Use the book object saved by 'object' and delete it along
# with related 'book_author' entries
$c->stash->{object}->delete;
-
+
# Set a status message to be displayed at the top of the view
$c->stash->{status_msg} = "Book deleted.";
-
+
# Redirect the user back to the list page. Note the use
# of $self->action_for as earlier in this section (BasicCRUD)
$c->response->redirect($c->uri_for($self->action_for('list')));
=head2 Try the Delete and Redirect Logic
-Restart the development server and point your browser to
-L<http://localhost:3000/books/list> (don't just hit "Refresh" in your
-browser since we left the URL in an invalid state in the previous
-section!) and delete the first copy of the remaining two
-"TCPIP_Illustrated_Vol-2" books. The URL in your browser should return
-to the L<http://localhost:3000/books/list> URL, so that is an
-improvement, but notice that I<no green "Book deleted" status message is
-displayed>. Because the stash is reset on every request (and a redirect
-involves a second request), the C<status_msg> is cleared before it can
-be displayed.
+Point your browser to L<http://localhost:3000/books/list> (don't just
+hit "Refresh" in your browser since we left the URL in an invalid state
+in the previous section!) and delete the first copy of the remaining two
+"TCPIP_Illustrated_Vol-2" books. The URL in your browser should return
+to the L<http://localhost:3000/books/list> URL, so that is an
+improvement, but notice that I<no green "Book deleted" status message is
+displayed>. Because the stash is reset on every request (and a redirect
+involves a second request), the C<status_msg> is cleared before it can
+be displayed.
=head2 Using 'uri_for' to Pass Query Parameters
method to match the following:
=head2 delete
-
+
Delete a book
-
+
=cut
-
+
sub delete :Chained('object') :PathPart('delete') :Args(0) {
my ($self, $c) = @_;
-
+
# Use the book object saved by 'object' and delete it along
# with related 'book_author' entries
$c->stash->{object}->delete;
-
+
# Redirect the user back to the list page with status msg as an arg
$c->response->redirect($c->uri_for($self->action_for('list'),
{status_msg => "Book deleted."}));
=head2 Try the Delete and Redirect With Query Param Logic
-Restart the development server and point your browser to
-L<http://localhost:3000/books/list> (you should now be able to safely
-hit "refresh" in your browser). Then delete the remaining copy of
-"TCPIP_Illustrated_Vol-2". The green "Book deleted" status message
-should return.
+Point your browser to L<http://localhost:3000/books/list> (you should
+now be able to safely hit "refresh" in your browser). Then delete the
+remaining copy of "TCPIP_Illustrated_Vol-2". The green "Book deleted"
+status message should return.
B<NOTE:> Another popular method for maintaining server-side
information across a redirect is to use the C<flash> technique we
sqlite> ALTER TABLE book ADD updated INTEGER;
sqlite> UPDATE book SET created = DATETIME('NOW'), updated = DATETIME('NOW');
sqlite> SELECT * FROM book;
- 1|CCSP SNRS Exam Certification Guide|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 2|TCP/IP Illustrated, Volume 1|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 3|Internetworking with TCP/IP Vol.1|4|2009-03-08 16:26:35|2009-03-08 16:26:35
- 4|Perl Cookbook|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 5|Designing with Web Standards|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 9|TCP/IP Illustrated, Vol 3|5|2009-03-08 16:26:35|2009-03-08 16:26:35
+ 1|CCSP SNRS Exam Certification Guide|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 2|TCP/IP Illustrated, Volume 1|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 3|Internetworking with TCP/IP Vol.1|4|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 4|Perl Cookbook|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 5|Designing with Web Standards|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 9|TCP/IP Illustrated, Vol 3|5|2010-02-16 04:15:45|2010-02-16 04:15:45
sqlite> .quit
$
with the new fields:
$ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
- create=static components=TimeStamp dbi:SQLite:myapp.db
+ create=static components=TimeStamp dbi:SQLite:myapp.db \
+ on_connect_do="PRAGMA foreign_keys = ON"
exists "/root/dev/MyApp/script/../lib/MyApp/Model"
exists "/root/dev/MyApp/script/../t"
Dumping manual schema for MyApp::Schema to directory /root/dev/MyApp/script/../lib ...
it to include the L<DBIx::Class::TimeStamp|DBIx::Class::TimeStamp>
in the C<load_components> line of the Result Classes.
-If you open C<lib/MyApp/Schema/Result/Book.pm> in your editor you
-should see that the C<created> and C<updated> fields are now included
-in the call to C<add_columns()>, but our relationship information below
-the "C<# DO NOT MODIFY...>" line was automatically preserved.
+If you open C<lib/MyApp/Schema/Result/Book.pm> in your editor you should
+see that the C<created> and C<updated> fields are now included in the
+call to C<add_columns()>. However, also notice that the C<many_to_many>
+relationships we manually added below the "C<# DO NOT MODIFY...>" line
+were automatically preserved.
While we have this file open, let's update it with some additional
information to have DBIC automatically handle the updating of these
update the timestamps in these columns whenever a row is created or
modified.
-To test this out, restart the development server using the
-C<DBIC_TRACE=1> option:
-
- DBIC_TRACE=1 script/myapp_server.pl
-
Then enter the following URL into your web browser:
http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4
you will see that the new book we added has an appropriate date and
time entered for it (see the last line in the listing below):
- sqlite3 myapp.db "select * from book"
- 1|CCSP SNRS Exam Certification Guide|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 2|TCP/IP Illustrated, Volume 1|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 3|Internetworking with TCP/IP Vol.1|4|2009-03-08 16:26:35|2009-03-08 16:26:35
- 4|Perl Cookbook|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 5|Designing with Web Standards|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 9|TCP/IP Illustrated, Vol 3|5|2009-03-08 16:26:35|2009-03-08 16:26:35
- 10|TCPIP_Illustrated_Vol-2|5|2009-03-08 16:29:08|2009-03-08 16:29:08
+ $ sqlite3 myapp.db "select * from book"
+ 1|CCSP SNRS Exam Certification Guide|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 2|TCP/IP Illustrated, Volume 1|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 3|Internetworking with TCP/IP Vol.1|4|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 4|Perl Cookbook|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 5|Designing with Web Standards|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 9|TCP/IP Illustrated, Vol 3|5|2010-02-16 04:15:45|2010-02-16 04:15:45
+ 10|TCPIP_Illustrated_Vol-2|5|2010-02-16 04:18:42|2010-02-16 04:18:42
Notice in the debug log that the SQL DBIC generated has changed to
incorporate the datetime logic:
- INSERT INTO book (created, rating, title, updated) VALUES (?, ?, ?, ?):
- '2009-03-08 16:29:08', '5', 'TCPIP_Illustrated_Vol-2', '2009-03-08 16:29:08'
- INSERT INTO book_author (author_id, book_id) VALUES (?, ?): '4', '10'
+ INSERT INTO book ( created, rating, title, updated ) VALUES ( ?, ?, ?, ? ):
+ '2010-02-16 04:18:42', '5', 'TCPIP_Illustrated_Vol-2', '2010-02-16 04:18:42'
+ INSERT INTO book_author ( author_id, book_id ) VALUES ( ?, ? ): '4', '10'
=head2 Create a ResultSet Class
method that returns books added in the last 10 minutes. Start by
making a directory where DBIx::Class will look for our ResultSet Class:
- mkdir lib/MyApp/Schema/ResultSet
+ $ mkdir lib/MyApp/Schema/ResultSet
Then open C<lib/MyApp/Schema/ResultSet/Book.pm> and enter the following:
package MyApp::Schema::ResultSet::Book;
-
+
use strict;
use warnings;
use base 'DBIx::Class::ResultSet';
-
+
=head2 created_after
-
+
A predefined search for recently added books
-
+
=cut
-
+
sub created_after {
my ($self, $datetime) = @_;
-
- my $date_str = $self->_source_handle->schema->storage
+
+ my $date_str = $self->result_source->schema->storage
->datetime_parser->format_datetime($datetime);
-
+
return $self->search({
created => { '>' => $date_str }
});
}
-
+
1;
-Then we need to tell the Result Class to to treat this as a ResultSet
-Class. Open C<lib/MyApp/Schema/Result/Book.pm> and add the following
-above the "C<1;>" at the bottom of the file:
-
- #
- # Set ResultSet Class
- #
- __PACKAGE__->resultset_class('MyApp::Schema::ResultSet::Book');
-
Then add the following method to the C<lib/MyApp/Controller/Books.pm>:
=head2 list_recent
-
+
List recently created books
-
+
=cut
-
+
sub list_recent :Chained('base') :PathPart('list_recent') :Args(1) {
my ($self, $c, $mins) = @_;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template, but only
# retrieve books created within the last $min number of minutes
- $c->stash->{books} = [$c->model('DB::Book')
- ->created_after(DateTime->now->subtract(minutes => $mins))];
-
+ $c->stash(books => [$c->model('DB::Book')
+ ->created_after(DateTime->now->subtract(minutes => $mins))]);
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
- $c->stash->{template} = 'books/list.tt2';
+ $c->stash(template => 'books/list.tt2');
}
-Now start the development server with C<DBIC_TRACE=1> and try
-different values for the minutes argument (the final number value) for
-the URL C<http://localhost:3000/books/list_recent/10>. For example,
-this would list all books added in the last fifteen minutes:
+Now try different values for the "minutes" argument (the final number
+value) using the URL C<http://localhost:3000/books/list_recent/_#_> in
+your browser. For example, this would list all books added in the last
+fifteen minutes:
http://localhost:3000/books/list_recent/15
C<lib/MyApp/Controller/Books.pm> and add the following method:
=head2 list_recent_tcp
-
+
List recently created books
-
+
=cut
-
+
sub list_recent_tcp :Chained('base') :PathPart('list_recent_tcp') :Args(1) {
my ($self, $c, $mins) = @_;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template, but only
# retrieve books created within the last $min number of minutes
# AND that have 'TCP' in the title
- $c->stash->{books} = [$c->model('DB::Book')
+ $c->stash(books => [$c->model('DB::Book')
->created_after(DateTime->now->subtract(minutes => $mins))
->search({title => {'like', '%TCP%'}})
- ];
-
+ ]);
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
- $c->stash->{template} = 'books/list.tt2';
+ $c->stash(template => 'books/list.tt2');
}
-To try this out, restart the development server with:
-
- DBIC_TRACE=1 script/myapp_server.pl
-
-And enter the following URL into your browser:
+To try this out, enter the following URL into your browser:
http://localhost:3000/books/list_recent_tcp/100
Take a look at the DBIC_TRACE output in the development server log for
the first URL and you should see something similar to the following:
- SELECT me.id, me.title, me.rating, me.created, me.updated FROM book me
- WHERE ( ( ( title LIKE ? ) AND ( created > ? ) ) ): '%TCP%', '2009-03-08 14:52:54'
+ SELECT me.id, me.title, me.rating, me.created, me.updated FROM book me
+ WHERE ( ( title LIKE ? AND created > ? ) ): '%TCP%', '2010-02-16 02:49:32'
However, let's not pollute our controller code with this raw "TCP"
query -- it would be cleaner to encapsulate that code in a method on
C<lib/MyApp/Schema/ResultSet/Book.pm> and add the following method:
=head2 title_like
-
+
A predefined search for books with a 'LIKE' search in the string
-
+
=cut
-
+
sub title_like {
my ($self, $title_str) = @_;
-
+
return $self->search({
title => { 'like' => "%$title_str%" }
});
shown here -- the rest of the method should be the same):
=head2 list_recent_tcp
-
+
List recently created books
-
+
=cut
-
+
sub list_recent_tcp :Chained('base') :PathPart('list_recent_tcp') :Args(1) {
my ($self, $c, $mins) = @_;
-
+
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template, but only
# retrieve books created within the last $min number of minutes
# AND that have 'TCP' in the title
- $c->stash->{books} = [$c->model('DB::Book')
+ $c->stash(books => [$c->model('DB::Book')
->created_after(DateTime->now->subtract(minutes => $mins))
->title_like('TCP')
- ];
-
+ ]);
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
- $c->stash->{template} = 'books/list.tt2';
+ $c->stash(template => 'books/list.tt2');
}
-Then restart the development server and try out the C<list_recent_tcp>
-and C<list_recent> URL as we did above. It should work just the same,
-but our code is obviously cleaner and more modular, while also being
-more flexible at the same time.
+Try out the C<list_recent_tcp> and C<list_recent> URLs as we did above.
+They should work just the same, but our code is obviously cleaner and
+more modular, while also being more flexible at the same time.
=head2 Adding Methods to Result Classes
#
sub full_name {
my ($self) = @_;
-
+
return $self->first_name . ' ' . $self->last_name;
}
...
[% tt_authors = [ ];
- tt_authors.push(author.last_name) FOREACH author = book.author %]
+ tt_authors.push(author.last_name) FOREACH author = book.authors %]
...
to:
...
[% tt_authors = [ ];
- tt_authors.push(author.full_name) FOREACH author = book.author %]
+ tt_authors.push(author.full_name) FOREACH author = book.authors %]
...
(Only C<author.last_name> was changed to C<author.full_name> -- the
rest of the file should remain the same.)
-Now restart the development server and go to the standard book list
-URL:
+Now go to the standard book list URL:
http://localhost:3000/books/list
The "Author(s)" column will now contain both the first and last name.
And, because the concatenation logic was encapsulated inside our
-Result Class, it keeps the code inside our .tt template nice and clean
+Result Class, it keeps the code inside our TT template nice and clean
(remember, we want the templates to be as close to pure HTML markup as
possible). Obviously, this capability becomes even more useful as you
use to to remove even more complicated row-specific logic from your
templates!
+=head2 Moving Complicated View Code to the Model
+
+The previous section illustrated how we could use a Result Class
+method to print the full names of the authors without adding any extra
+code to our view, but it still left us with a fairly ugly mess (see
+C<root/src/books/list.tt2>):
+
+ ...
+ <td>
+ [% # NOTE: See Chapter 4 for a better way to do this! -%]
+ [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
+ [% # loop in 'side effect notation' to load just the last names of the -%]
+ [% # authors into the list. Note that the 'push' TT vmethod does not print -%]
+ [% # a value, so nothing will be printed here. But, if you have something -%]
+ [% # in TT that does return a method and you don't want it printed, you -%]
+ [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%]
+ [% # call it and discard the return value. -%]
+ [% tt_authors = [ ];
+ tt_authors.push(author.full_name) FOREACH author = book.authors %]
+ [% # Now use a TT 'virtual method' to display the author count in parens -%]
+ [% # Note the use of the TT filter "| html" to escape dangerous characters -%]
+ ([% tt_authors.size | html %])
+ [% # Use another TT vmethod to join & print the names & comma separators -%]
+ [% tt_authors.join(', ') | html %]
+ </td>
+ ...
+
+Let's combine some of the techniques used earlier in this section to
+clean this up. First, let's add a method to our Book Result Class to
+return the number of authors for a book. Open
+C<lib/MyApp/Schema/Result/Book.pm> and add the following method:
+
+ =head2 author_count
+
+ Return the number of authors for the current book
+
+ =cut
+
+ sub author_count {
+ my ($self) = @_;
+
+ # Use the 'many_to_many' relationship to fetch all of the authors for the current
+ # and the 'count' method in DBIx::Class::ResultSet to get a SQL COUNT
+ return $self->authors->count;
+ }
+
+Next, let's add a method to return a list of authors for a book to the
+same C<lib/MyApp/Schema/Result/Book.pm> file:
+
+ =head2 author_list
+
+ Return a comma-separated list of authors for the current book
+
+ =cut
+
+ sub author_list {
+ my ($self) = @_;
+
+ # Loop through all authors for the current book, calling all the 'full_name'
+ # Result Class method for each
+ my @names;
+ foreach my $author ($self->authors) {
+ push(@names, $author->full_name);
+ }
+
+ return join(', ', @names);
+ }
+
+This method loops through each author, using the C<full_name> Result
+Class method we added to C<lib/MyApp/Schema/Result/Author.pm> in the
+prior section.
+
+Using these two methods, we can simplify our TT code. Open
+C<root/src/books/list.tt2> and update the "Author(s)" table cell to
+match the following:
+
+ ...
+ <td>
+ [% # Print count and author list using Result Class methods -%]
+ ([% book.author_count | html %]) [% book.author_list | html %]
+ </td>
+ ...
+
+Although most of the code we removed comprised comments, the overall
+effect is dramatic... because our view code is so simple, we don't need
+huge comments to clue people in to the gist of our code. The view code
+is now self-documenting and readable enough that you could probably get
+by with no comments at all. All of the "complex" work is being done in
+our Result Class methods (and, because we have broken the code into
+nice, modular chucks, the Result Class code is hardly something you
+would call complex).
+
+As we saw in this section, always strive to keep your view AND
+controller code as simple as possible by pulling code out into your
+model objects. Because DBIx::Class can be easily extended in so many
+ways, it's an excellent to way accomplish this objective. It will
+make your code cleaner, easier to write, less error-prone, and easier
+to debug and maintain.
+
+Before you conclude this section, hit Refresh in your browser... the
+output should be the same even though the backend code has been trimmed
+down.
+
+
=head1 AUTHOR
Kennedy Clark, C<hkclark@gmail.com>
Please report any errors, issues or suggestions to the author. The
most recent version of the Catalyst Tutorial can be found at
-L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
+L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
Copyright 2006-2008, Kennedy Clark, under Creative Commons License
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).
projects / catagits/Catalyst-Manual.git / blobdiff