X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=catagits%2FCatalyst-Manual.git;a=blobdiff_plain;f=lib%2FCatalyst%2FManual%2FTutorial%2FBasicCRUD.pod;h=ac5261dfbdd4d00f118c9607312dcb369285c241;hp=0aa7e2ce96f591088d783bb75291838e369d16b3;hb=c16b23ababd7cc92688183b0c72480966a7876b4;hpb=994b66ad3ec2a66fb5d22957474229422b9ce110 diff --git a/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod b/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod index 0aa7e2c..ac5261d 100644 --- a/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod +++ b/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod @@ -209,10 +209,11 @@ Next, use your browser to enter the following URL: http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4 -Your browser should display "Added book 'TCPIP_Illustrated_Vol-2' by -'Stevens' with a rating of 5." along with a dump of the new book model -object. You should also see the following DBIC debug messages displayed -in the development server log messages if you have DBIC_TRACE set: +Your browser should display "Added book 'TCPIP_Illustrated_Vol-2' by +'Stevens' with a rating of 5." along with a dump of the new book model +object as it was returned by DBIC. You should also see the following +DBIC debug messages displayed in the development server log messages +if you have DBIC_TRACE set: INSERT INTO books (rating, title) VALUES (?, ?): `5', `TCPIP_Illustrated_Vol-2' INSERT INTO book_authors (author_id, book_id) VALUES (?, ?): `4', `6' @@ -342,47 +343,47 @@ initial version of the C method (the one using the C<:Local> attribute), you will notice that it produced output similar to the following: - [debug] Loaded Path actions: - .-------------------------------------+--------------------------------------. - | Path | Private | - +-------------------------------------+--------------------------------------+ - | / | /default | - | / | /index | - | /books | /books/index | - | /books/list | /books/list | - | /books/url_create | /books/url_create | - '-------------------------------------+--------------------------------------' + [debug] Loaded Path actions: + .-------------------------------------+--------------------------------------. + | Path | Private | + +-------------------------------------+--------------------------------------+ + | / | /default | + | / | /index | + | /books | /books/index | + | /books/list | /books/list | + | /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: - [debug] Loaded Path actions: - .-------------------------------------+--------------------------------------. - | Path | Private | - +-------------------------------------+--------------------------------------+ - | / | /default | - | / | /index | - | /books | /books/index | - | /books/list | /books/list | - '-------------------------------------+--------------------------------------' - - [debug] Loaded Chained actions: - .-------------------------------------+--------------------------------------. - | Path Spec | Private | - +-------------------------------------+--------------------------------------+ - | /books/url_create/*/*/* | /books/url_create | - '-------------------------------------+--------------------------------------' + [debug] Loaded Path actions: + .-------------------------------------+--------------------------------------. + | Path | Private | + +-------------------------------------+--------------------------------------+ + | / | /default | + | / | /index | + | /books | /books/index | + | /books/list | /books/list | + '-------------------------------------+--------------------------------------' + + [debug] Loaded Chained actions: + .-------------------------------------+--------------------------------------. + | Path Spec | Private | + +-------------------------------------+--------------------------------------+ + | /books/url_create/*/*/* | /books/url_create | + '-------------------------------------+--------------------------------------' C has disappeared form the "Loaded Path actions" section but it now shows up under the newly created "Loaded Chained actions" -section. And, the "/*/*/*" portion clearly shows that we have -specified that 3 arguments are required. +section. And, the "/*/*/*" portion clearly shows our requirement for +three arguments. As with our non-chained version of C, use your browser to enter the following URL: - http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4 + http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4 You should see the same "Added book 'TCPIP_Illustrated_Vol-2' by 'Stevens' with a rating of 5." along with a dump of the new book model @@ -397,28 +398,28 @@ little more of the power of chaining. First, open C in your editor and add the following 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::Books'); - - # Print a message to the debug log - $c->log->debug('*** INSIDE BASE METHOD ***'); - } - -Here we print a log message and store the resultset in + =head2 base + + Can place common logic to start chained dispatch here + + =cut + + sub base :Chained('/') :PathPart('books') :CaptureArgs(0) { + my ($self, $c) = @_; + + # Store the ResultSet in stash so it's available for other methods + $c->stash->{resultset} = $c->model('DB::Books'); + + # Print a message to the debug log + $c->log->debug('*** INSIDE BASE METHOD ***'); + } + +Here we print a log message and store the DBIC ResultSet in C<$c-Estash-E{resultset}> so that it's automatically available for other actions that chain off C. If your controller always needs a book ID as it's first argument, you could have the base method capture that argument (with C<:CaptureArgs(1)>) and use it to pull the -book object with that ID from the database and leave it in the stash for +book object with C<-Efind($id)> and leave it in the stash for later parts of your chains to then act upon. Because we have several actions that don't need to retrieve a book (such as the C we are working with now), we will instead add that functionality @@ -430,30 +431,30 @@ C to match the following: sub url_create :Chained('base') :PathPart('url_create') :Args(3) { -Next, let's try out our refactored chain. Restart the development -server and notice that our "Loaded Chained actions" section has -changed slightly: - - [debug] Loaded Chained actions: - .-------------------------------------+--------------------------------------. - | Path Spec | Private | - +-------------------------------------+--------------------------------------+ - | /books/url_create/*/*/* | /books/base (0) | - | | => /books/url_create | - '-------------------------------------+--------------------------------------' +Next, try out the refactored chain by restarting the development +server. Notice that our "Loaded Chained actions" section has changed +slightly: + + [debug] Loaded Chained actions: + .-------------------------------------+--------------------------------------. + | Path Spec | Private | + +-------------------------------------+--------------------------------------+ + | /books/url_create/*/*/* | /books/base (0) | + | | => /books/url_create | + '-------------------------------------+--------------------------------------' The "Path Spec" is the same, but now it maps to two Private actions as we would expect. Once again, enter the following URL into your browser: - http://localhost:3000/books/url_create/TCPIP_Illustrated_Vol-2/5/4 + 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." and dump of the new book object should appear. Also -notice the extra debug message in the development server output from -the C method. Click the "Return to list" link, you should find -that there are now eight books shown. +rating of 5" message and dump of the new book object should appear. +Also notice the extra debug message in the development server output +from the C method. Click the "Return to list" link, you should +find that there are now eight books shown. =head1 MANUALLY BUILDING A CREATE FORM @@ -552,17 +553,17 @@ it. Then restart the server: Notice that the server startup log reflects the two new chained methods that we added: - [debug] Loaded Chained actions: - .-------------------------------------+--------------------------------------. - | Path Spec | Private | - +-------------------------------------+--------------------------------------+ - | /books/form_create | /books/base (0) | - | | => /books/form_create | - | /books/form_create_do | /books/base (0) | - | | => /books/form_create_do | - | /books/url_create/*/*/* | /books/base (0) | - | | => /books/url_create | - '-------------------------------------+--------------------------------------' + [debug] Loaded Chained actions: + .-------------------------------------+--------------------------------------. + | Path Spec | Private | + +-------------------------------------+--------------------------------------+ + | /books/form_create | /books/base (0) | + | | => /books/form_create | + | /books/form_create_do | /books/base (0) | + | | => /books/form_create_do | + | /books/url_create/*/*/* | /books/base (0) | + | | => /books/url_create | + '-------------------------------------+--------------------------------------' Point your browser to L and enter "TCP/IP Illustrated, Vol 3" for the title, a rating of 5, and an @@ -584,7 +585,7 @@ from the database. =head2 Include a Delete Link in the List -Edit C and update it to the following (two +Edit C and update it to match the following (two sections have changed: 1) the additional 'Links' table header, and 2) the four lines for the Delete link near the bottom). @@ -620,7 +621,7 @@ and 2) the four lines for the Delete link near the bottom). [% # Add a link to delete a book %] - Delete + Delete [% END -%] @@ -630,32 +631,64 @@ The additional code is obviously designed to add a new column to the right side of the table with a C "button" (for simplicity, links will be used instead of full HTML buttons). -B You should use more than just a simple link with your -applications. Consider using some sort of of confirmation page -(typically with unique actions in your controller for both the -confirmation and the actual delete operation). Also, you should try -to use an HTTP POST operation (versus the GET used here) for -operations that change the state of your application (e.g., the -database). +Also notice that we are using a more advanced form of C than +we have seen before. Here we use C<$c-Econtroller- +Eaction_for> to automatically generate a URI appropriate for that +action based on the method we want to link to while inserting the +C value into the appropriate place. Now, if you ever change +C<:PathPart('delete')> in your controller method to +C<:PathPart('kill')>, then your links will automatically update +without any changes to your .tt2 template file. As long as the name +of your method does not changed ("delete" here), then your links will +still be correct. There are a few shortcuts and options when using +C: + +=over 4 + +=item * + +If you are referring to a method in the current controller, you can +use C<$self-Eaction_for('_method_name_')>. + +=item * + +If you are referring to a method in a different controller, you need +to include that controller's name as an argument to C, as in +C<$c-Econtroller('_controller_name_')-Eaction_for('_method_name_')>. + +=back + +B In practice you should B use a GET request to delete a +record -- always use POST for actions that will modify data. We are +doing it here for illustrative and simplicity purposes only. =head2 Add a Common Method to Retrieve a Book for the Chain -As mentioned earlier, since we have a mixture of actions that operate on -a single book ID and others that do no, we should not have C +As mentioned earlier, since we have a mixture of actions that operate +on a single book ID and others that do no, we should not have C capture the book ID, find the corresponding book in the database and save it in the stash for later links in the chain. However, just -because that logic does not belong in C doesn't mean that we can't -create another location to centralize that logic. In our case, we will -create a method called C that will store the specific book in -the stash. Chains that always operate on a single existing book can -chain off this method, but methods such as C that don't -operate on an existing book can chain directly off base. +because that logic does not belong in C doesn't mean that we +can't create another location to centralize the book lookup code. In +our case, we will create a method called C that will store the +specific book in the stash. Chains that always operate on a single +existing book can chain off this method, but methods such as +C that don't operate on an existing book can chain +directly off base. To add the C method, edit C 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 @@ -683,7 +716,7 @@ or as a hashref: $c->stash({object => $c->stash->{resultset}->find($id), another_thing => 1}); -Either format works, but the C<$c-Estash(name => value);> +Either format works, but the C<$c-Estash(name =E value);> style is growing in popularity -- you may which to use it all the time (even when you are only setting a single value). @@ -700,7 +733,6 @@ following method: =cut sub delete :Chained('object') :PathPart('delete') :Args(0) { - # $id = primary key of book to delete my ($self, $c) = @_; # Use the book object saved by 'object' and delete it along @@ -716,8 +748,7 @@ following method: This method first deletes the book object saved by the C method. However, it also removes the corresponding entry from the -C table. Note that C will cascade to also delete -the related join table entries in C. +C table with a cascading delete. Then, rather than forwarding to a "delete done" page as we did with the earlier create example, it simply sets the C to display a @@ -740,7 +771,7 @@ it. Then restart the server: The C method now appears in the "Loaded Chained actions" section of the startup debug output: - [debug] Loaded Chained actions: + [debug] Loaded Chained actions: .-------------------------------------+--------------------------------------. | Path Spec | Private | +-------------------------------------+--------------------------------------+ @@ -773,9 +804,11 @@ prior step -- it is still referencing the delete action: http://localhost:3000/books/delete/6 -What if the user were to press reload with this URL still active? In -this case the redundant delete is harmless, but in other cases this -could clearly be extremely dangerous. +What if the user were to press reload with this URL still active? In +this case the redundant delete is harmless (although it does generate +an exception screen, it doesn't perform any undesirable actions on the +application or database), but in other cases this could clearly be +extremely dangerous. We can improve the logic by converting to a redirect. Unlike C<$c-Eforward('list'))> or C<$c-Edetach('list'))> that perform @@ -795,8 +828,7 @@ C method to match: =cut sub delete :Chained('object') :PathPart('delete') :Args(0) { - # $id = primary key of book to delete - my ($self, $c, $id) = @_; + my ($self, $c) = @_; # Use the book object saved by 'object' and delete it along # with related 'book_authors' entries @@ -805,8 +837,9 @@ C method to match: # 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 - $c->response->redirect($c->uri_for('/books/list')); + # 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'))); } @@ -840,15 +873,14 @@ method to match the following: =cut sub delete :Chained('object') :PathPart('delete') :Args(0) { - # $id = primary key of book to delete - my ($self, $c, $id) = @_; + my ($self, $c) = @_; # Use the book object saved by 'object' and delete it along # with related 'book_authors' 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('/books/list', + $c->response->redirect($c->uri_for($self->action_for('list'), {status_msg => "Book deleted."})); } @@ -896,6 +928,461 @@ that should really go to Window A. For this reason, you may wish to use the "query param" technique shown here in your applications. +=head1 EXPLORING THE POWER OF DBIC + +In this section we will explore some additional capabilities offered +by DBIx::Class. Although these features have relatively little to do +with Catalyst per se, you will almost certainly want to take advantage +of them in your applications. + + +=head2 Convert to DBIC "load_namespaces" + +If you look back at +L you will recall that we load our DBIC Result Classes +(Books.pm, Authors.pm and BookAuthors.pm) with in +C with the C feature. Although +this method is perfectly valid, the DBIC community has migrated to a +newer C technique because it more easily supports a +variety of advanced features. Since we want to explore some of these +features below, let's first migrate our configuration over to use +C. + +If you are following along in Ubuntu 8.10, you will need to +upgrade your version of +L +to 0.23 or higher. To do this, we can install directly from CPAN: + + $ cpan Catalyst::Model::DBIC::Schema + +Then make sure you are running an appropriate version: + + $ perl -MCatalyst::Model::DBIC::Schema -e \ + 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"' + 0.23 + +Make sure you get version 0.22 or higher. + +B Ubuntu will automatically "do the right thing" and use the +module we installed from CPAN and ignore the older version we picked +up via the C command. If you are using a different +environment, you will need to make sure you are using v0.22 or higher +with the command above. + +While we are at it, let's install a few other modules from CPAN for +some of the other work we will be doing below: + + $ cpan Time::Warp DBICx::TestDatabase \ + DBIx::Class::DynamicDefault DBIx::Class::TimeStamp + +Next, we need to delete the existing C so that +the Catalyst DBIC helper will recreate it. Then we re-generate +the model and schema information: + + $ rm lib/MyApp/Schema.pm + $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \ + create=static components=TimeStamp dbi:SQLite:myapp.db + 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 ... + Schema dump completed. + exists "/root/dev/MyApp/script/../lib/MyApp/Model/DB.pm" + $ + $ ls lib/MyApp/Schema + Authors.pm BookAuthors.pm Books.pm Result + $ ls lib/MyApp/Schema/Result + Authors.pm BookAuthors.pm Books.pm + +Notice that we now have a duplicate set of Result Class files. With +the newer C feature, DBIC automatically looks for +your Result Class files in a subdirectory of the Schema directory +called C (the files in C were already there +from Part 3 of the tutorial; the files in C +are new). + +If you are using SQLite, you will need to manually re-enter the +relationship configuration as we did in Part 3 of the tutorial (if you +are using different database, the relationships might have been auto- +generated by Schema::Loader). One option is to use the following +command-line perl script to migrate the information across +automatically: + + $ cd lib/MyApp/Schema + $ perl -MIO::All -e 'for (@ARGV) { my $s < io($_); $s =~ s/.*\n\# You can replace.*?\n//s; + $s =~ s/'MyApp::Schema::/'MyApp::Schema::Result::/g; my $d < io("Result/$_"); + $d =~ s/1;\n?//; "$d$s" > io("Result/$_"); }' *.pm + $ cd ../../.. + +If you prefer, you can do the migration by hand using "cut and paste" +from the files in C (or from +L) +to the corresponding files in C. If you take +this approach, be sure to add C<::Result> to the end of +C in all three files (for example, in C, the +"peer class" in the C relationship needs to be changed from +C to C). + +Now we can remove the original set of Result Class files that we no +longer need: + + $ rm lib/MyApp/Schema/*.pm + $ ls lib/MyApp/Schema + Result + +Finally, test the application to be sure everything is still +working under our new configuration. Use the +C