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=1ae6394e5072386bb8c4ea34ad446f1e6c067c18;hp=72be8e15587ef8c513cf3c64ee77c5cf25e0cfa5;hb=554908172d7b73d43084ac283bb2dad6c7283e92;hpb=7edc54841a8a242568f86b548bf05ebe2400de80 diff --git a/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod b/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod index 72be8e1..1ae6394 100644 --- a/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod +++ b/lib/Catalyst/Manual/Tutorial/BasicCRUD.pod @@ -66,12 +66,12 @@ focus on the Create and Delete aspects of CRUD. More advanced capabilities, including full Update functionality, will be addressed in Part 9. -Although this part 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 +Although this part 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, -L, and +L, and L. You can checkout the source code for this example from the catalyst @@ -81,7 +81,7 @@ L. =head1 FORMLESS SUBMISSION -Our initial attempt at object creation will utilize the "URL +Our initial attempt at object creation will utilize the "URL arguments" feature of Catalyst (we will employ the more common form- based submission in the sections that follow). @@ -91,42 +91,42 @@ based submission in the sections that follow). Edit C and enter the following method: =head2 url_create - + Create a book with the supplied title, rating, and author - + =cut - + 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 "///model('DB::Books')->create({ title => $title, rating => $rating }); - - # Add a record to the join table for this book, mapping to + + # Add a record to the join table for this book, mapping to # appropriate author $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}); - + # Assign the Book object to the stash for display in the view $c->stash->{book} = $book; - + # This is a hack to disable XSUB processing in Data::Dumper # (it's used in the view). This is a work-around for a bug in # the interaction of some versions or Perl, Data::Dumper & DBIC. # You won't need this if you aren't using Data::Dumper (or if - # you are running DBIC 0.06001 or greater), but adding it doesn't + # you are running DBIC 0.06001 or greater), but adding it doesn't # hurt anything either. $Data::Dumper::Useperl = 1; - + # Set the TT template to use $c->stash->{template} = 'books/create_done.tt2'; } @@ -148,43 +148,43 @@ Edit C and then enter: [% # 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 on -%] [% # simple strings (e.g., no variable interpolation). -%] [% META title = 'Book Created' %] - + [% # Output information about the record that was added. First title. -%]

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.authors' from the DB once. -%] [% authors = book.authors %] [% # 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; + by '[% authors.first.last_name IF authors.first; authors.list.first.value.last_name IF ! authors.first %]' - + [% # Output the rating for the book that was added -%] with a rating of [% book.rating %].

- + [% # Provide a link back to the list page -%] [% # 'uri_for()' builds a full URI; e.g., 'http://localhost:3000/books/list' -%]

Return to list

- + [% # Try out the TT Dumper (for development only!) -%] 
     Dump of the 'book' variable:
     [% Dumper.dump(book) %]
-The TT C directive allows access to a variety of plugin modules -(TT plugins, that is, not Catalyst plugins) to add extra functionality -to the base TT capabilities. Here, the plugin allows -L "pretty printing" of objects and -variables. Other than that, the rest of the code should be familiar +The TT C directive allows access to a variety of plugin modules +(TT plugins, that is, not Catalyst plugins) to add extra functionality +to the base TT capabilities. Here, the plugin allows +L "pretty printing" of objects and +variables. Other than that, the rest of the code should be familiar from the examples in Part 3. @@ -209,34 +209,252 @@ 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 +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: +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' - SELECT author.id, author.first_name, author.last_name - FROM book_authors me JOIN authors author + SELECT author.id, author.first_name, author.last_name + FROM book_authors me JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '6' The C statements are obviously adding the book and linking it to the existing record for Richard Stevens. The C @@ -292,19 +510,19 @@ Edit C and add the following method to save the form information to the database: =head2 form_create_do - + Take information from form and add to database - + =cut - - sub form_create_do : Local { + + 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::Books')->create({ title => $title, @@ -312,14 +530,14 @@ save the form information to the database: }); # Handle relationship with author $book->add_to_book_authors({author_id => $author_id}); - + # Store new model object in stash $c->stash->{book} = $book; - + # Avoid Data::Dumper issue mentioned earlier - # You can probably omit this + # You can probably omit this $Data::Dumper::Useperl = 1; - + # Set the TT template to use $c->stash->{template} = 'books/create_done.tt2'; } @@ -332,6 +550,21 @@ it. Then restart the server: $ script/myapp_server.pl +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 | + '-------------------------------------+--------------------------------------' + Point your browser to L and enter "TCP/IP Illustrated, Vol 3" for the title, a rating of 5, and an author ID of 4. You should then see the output of the same @@ -352,7 +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). @@ -360,10 +593,10 @@ and 2) the four lines for the Delete link near the bottom). [% # 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 to root/lib/site/header -%] [% META title = 'Book List' -%] - + [% # Display each book in a table row %] @@ -374,11 +607,11 @@ and 2) the four lines for the Delete link near the bottom). [% END -%]
TitleRatingAuthor(s)Links
[% # 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 -%] + [% # 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 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. -%] + [% # 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. -%] [% tt_authors = [ ]; tt_authors.push(author.last_name) FOREACH author = book.authors %] [% # Now use a TT 'virtual method' to display the author count in parens -%] @@ -388,15 +621,104 @@ and 2) the four lines for the Delete link near the bottom). [% # Add a link to delete a book %] - Delete + Delete
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). +right side of the table with a C "button" (for simplicity, +links will be used instead of full HTML buttons). + +Also notice that we are using a more advanced form of C than +we have seen before. Here we use +C<$c-Econtroller-Eaction_for> to automatically generate a URI +appropriate for that action based on the method we want to link to +while inserting the C value into the appropriate place. Now, +if you ever change C<:PathPart('delete')> in your controller method to +C<:PathPart('kill')>, then your links will automatically update +without any changes to your .tt2 template file. As long as the name +of your method does not change ("delete" here), then your links will +still be correct. There are a few shortcuts and options when using +C: + +=over 4 + +=item * + +If you are referring to a method in the current controller, you can +use C<$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 not, 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 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 + $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}; + } + +Now, any other method that chains off C will automatically +have the appropriate book waiting for it in +C<$c-Estash-E{object}>. + +Also note that we are using different technique for setting +C<$c-Estash>. The advantage of this style is that it let's 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-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). =head2 Add a Delete Action to the Controller @@ -405,31 +727,28 @@ Open C in your editor and add the following method: =head2 delete - + Delete a book - + =cut - - sub delete : Local { - # $id = primary key of book to delete - my ($self, $c, $id) = @_; - - # Search for the book and then delete it - $c->model('DB::Books')->search({id => $id})->delete_all; - + + sub delete :Chained('object') :PathPart('delete') :Args(0) { + my ($self, $c) = @_; + + # Use the book object saved by 'object' and delete it along + # with related 'book_authors' 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'); } -This method first deletes the book with the specified primary key ID. +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 was used instead of -C: whereas C also removes the join table entries in -C, C does not (only use C if you -really need the cascading deletes... otherwise you are wasting resources). +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 @@ -447,24 +766,50 @@ equivalent. If the application is still running from before, use C to kill it. Then restart the server: - $ script/myapp_server.pl + $ DBIC_TRACE=1 script/myapp_server.pl + +The C method now appears in the "Loaded Chained actions" section +of the startup debug output: + + [debug] Loaded Chained actions: + .-------------------------------------+--------------------------------------. + | Path Spec | Private | + +-------------------------------------+--------------------------------------+ + | /books/id/*/delete | /books/base (0) | + | | -> /books/object (1) | + | | => /books/delete | + | /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 | + '-------------------------------------+--------------------------------------' Then point your browser to L and click -the "Delete" link next to the first "TCPIP_Illustrated_Vol-2". A green -"Book deleted" status message should display at the top of the page, -along with a list of the eight remaining books. +the "Delete" link next to the first "TCPIP_Illustrated_Vol-2". A green +"Book deleted" status message should display at the top of the page, +along with a list of the eight remaining books. You will also see the +cascading delete operation via the DBIC_TRACE output: + + SELECT me.id, me.title, me.rating FROM books me WHERE ( ( me.id = ? ) ): '6' + DELETE FROM books WHERE ( id = ? ): '6' + SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '6' + DELETE FROM book_authors WHERE ( author_id = ? AND book_id = ? ): '4', '6' =head2 Fixing a Dangerous URL -Note the URL in your browser once you have performed the deletion in the +Note the URL in your browser once you have performed the deletion in the prior step -- it is still referencing the delete action: - http://localhost:3000/books/delete/6 + http://localhost:3000/books/id/6/delete 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. +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 @@ -474,72 +819,75 @@ new request. As a result, the URL in the browser is updated to match the destination of the redirection URL. To convert the forward used in the previous section to a redirect, -open C and edit the existing +open C and edit the existing C method to match: - =head2 delete - + =head2 delete + Delete a book - + =cut - - sub delete : Local { - # $id = primary key of book to delete - my ($self, $c, $id) = @_; - - # Search for the book and then delete it - $c->model('DB::Books')->search({id => $id})->delete_all; - + + sub delete :Chained('object') :PathPart('delete') :Args(0) { + my ($self, $c) = @_; + + # Use the book object saved by 'object' and delete it along + # with related 'book_authors' 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 - $c->response->redirect($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'))); } =head2 Try the Delete and Redirect Logic -Restart the development server and point your browser to -L and delete the first copy of -"TCPIP_Illustrated_Vol-2". The URL in your browser should return to -the L URL, so that is an -improvement, but notice that I. Because the stash is reset on every request (and a -redirect involves a second request), the C is cleared -before it can be displayed. +Restart the development server and point your browser to +L (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 URL, so that is an +improvement, but notice that I. Because the stash is reset on every request (and a redirect +involves a second request), the C is cleared before it can +be displayed. =head2 Using C to Pass Query Parameters -There are several ways to pass information across a redirect. -In general, the best option is to use the C technique that we -will see in Part 5 of the tutorial; however, here we will pass the -information via query parameters on the redirect itself. Open -C and update the existing -C method to match the following: +There are several ways to pass information across a redirect. One +option is to use the C technique that we will see in Part 5 of +the tutorial; however, here we will pass the information via query +parameters on the redirect itself. Open +C and update the existing C +method to match the following: + + =head2 delete - =head2 delete - Delete a book - + =cut - - sub delete : Local { - # $id = primary key of book to delete - my ($self, $c, $id) = @_; - - # Search for the book and then delete it - $c->model('DB::Books')->search({id => $id})->delete_all; - + + sub delete :Chained('object') :PathPart('delete') :Args(0) { + my ($self, $c) = @_; + + # Use the book object saved by 'object' and delete it along + # with related 'book_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."})); } This modification simply leverages the ability of C to include -an arbitrary number of name/value pairs in a hash reference. Next, we -need to update C to handle C as a +an arbitrary number of name/value pairs in a hash reference. Next, we +need to update C to handle C as a query parameter: ... @@ -552,27 +900,497 @@ query parameter: ... -Although the sample above only shows the C div, leave the +Although the sample above only shows the C div, leave the rest of the file intact -- the only change we made to the C -was to add "C<|| c.request.params.status_msg>" to the +was to add "C<|| c.request.params.status_msg>" to the Cspan class="message"E> line. =head2 Try the Delete and Redirect With Query Param Logic -Restart the development server and point your browser to -L. Then delete the remaining copy -of "TCPIP_Illustrated_Vol-2". The green "Book deleted" status message +Restart the development server and point your browser to +L (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 Although this did present an opportunity to show a handy -capability of C, it would be much better to use Catalyst's -C feature in this situation. Although the technique here is -less dangerous than leaving the delete URL in the client's browser, -we have still exposed the status message to the user. With C, -this message returns to its rightful place as a service-side -mechanism (we will migrate this code to C in the next part -of the tutorial). +B Another popular method for maintaining server-side +information across a redirect is to use the C technique we +discuss in the next part of the tutorial, +L. While +C is a "slicker" mechanism in that it's all handled by the +server and doesn't "pollute" your URLs, B can lead to situations where the wrong information shows up +in the wrong browser window if the user has multiple windows or +browser tabs open.> For example, Window A causes something to be +placed in the stash, but before that window performs a redirect, +Window B makes a request to the server and gets the status information +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 Debian 5, you will need to upgrade your +version of +L to 0.23 +or higher. To do this, we can install directly from CPAN via the +following command: + + $ sudo 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 0.23 or higher. + +B Debian 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 v0.23 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