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CatalystX-ListFramework-Builder-0.27
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/ CatalystX::ListFramework::Builder

NAME

CatalystX::ListFramework::Builder - Instant AJAX web front-end for DBIx::Class, using Catalyst

VERSION

This document refers to version 0.27 of CatalystX::ListFramework::Builder

WARNING

This is an ALPHA RELEASE. I'd really appreciate any bug reports; you can use the CPAN RT bug tracking system, or email me (Oliver) directly at the address at the bottom of this page. Please also be aware that the configuration file content has changed from previous releases of the module.

PURPOSE

You have a database schema available through DBIx::Class, and wish to have a basic web interface supporting Create, Retrieve, Update, Delete and Search, with little effort.

This module, with only a few lines of configuration, is able to create such interfaces on the fly. They are a bit whizzy and all Web 2.0-ish.

SYNOPSIS

A configuration file somewhere on your system:

 # [listframeworkuser.conf] in Config::General format
 
 extjs2   /javascript/extjs-2
 
 <Model::LFB::DBIC>
     schema_class   My::Database::Schema
     connect_info   dbi:Pg:dbname=mydbname;host=mydbhost.example.com;
     connect_info   username
     connect_info   password
     <connect_info>
         AutoCommit   1
     </connect_info>
 </Model::LFB::DBIC>

And in the CGI area of your web server:

 package ListFrameworkUser;
 use Catalyst qw(ConfigLoader +CatalystX::ListFramework::Builder);
 
 __PACKAGE__->setup;
 1;

Now going to the CGI area's URL will display a list of the tables in your database. Each item is a link to the web interface for that table.

DESCRIPTION

This module contains an application which will automatically construct a web interface for a database on the fly. The web interface supports Create, Retrieve, Update, Delete and Search operations.

The interface is not written to static files on your system, and uses AJAX to act upon the database without reloading your web page (much like other Web 2.0 appliactions, for example Google Mail).

The goals of the system are to require as little repetition of effort on your part as possible - the DRY principle (Don't Repeat Yourself). Almost all the information required is retrieved from the DBIx::Class ORM frontend to your database, which it is expected that you have already set up (although see "USAGE", below). This means that any change in database schema ought to be reflected immediately in the web interface after a page refresh.

USAGE

DBIx::Class setup

You will need DBIx::Class schema to be created and installed on your system. The recommended way to do this quickly is to use the excellent DBIx::Class::Schema::Loader module which connects to your database and writes DBIx::Class Perl modules for it.

Pick a suitable namespace for your schema, which is not related to this application. For example DBIC::Database::Foo::Schema for the Foo database. Then use the following command-line incantation:

 perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:. -e \
     'make_schema_at("DBIC::Database::Foo::Schema", { relationships => 1 }, \
     ["dbi:Pg:dbname=foodb;host=mydbhost.example.com","user","pass" ])'

This will create a directory (such as DBIC) which you need to move into your Perl Include path.

DBIx::Class helpers

When the web interface wants to display a column which references another table, you can make things look much better by adding a custom render method to your DBIx::Class Result Classes (i.e. the class files for each table).

First, the application will look for a method called display_name and use that. Here is an example which could be added to your Result Class files below the line which reads DO NOT MODIFY THIS OR ANYTHING ABOVE, and in this case returns the data from the title column:

 sub display_name {
     my $self = shift;
     return $self->title || '';
 }

Failing the existence of a display_name method, the application attempts to stringify the row object. Using stringification is not recommended, although some people like it. Here is an example of a stringification handler:

 use overload '""' => sub {
     my $self = shift;
     return $self->title || '';
 }, fallback => 1;

If all else fails the application prints the best hint it can to describe the foreign row. This is something approximating the name of the foreign table, the names of the primary keys, and associated values. It's better than stringifying the object the way Perl does, anyway.

One other very important tip: for those columns where your database uses an auto-incremented value, add the is_auto_increment => 1, option to the relevant hash in add_columns(). This will let the application know you don't need to supply a value for new or updated records. The interface will look much better as a result.

Finally, buried within one of the modules in this application are some filters, which are applied to data of certain types as it enters or leaves the database. If you find a particular data type is not being rendered correctly, please drop the author a line at the email address below, explaining what you'd like to see instead.

Download and install ExtJS

You'll need to download the ExtJS Javascript Library (version 2.2+ recommended), from this web page: http://extjs.com/products/extjs/download.php.

Install it to your web server in a location that it is able to serve as static content. Make a note of the path used in a URL to retrieve this content, as it will be needed in the application configuration file, below.

Application configuration file

Create the application configuration file, an example of which is below:

 extjs2   /javascript/extjs-2
 <Model::LFB::DBIC>
     schema_class   My::Database::Schema
     connect_info   dbi:Pg:dbname=mydbname;host=mydbhost.example.com;
     connect_info   username
     connect_info   password
     <connect_info>
         AutoCommit   1
     </connect_info>
 </Model::LFB::DBIC>

The Model::LFB::DBIC section must look (and be named) exactly like that above, except you should of course change the schema_class value and the values within connect_info.

The application needs to know where your copy of ExtJS is, on the web server. Use the extjs2 option as shown above to specify the URL path to the libraries. This will be used in the templates in some way like this:

 <script type="text/javascript" src="[% c.extjs2 %]/ext-all.js" />

Relocating LFB to another URL path

If you want to use this application as a plugin with another Catalyst system, it should work fine, but you probably want to serve pages under a different path on your web site. To do that, add the following to your configuration file:

 <Controller::LFB::Root>
     <action>
         <base>
             PathPart   admin
         </base>
     </action>
 </Controller::LFB::Root>

In the above example, the path .../admin/ will contain the LFB application, and all generated links in LFB will also make use of that path. Remember this is added to the base of your Cataylst application which, depending on your web server configuration, might also have a leading path.

Catalyst application

The final step is to write a very small file which allows this module to bootstrap a Catalyst application around your database. Locate on your web server the area where Perl content is executed, and create a file as below:

 package ListFrameworkUser;
 use Catalyst qw(ConfigLoader +CatalystX::ListFramework::Builder);
 
 __PACKAGE__->setup;
 1;

Let your web server know that this file is to be executed for any request which comes to its location.

If necessary, you'll need to let the ConfigLoader plugin know of the whereabouts of your application configuration file. See the Catalyst::Plugin::ConfigLoader documentation for more details, although here is a brief example of the change required:

 __PACKAGE__->config( 'Plugin::ConfigLoader' => { file => 'myapp.conf' } );
 __PACKAGE__->setup;

Accessing the application from your browser

Presumably the location of the Catalyst application created in the previous section maps to a particular URL path. Follow this path with the name of a table in the database, and you should be presented with a table of data. If you omit the table name, then the application prompts you with a list of the available tables.

EXAMPLES

There is an examples directory included with this distribution which includes the files necessary to set up a small demo application with SQLite3.

LIMITATIONS

Single column primary key

There's no support for multiple column primary keys (composite/compound keys). This has saved a lot of time in development because it greatly simplifies the Catalyst and DBIx::Class code.

No two columns in a given table may have the same FK constraint

If you have two columns which both have foreign key constraints to the same table, it's very likely LFB will not work. Again this is a simplification which speeded the initial development.

For the issues above, if you're desperate that the feature be implemented soon, please drop me a line at the address below, because you might be able to buy some of my time for the development.

REQUIREMENTS

  • ExtJS Javascript Library (version 2.2+ recommended), from http://extjs.com.

  • Catalyst::Runtime >= 5.70

  • Catalyst::Model::DBIC::Schema

  • Catalyst::View::JSON

  • Catalyst::View::TT

  • Catalyst::Action::RenderView

  • Class::C3

SEE ALSO

CatalystX::ListFramework is similar but has no dependency on Javascript (though it can use it for fancy auto-complete searches), and it also allows you to control which columns are rendered in the display.

ACKNOWLEDGEMENTS

Without the initial work on CatalystX::ListFramework by Andrew Payne and Peter Edwards this package would not exist. If you are looking for something like this module but without the dependency on Javascript, please do check out CatalystX::ListFramework.

AUTHOR

Oliver Gorwits <oliver.gorwits@oucs.ox.ac.uk>

COPYRIGHT & LICENSE

Bundled images are Copyright (c) 2006 Mark James, and are from http://www.famfamfam.com/lab/icons/silk/.

The rest is Copyright (c) Oliver Gorwits 2008. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under the terms of version 2 of the GNU General Public License as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA