Difference between revisions of "Contribute: Plugins/ExportPluginsList"
(→Housekeeping) |
(→HelloList.pm) |
||
(24 intermediate revisions by 2 users not shown) | |||
Line 1: | Line 1: | ||
− | + | [[Category:Contribute]] | |
+ | [[Category:Plugins]] | ||
− | + | = Export Plugin Tutorial 2: List Handling = | |
− | + | In this tutorial you will learn to create a slightly more complex export plugin than the one created in [[Contribute:_Plugins/ExportPluginsHello| the previous tutorial]] that changes the way lists of eprints are exported. | |
− | The code in the section below should be placed in a file called HelloList.pm in the directory created previously | + | |
− | + | = HelloList.pm = | |
+ | The code in the section below should be placed in a file called HelloList.pm in the directory created previously. | ||
<pre> | <pre> | ||
package EPrints::Plugin::Export::MyPlugins::HelloList; | package EPrints::Plugin::Export::MyPlugins::HelloList; | ||
− | @ISA = ( | + | @ISA = ('EPrints::Plugin::Export'); |
use strict; | use strict; | ||
Line 20: | Line 22: | ||
my $self = $class->SUPER::new(%opts); | my $self = $class->SUPER::new(%opts); | ||
− | $self->{name} = | + | $self->{name} = 'Hello, List!'; |
$self->{accept} = [ 'dataobj/eprint', 'list/eprint' ]; | $self->{accept} = [ 'dataobj/eprint', 'list/eprint' ]; | ||
− | $self->{visible} = | + | $self->{visible} = 'all'; |
− | $self->{suffix} = | + | $self->{suffix} = '.txt'; |
− | $self->{mimetype} = | + | $self->{mimetype} = 'text/plain; charset=utf-8'; |
return $self; | return $self; | ||
Line 33: | Line 35: | ||
my ($plugin, $dataobj) = @_; | my ($plugin, $dataobj) = @_; | ||
− | return $dataobj->get_id()."\t".$dataobj->get_value( | + | return $dataobj->get_id()."\t".$dataobj->get_value('title')."\n"; |
} | } | ||
Line 40: | Line 42: | ||
my ($plugin, %opts) = @_; | my ($plugin, %opts) = @_; | ||
− | my $ | + | my $r = []; |
− | $ | + | my $header = "ID\tTitle\n\n"; |
+ | if (defined $opts{fh}) | ||
+ | { | ||
+ | print {$opts{fh}} $header; | ||
+ | } | ||
+ | else | ||
+ | { | ||
+ | push @{$r}, $header; | ||
+ | } | ||
− | foreach my $dataobj ($opts{ | + | foreach my $dataobj ($opts{list}->get_records) |
{ | { | ||
− | $ | + | my $part = $plugin->output_dataobj($dataobj, %opts); |
+ | if (defined $opts{fh}) | ||
+ | { | ||
+ | print {$opts{fh}} $part; | ||
+ | } | ||
+ | else | ||
+ | { | ||
+ | push @{$r}, $part; | ||
+ | } | ||
} | } | ||
− | return $ | + | if (defined $opts{fh}) |
+ | { | ||
+ | return undef; | ||
+ | } | ||
+ | return join('', @{$r}); | ||
} | } | ||
Line 55: | Line 77: | ||
</pre> | </pre> | ||
− | + | = In More Detail = | |
− | The above code is very similar to the HelloExport.pm file in [[ | + | The above code is very similar to the HelloExport.pm file in [[Contribute:_Plugins/ExportPluginsHello| the previous tutorial]] so only the points where it deviates significantly from that file will be discussed below. |
− | + | == Housekeeping == | |
The package name has been changed to reflect the filename. | The package name has been changed to reflect the filename. | ||
<pre> | <pre> | ||
− | package EPrints::Plugin::Export:: | + | package EPrints::Plugin::Export::MyPlugins::HelloList; |
</pre> | </pre> | ||
− | + | == Constructor == | |
Make sure you give each plugin a unique name. | Make sure you give each plugin a unique name. | ||
<pre> | <pre> | ||
− | $self->{name} = | + | $self->{name} = 'Hello, List!'; |
</pre> | </pre> | ||
− | + | == Dealing With Lists == | |
− | + | In this example the output_list method is overridden in the export plugin to provide column headers. The original method just concatenates the output from the output_dataobj subroutine called on every DataObj in the list. | |
− | |||
− | |||
− | |||
− | + | Note that the method is not provided with a bare array of DataObjs, but a List object is provided within the opts hash. To get an array of DataObjs to loop over you must then call that List object's get_record method. | |
− | + | == Filehandles == | |
+ | The command line export tool provides the output list method with a filehandle for output in the opts hash, while the [http://en.wikipedia.org/wiki/Common_Gateway_Interface CGI] export uses a value returned from the method. You must deal with the filehandle or you will get no output from the command line tool. In most cases this won't matter, but it is good practice to deal with it. | ||
− | + | The best way to handle output is to check if a filehandle has been provided every time something needs to be output. If a filehandle is provided we print to it, otherwise we save the output for later. At the end of the method we either return undef if a filehandle was provided or we return the saved output otherwise. | |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
<pre> | <pre> | ||
sub output_list | sub output_list | ||
Line 99: | Line 109: | ||
my ($plugin, %opts) = @_; | my ($plugin, %opts) = @_; | ||
− | my $ | + | my $r = []; |
− | $ | + | my $header = "ID\tTitle\n\n"; |
− | + | if (defined $opts{fh}) | |
− | + | { | |
+ | print {$opts{fh}} $header; | ||
+ | } | ||
+ | else | ||
{ | { | ||
− | $ | + | push @{$r}, $header; |
} | } | ||
− | + | foreach my $dataobj ($opts{list}->get_records) | |
{ | { | ||
− | print {$opts{ | + | my $part = $plugin->output_dataobj($dataobj, %opts); |
− | + | if (defined $opts{fh}) | |
+ | { | ||
+ | print {$opts{fh}} $part; | ||
+ | } | ||
+ | else | ||
+ | { | ||
+ | push @{$r}, $part; | ||
+ | } | ||
} | } | ||
− | + | ||
+ | if (defined $opts{fh}) | ||
{ | { | ||
− | return | + | return undef; |
} | } | ||
+ | return join('', @{$r}); | ||
} | } | ||
</pre> | </pre> | ||
+ | |||
+ | = Testing Your Plugin = | ||
+ | |||
+ | Restart your webserver and test the plugin as in [[Contribute:_Plugins/ExportPluginsHello| the previous tutorial]]. | ||
+ | |||
+ | == Sample Output == | ||
+ | [[Image:Explist.png]] |
Latest revision as of 11:59, 12 February 2010
Contents
Export Plugin Tutorial 2: List Handling
In this tutorial you will learn to create a slightly more complex export plugin than the one created in the previous tutorial that changes the way lists of eprints are exported.
HelloList.pm
The code in the section below should be placed in a file called HelloList.pm in the directory created previously.
package EPrints::Plugin::Export::MyPlugins::HelloList; @ISA = ('EPrints::Plugin::Export'); use strict; sub new { my ($class, %opts) = @_; my $self = $class->SUPER::new(%opts); $self->{name} = 'Hello, List!'; $self->{accept} = [ 'dataobj/eprint', 'list/eprint' ]; $self->{visible} = 'all'; $self->{suffix} = '.txt'; $self->{mimetype} = 'text/plain; charset=utf-8'; return $self; } sub output_dataobj { my ($plugin, $dataobj) = @_; return $dataobj->get_id()."\t".$dataobj->get_value('title')."\n"; } sub output_list { my ($plugin, %opts) = @_; my $r = []; my $header = "ID\tTitle\n\n"; if (defined $opts{fh}) { print {$opts{fh}} $header; } else { push @{$r}, $header; } foreach my $dataobj ($opts{list}->get_records) { my $part = $plugin->output_dataobj($dataobj, %opts); if (defined $opts{fh}) { print {$opts{fh}} $part; } else { push @{$r}, $part; } } if (defined $opts{fh}) { return undef; } return join('', @{$r}); } 1;
In More Detail
The above code is very similar to the HelloExport.pm file in the previous tutorial so only the points where it deviates significantly from that file will be discussed below.
Housekeeping
The package name has been changed to reflect the filename.
package EPrints::Plugin::Export::MyPlugins::HelloList;
Constructor
Make sure you give each plugin a unique name.
$self->{name} = 'Hello, List!';
Dealing With Lists
In this example the output_list method is overridden in the export plugin to provide column headers. The original method just concatenates the output from the output_dataobj subroutine called on every DataObj in the list.
Note that the method is not provided with a bare array of DataObjs, but a List object is provided within the opts hash. To get an array of DataObjs to loop over you must then call that List object's get_record method.
Filehandles
The command line export tool provides the output list method with a filehandle for output in the opts hash, while the CGI export uses a value returned from the method. You must deal with the filehandle or you will get no output from the command line tool. In most cases this won't matter, but it is good practice to deal with it.
The best way to handle output is to check if a filehandle has been provided every time something needs to be output. If a filehandle is provided we print to it, otherwise we save the output for later. At the end of the method we either return undef if a filehandle was provided or we return the saved output otherwise.
sub output_list { my ($plugin, %opts) = @_; my $r = []; my $header = "ID\tTitle\n\n"; if (defined $opts{fh}) { print {$opts{fh}} $header; } else { push @{$r}, $header; } foreach my $dataobj ($opts{list}->get_records) { my $part = $plugin->output_dataobj($dataobj, %opts); if (defined $opts{fh}) { print {$opts{fh}} $part; } else { push @{$r}, $part; } } if (defined $opts{fh}) { return undef; } return join('', @{$r}); }
Testing Your Plugin
Restart your webserver and test the plugin as in the previous tutorial.