Editing Contribute: Plugins/ImportPluginsCSV (section)

=== input_fh ===

This method takes a filehandle, processes it, tries to import DataObjs in to the repository and then returns a List of the DataObjs imported.

This array will be used to create a List of DataObjs later.
<pre>
        my @ids;
</pre>

Here we open the filehandle passed, and read the lines into an array.
<pre>
        my $fh = $opts{fh};
        my @records = <$fh>;
</pre>

We create a Text::CSV object to handle the input. Using a dedicated [http://en.wikipedia.org/wiki/Comma-Separated_Values CSV] handling package is preferable to using Perl's split function as it handles a number of more complicated scenarios such as commas within records using double quotes.
<pre>
        my $csv = Text::CSV->new();
</pre>

After setting up an array for metadata field names, we attempt to parse the first line of our file. The parse method does not return an array of fields, but reports success or failure. In the event of success we use the fields method to return the last fields parsed. In the event of failure we use the error_input method to get the last error, and return undef.
<pre>
        my @fields;
        if ($csv->parse(shift @records))
        {
                @fields = $csv->fields();
        }
        else
        {
                $plugin->error($csv->error_input);
                return undef;
        }
</pre>

Now that the row of column titles has been dealt with we move onto processing each record in the file.

In import plugins the convert_input method converts individual records into a format that can be imported into the repository. That is a hash whose keys are metadata field names and values are the corresponding values. As a row on its own cannot be imported as we don't know to which field each value belongs we have to construct an array to pass to convert_input first. We pass an array whose first element is the fields row and whose second element is the row we want to import.
<pre>
        foreach my $row (@records)
        {
                my @input_data = (join(',',@fields),$row);
</pre>

Here we call convert_input on our constructed input_data. If the conversion fails we simply move to the next record.
<pre>
                my $epdata = $plugin->convert_input(\@input_data);
                next unless defined $epdata;
</pre>

The epdata_to_dataobj method takes our epdata hash reference and turns it into a new DataObj in our repository. If it is successful it returns the new DataObj, whose id we add to our array of ids.
<pre>
                my $dataobj = $plugin->epdata_to_dataobj($opts{dataset},$epdata);
                if( defined $dataobj )
                {
                        push @ids, $dataobj->get_id;
                }
</pre>

Finally we return a List object containing the ids of the records we have successfully imported.
<pre>
        return EPrints::List->new(
                        dataset => $opts{dataset},
                        session => $plugin->{session},
                        ids=>\@ids );
</pre>