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<p class="MsoNormal">Hi All,<o:p></o:p></p>
<p class="MsoNormal">Can anyone validate this for me?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On this page: <a href="https://wiki.eprints.org/w/API:EPrints/Search#add_field">
https://wiki.eprints.org/w/API:EPrints/Search#add_field</a> (generated from perldoc in EPrints::Search), the following statement is made for the value:<o:p></o:p></p>
<p class="MsoNormal">"value - value to match against (for EX matches, NULL = is_null!)"<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This has always seemed very cryptic/unhelpful to me - but I've never needed to get a null search working - until now.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Experimentation has led to the following which seems to work (example: searching buffer for items with no date):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">my $ds = $session->dataset( "buffer" );<o:p></o:p></p>
<p class="MsoNormal">my $searchexp = $ds->prepare_search();<o:p></o:p></p>
<p class="MsoNormal">$searchexp->add_field(<o:p></o:p></p>
<p class="MsoNormal"> fields => [<o:p></o:p></p>
<p class="MsoNormal"> $ds->field( 'date' ),<o:p></o:p></p>
<p class="MsoNormal"> ],<o:p></o:p></p>
<p class="MsoNormal"> value => undef,<o:p></o:p></p>
<p class="MsoNormal"> match => "EX",<o:p></o:p></p>
<p class="MsoNormal">);<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-the 'value => undef,' being the critical piece.<o:p></o:p></p>
<p class="MsoNormal">Before I add this to the Wiki, can anyone else confirm this is correct?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers,<o:p></o:p></p>
<p class="MsoNormal">John<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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