Toaster at 17:44, 16 September 2008

2008-09-16T17:44:04Z

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==Querying MCAT for one item==

This will query the MCAT for one item
* queryItem is the SRBMetaDataSet item to query against
* test is the MetaDataCondition test to use
* selectItem is the desired return item

It will return a list of results. See below for examples on using this to list files in a directory.

<pre>
public static List<String> queryForOneItem( SRBFileSystem sfs,
String queryItem, int test, String query, String selectItem ) throws IOException
{
if ( sfs == null )
throw new NullPointerException("SRBFile is null");

/**
* Construct query
*/
MetaDataCondition[] conditions = { MetaDataSet.newCondition(
queryItem, test, query )
};

String[] selectStrings =
{
selectItem
};

MetaDataSelect[] selects = MetaDataSet.newSelection(selectStrings);
MetaDataRecordList[] rl = sfs.query( conditions, selects, 300 );
ArrayList<String> results = new ArrayList<String>();

while (rl != null && rl.length > 0)
{

for (MetaDataRecordList r : rl)
{

results.add(r.getValue(selectItem).toString());
}

if (!rl[rl.length-1].isQueryComplete())
{
rl = rl[rl.length-1].getMoreResults();
}
else
{
rl = null;
}
}
return results;
}
</pre>

==Listing Files and directories==

Here's a shortcut to listing files and directories w/o using srb file, using the metadata hack above

<pre>
public static List<String> listFilesInDirectory( SRBFileSystem sfs, String directory ) throws IOException
{
if ( sfs == null || StringUtil.isEmpty(directory))
throw new NullPointerException("SRBFile or directory is null or empty");

String path = (directory.endsWith("/")
? directory.substring(0,directory.length() - 1)
: directory);

return queryForOneItem(sfs, SRBMetaDataSet.DIRECTORY_NAME,
MetaDataCondition.EQUAL, path, SRBMetaDataSet.FILE_NAME);
}

public static List<String> listDirectoriesInDirectory( SRBFileSystem sfs, String directory ) throws IOException
{
if ( sfs == null || StringUtil.isEmpty(directory))
throw new NullPointerException("SRBFile or directory is null or empty");

String path = (directory.endsWith("/")
? directory.substring(0,directory.length() - 1)
: directory);

return queryForOneItem(sfs, SRBMetaDataSet.PARENT_DIRECTORY_NAME,
MetaDataCondition.EQUAL, path, SRBMetaDataSet.DIRECTORY_NAME);
}

</pre>

-- Main.MikeSmorul - 07 Dec 2006

SRB:Jargon Tips - Revision history

Toaster at 17:44, 16 September 2008