def _mapreduce_keyfilter(self, index, keyfilter, sortby=None, limit=None):
"""
Helper function to execute a map-reduce query using the given key filter
"""
results = None
log.debug("Riak query %r with key filter %r", index, keyfilter)
mapred = RiakMapReduce(self.client)
mapred.add_bucket(self._get_bucket(index))
mapred.add_key_filters(keyfilter)
# custom Riak.mapValuesJson() function that also adds the entry key to the data structure
mapred.map("""
function(value, keyData, arg) {
if (value.not_found) {
return [value];
}
var _data, data = value["values"][0]["data"];
if (Riak.getClassName(data) !== "Array") {
_data = JSON.parse(data);
_data["_key"] = value.key;
return [_data];
}
else {
return data
}
}
""")
if sortby is not None:
comp = '<' if limit is not None and limit < 0 else '>'
mapred.reduce_sort('function(a,b){ return (a.%s || 0) %s (b.%s || 0) ? 1 : 0; }' % (sortby, comp, sortby))
if limit is not None:
mapred.reduce_limit(abs(limit))
try:
results = mapred.run()
except Exception, e:
log.warning("Riak MapReduce exception: %s", str(e))
results = None
