Hi,
I have written some code to query a view within Erlang and it seems
too simple :-) Am I really just looping through a view and returning
{ok, State} if a key matches a particular input KeyId and calling
{stop, State} when I want the iteration to stop?
I appreciate there is an index behind the view which makes things
fast, but the looping seems really simple. Verification of this
approach would be very much appreciated as I go forward!
case couch_view:get_map_view(Db, DesignId, ViewName, []) of
{ok, View, Group} ->
FoldlFun = fun({{Key, DocId}, Value}, _, {MaxRecords,
StartPos, Counter, DocIdList}=Acc) ->
case Key == KeyId of
true ->
case Counter < StartPos of
true ->
% not emitting a value yet until we go past StartPos
{ok, {MaxRecords, StartPos, Counter + 1,
DocIdList}};
_ ->
case (Counter - StartPos) < MaxRecords of
true ->
{ok, {MaxRecords, StartPos, Counter +
1, [DocId] ++ DocIdList}};
_ ->
% gone past max records
{stop, Acc}
end
end;
_ ->
{stop, Acc}
end
end,
FoldAccInit = {MaxRecords, StartPos, 0, []},
case couch_view:fold(View, {KeyId, nil}, fwd, FoldlFun,
FoldAccInit) of
{ok, {_, _, _, DocIdList}} ->
io:fwrite("LIST ~p ViewName ~p ~n", [DocIdList, ViewName]);
_ ->
throw({error, {[{code, "NoApplicableCode"},
{reason, "Error parsing view" ++ binary_to_list(ViewName)}]}})
end;
{not_found, Reason} ->
throw({error, {[{code, "NoApplicableCode"}, {reason, Reason}]}})
end;
thanks,
Norman
