Added filter_datediff, contributed by Jason Tanner.

AUTHORS

@@ -18,6 +18,7 @@ Tim Benniks <tim@timbenniks.nl>
 # This can be code, templates or translations.
 
 Elise Lambert <lambert_elise@hotmail.com>
+Jason Tanner <jt4websites@googlemail.com>
 Kunthar <kunthar@gmail.com>
 Konstantin Nikiforov <helllamer@gmail.com>
 Michael Connors <michael@bring42.net>

modules/mod_base/filters/filter_datediff.erl

@@ -0,0 +1,54 @@
+%%----------------------------------------------------------------------------------------------------------------
+%% @author Jason Tanner <jt4websites@googlemail.com>
+%% @copyright 2010 Jason Tanner
+%% @doc 'datediff' filter, produce the difference between two dates selecting which date part is interesting.
+%%----------------------------------------------------------------------------------------------------------------
+
+%%----------------------------------------------------------------------------------------------------------------
+%% Copyright 2010 Jason Tanner
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%% 
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%% 
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%----------------------------------------------------------------------------------------------------------------
+
+-module(filter_datediff).
+-export([datediff/3]).
+
+datediff(undefined, _X, _Context) ->
+    undefined;
+datediff(_X, undefined, _Context) ->
+    undefined;
+datediff( {_Y,_M,_D} = Date, DatePart, Context) ->
+    datediff( [Date,{0,0,0}], DatePart, Context );
+datediff( {{_Y,_M,_D},{_H,_I,_S}} = DateTime, DatePart, Context) ->
+    datediff( [ DateTime, calendar:local_time() ], DatePart, Context );
+datediff( [ {{_Y,_M,_D},{_H,_I,_S}} = DateTimeA, {_YB,_MB,_DB} = DateB ], DatePart, Context) ->
+    datediff( [ DateTimeA, {DateB,{0,0,0}} ], DatePart, Context );
+datediff( [ {{_YA,_MA,_DA},{_HA,_IA,_SA}} = DateTimeA, {{_YB,_MB,_DB},{_HB,_IB,_SB}} = DateTimeB ], DatePart, _Context ) ->
+    {{Y,M,D},{H,I,S}} = z_datetime:diff( DateTimeA, DateTimeB ),
+    case DatePart of
+        "Y" -> Y;
+        "M" -> M;
+        "D" -> D;
+        "H" -> H;
+        "I" -> I;
+        "S" -> S;
+        _   -> Y    % Defaults to YEAR
+    end;
+datediff( [ DateStringA, DateStringB ], DatePart, Context ) when is_list(DateStringA), is_tuple(DateStringB) ->
+    datediff( [ z_convert:to_datetime(DateStringA), DateStringB ], DatePart, Context);
+datediff( [ DateStringA, DateStringB ], DatePart, Context ) when is_tuple(DateStringA), is_list(DateStringB) ->
+    datediff( [ DateStringA, z_convert:to_datetime(DateStringB) ], DatePart, Context);
+datediff( [ DateStringA, DateStringB ], DatePart, Context ) when is_list(DateStringA), is_list(DateStringB) ->
+    datediff( [ z_convert:to_datetime(DateStringA), z_convert:to_datetime(DateStringB) ], DatePart, Context);
+datediff( DateString, DatePart, Context ) when is_list(DateString) ->
+    datediff(z_convert:to_datetime(DateString), DatePart, Context).