Modified the to_json filter again, according to Arjan Scherpenisse's …

…comment (zotonic#288 (comment))

modules/mod_base/filters/filter_to_json.erl

@@ -18,41 +18,46 @@
 
 %% Modified by François Cardinaux in order to convert UTF8 strings correctly
 %% Usage: 
-%%    * 8-bit character encoding (ASCII, ISO8859-x, etc.): 
+%%    * If the input value contains strings of UTF-8-encoded characters: 
 %%          {{ value|to_json }}
-%%    * UTF-8 character encoding: 
-%%          {{ value|to_json:"utf8" }}
-%%    * Unicode character encoding, as defined in the mochijson module: 
+%%    * If the input value contains strings of ASCII or ISO 8859-1 (= Latin-1) characters: 
+%%          {{ value|to_json:"latin-1" }}
+%%    * If the input value contains strings of unicode characters, as defined in the mochijson module: 
 %%          {{ value|to_json:"unicode" }}
+%% Note that these variants only concern the strings in the input term. 
+%% The output will always contain utf-8-encoded strings.  
 
 -module(filter_to_json).
 -export([to_json/2, to_json/3]).
 
-%% @doc Convert an Erlang list or tuple to JSON
+%% @doc Convert an Erlang list or tuple to JSON.
+%% This function assumes that the input contains only strings that are composed of utf-8 characters. 
+%% For other encodings, use to_json/3 instead.
 %% @spec to_json(ErlangTerm, Context) -> Json
 %% Where: 
 %%    * ErlangTerm = list() | tuple()
 %%    * Context = Zotonic context record
 %%    * Json = JSON content
 to_json(Value, _Context) ->
-    mochijson:encode(z_convert:to_json(Value)).
+    Encoder = mochijson:encoder([{input_encoding, utf8}]),
+    Encoder(z_convert:to_json(Value)).
 
 %% @doc Convert an Erlang list or tuple to JSON
 %% @spec to_json(ErlangTerm, Encoding, Context) -> Json
 %% Where: 
 %%    * ErlangTerm, Context and Json: like in to_json/2
-%%    * Encoding = 
-%%        * "utf8": ErlangTerm contains UTF8 strings
+%%    * Encoding: the character encoding of the strings in the input term (the output always contains utf-8 character strings)
+%%      The possible values are: 
+%%        * "latin-1": ErlangTerm contains strings of ISO 8859-1 characters (this character set encompasses ASCII characters)
 %%        * "unicode": ErlangTerm contains unicode strings, as defined in the mochijson module
-to_json(Value, "utf8", _Context) ->
-    Encoder = mochijson:encoder([{input_encoding, utf8}]),
-    Encoder(z_convert:to_json(Value));
+%%      For utf-8 input strings, use to_json/2 instead.
+to_json(Value, "latin-1", _Context) ->
+    mochijson:encode(z_convert:to_json(Value));
 
 to_json(Value, "unicode", _Context) ->
     Encoder = mochijson:encoder([{input_encoding, unicode}]),
     Encoder(z_convert:to_json(Value));
 
 to_json(Value, _Encoding, Context) ->
     to_json(Value, Context).
-