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@ArthurClemens ArthurClemens/m_omdb.erl
Last active Aug 3, 2016

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Zotonic template model for the OMDB movie database - source code to accompany the documentation
-module(m_omdb).
-behaviour(gen_model).
-export([
m_find_value/3,
m_to_list/2,
m_value/2
]).
-include_lib("zotonic.hrl").
-define(API_URL, "http://www.omdbapi.com/?").
-spec m_find_value(Key, Source, Context) -> #m{} | undefined | any() when
Key:: integer() | atom() | string(),
Source:: #m{},
Context:: #context{}.
% Syntax: m.omdb.api_url
m_find_value(api_url, _, _Context) ->
?API_URL;
% Syntax: m.omdb.movie[QueryString]
m_find_value(movie, #m{value=undefined} = M, _Context) ->
M#m{value=[{type, "movie"}]};
% Syntax: m.omdb.series[QueryString]
m_find_value(series, #m{value=undefined} = M, _Context) ->
M#m{value=[{type, "series"}]};
% Syntax: m.omdb.episode[QueryString]
m_find_value(episode, #m{value=undefined} = M, _Context) ->
M#m{value=[{type, "episode"}]};
% Syntax: m.omdb["tt0123456789"]
m_find_value("tt" ++ _Number = Id, #m{value=undefined} = M, _Context) ->
M#m{value=[{id, Id}]};
% Syntax: m.omdb.sometype["tt0123456789"]
m_find_value("tt" ++ _Number = Id, #m{value=Query} = M, _Context) when is_list(Query) ->
M#m{value=[{id, Id}] ++ Query};
% Syntax: m.omdb["some title"]
m_find_value(Title, #m{value=undefined} = M, _Context) when is_list(Title) ->
M#m{value=[{title, Title}]};
% Syntax: m.omdb.sometype["some title"]
% If no atom is passed it must be a title (string)
m_find_value(Title, #m{value=Query} = M, _Context) when is_list(Title) ->
M#m{value=[{title, Title}] ++ Query};
% Syntax: m.omdb[{query QueryParams}]
% For m.omdb[{query title="Dollhouse"}], Query is: [{title,"Dollhouse"}]
m_find_value({query, Query}, #m{value=undefined} = M, _Context) ->
M#m{value=Query};
% Syntax: m.omdb.sometype[{query QueryParams}]
% For m.omdb.series[{query title="Dollhouse"}], Query is: [{title,"Dollhouse"}] and Q is: [{type,"series"}]
m_find_value({query, Query}, #m{value=Q} = M, _Context) when is_list(Q) ->
M#m{value=Query ++ Q};
% Syntax: m.omdb[QueryString].title or m.omdb.sometype[QueryString].title
% Key is in this case 'title'
m_find_value(Key, #m{value=Query} = _M, _Context) when is_atom(Key) ->
proplists:get_value(Key, fetch_data(Query));
% Other values won't be processed
m_find_value(_, _, _Context) ->
undefined.
-spec m_to_list(Source, Context) -> list() when
Source:: #m{},
Context:: #context{}.
m_to_list(#m{value=undefined} = _M, _Context) ->
[];
m_to_list(#m{value=Query} = _M, _Context) ->
fetch_data(Query).
-spec m_value(Source, Context) -> undefined | any() when
Source:: #m{},
Context:: #context{}.
m_value(_, _Context) ->
undefined.
-spec fetch_data(Query) -> list() when
Query:: list().
fetch_data([]) ->
[{error, "Params missing"}];
fetch_data(Query) ->
case proplists:is_defined(title, Query) or proplists:is_defined(id, Query) of
false -> [{error, "Param id or title missing"}];
true ->
QueryParts = lists:map(fun(Q) ->
make_query_string(Q)
end, Query),
Url = ?API_URL ++ string:join(QueryParts, "&"),
case get_page_body(Url) of
{error, Error} ->
[{error, Error}];
Json ->
{struct, JsonData} = mochijson2:decode(Json),
lists:map(fun(D) ->
convert_data_prop(D)
end, JsonData)
end
end.
%% Translate query params id, title and type into parameters that OMDB wants
-spec make_query_string({Key, Value}) -> string() when
Key:: atom(),
Value:: string().
make_query_string({id, Id}) ->
"i=" ++ Id;
make_query_string({title, Title}) ->
"t=" ++ re:replace(Title, " ", "+", [global, {return, list}]);
make_query_string({type, Type}) ->
"type=" ++ Type;
make_query_string(_) ->
"".
%% Translate binary keys to atoms
-spec convert_data_prop({Key, Value}) -> {atom(), string()} when
Key:: binary(),
Value:: binary().
convert_data_prop({Key, Value}) ->
{z_convert:to_atom(string:to_lower(z_convert:to_list(Key))), Value}.
get_page_body(Url) ->
case httpc:request(get, {Url, []}, [], []) of
{ok, {_, Headers, Body}} ->
case content_length(Headers) of
0 -> {error, "No content"};
_ -> Body
end;
Error ->
{error, Error}
end.
content_length(Headers) ->
list_to_integer(proplists:get_value("content-length", Headers, "0")).
@tahteche

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tahteche commented Aug 3, 2016

For a query like m.omdb[{query QueryParams}] or m.omdb.movie[QueryString] is m_to_list/2 automatically called after looping through m_find_value/3?
I am asking because in those cases you do not call fetch_data/1 from within m_find_value/3 like you do in the case where the query is m.omdb[QueryString].title

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