Riak Solr Client

riak_solr_client.erl

-module(riak_solr_client).
-author("Ivan Blinkov <ivan@blinkov.ru>").

%% WARNING: Not yet tested in production, use with care.
%%
%% This module provides access to sort and limit/offset features of Riak 
%% accessible only via Solr interface.
%%
%% Supposed to be used with conjunction with: 
%% https://github.com/basho/riak-erlang-client
%%
%% Dependencies:
%% - https://github.com/davisp/jiffy
%% - https://github.com/esl/lhttpc

-export(search/4, search/5).

-type bucket() :: binary().
-type key() :: binary() | 'undefined'.
-type vclock() :: binary().
-type metadata() :: dict().
-type content_type() :: string().
-type value() :: binary().
-type contents() :: [{metadata(), value()}].

-record(riakc_obj, {
          bucket :: bucket(),
          key :: key(),
          vclock :: vclock(),
          contents :: contents(),
          updatemetadata :: dict(),
          updatevalue :: value()
         }).

-define(RIAK_HOST, "127.0.0.1").
-define(SOLR_PORT, 8098).

-spec search(Bucket :: string(), SearchQuery :: string(),
	Sort :: string(), Page :: integer()) -> [#riakc_obj{}].
search(Bucket, SearchQuery, Sort, Page) ->
	search(Bucket, SearchQuery, Sort, Page, 10).

-spec search(Bucket :: string(), SearchQuery :: string(),
	Sort :: string(), Page :: integer(), PageSize :: integer()) -> [#riakc_obj{}].
search(Bucket, SearchQuery, Sort, Page, PageSize) ->
	Start = (Page - 1) * PageSize,
	Path = "/solr/" ++ Bucket ++ "/select?wt=json&start=" 
		++ integer_to_list(Start) ++ "&rows=" ++ integer_to_list(PageSize) 
		++ "&sort=" ++ Sort ++ "&q=" ++ re:replace(SearchQuery, "\s", "%20", [global, {return, list}]),
	case lhttpc:request(?RIAK_HOST, ?SOLR_PORT, 
		false, Path, 'GET', [], <<>>, 30000, []) of
	{ok, {{200,"OK"}, _Headers, QueryResponse}} ->
		{[{<<"responseHeader">>,_}, {<<"response">>, Response}]} = jiffy:decode(QueryResponse),
		{[_, _, _, {<<"docs">>, Docs}]} = Response,
		lists:map(fun wrap_search_results/1, Docs);
	[] ->
		[]
	end.

-spec field_to_propvalue(Tuple :: tuple()) -> [#riakc_obj{}].
wrap_search_results(Tuple) ->
	{[{<<"id">>, Key},
   		{<<"index">>, Bucket},
   		{<<"fields">>, {Fields}},
   		{<<"props">>,_}]} = Tuple,
        #riakc_obj{bucket = Bucket, key = Key, contents = [], 
                updatevalue = lists:map(fun field_to_propvalue/1, Fields)}.


-spec field_to_propvalue(Field :: tuple()) -> tuple().
field_to_propvalue(Field) ->
	{Key, Value} = Field,
	{list_to_atom(binary_to_list(Key)), Value}.