Merge pull request #8 from talko/fixes/query

Expose additional APIs

src/ddb.erl

@@ -27,11 +27,14 @@
          key_type/2, key_type/4,
          key_value/2, key_value/4,
          create_table/4, describe_table/1, remove_table/1,
-         get/2, put/2, update/3, update/4, 
+         get/2, get/3, put/2, update/3, update/4, 
          delete/2, delete/3, 
+	 cond_put/3,
          cond_update/4, cond_update/5,
          cond_delete/3, cond_delete/4,
-         now/0, find/3, find/4]).
+         now/0, find/3, find/4,
+	 q/3, q/4,
+	 range_key_condition/1]).
 
 -define(DDB_DOMAIN, "dynamodb.us-east-1.amazonaws.com").
 -define(DDB_ENDPOINT, "http://" ++ ?DDB_DOMAIN ++ "/").
@@ -79,6 +82,8 @@
 -type update_attr() :: {binary(), binary(), type(), 'put' | 'add'} | {binary(), 'delete'}.
 -type returns() :: 'none' | 'all_old' | 'updated_old' | 'all_new' | 'updated_new'.
 -type update_cond() :: {'does_not_exist', binary()} | {'exists', binary(), binary(), type()}.
+-type json_parameter() :: {binary(), term()}.
+-type json_parameters() :: [json_parameter()].
 
 %%% Set temporary credentials, use ddb_iam:token/1 to fetch from AWS.
 
@@ -176,6 +181,18 @@ put(Name, Attributes)
             {<<"Item">>, format_put_attrs(Attributes)}],
     request(?TG_PUT_ITEM, JSON).
 
+%%% Conditionally put item attributes into table
+
+-spec cond_put(tablename(), [put_attr()], update_cond()) -> json_reply().
+
+cond_put(Name, Attributes, Condition)
+  when is_binary(Name),
+       is_list(Attributes) ->
+    JSON = [{<<"TableName">>, Name},
+            {<<"Item">>, format_put_attrs(Attributes)}]
+	++ format_update_cond(Condition),
+    request(?TG_PUT_ITEM, JSON).
+
 %%% Create a key value, either hash or hash and range.
 
 -spec key_value(binary(), type()) -> json().
@@ -286,6 +303,18 @@ get(Name, Keys)
     JSON = [{<<"TableName">>, Name}] ++ Keys,
     request(?TG_GET_ITEM, JSON).
 
+%%% get with additional parameters
+
+-spec get(tablename(), key_json(), json_parameters()) -> json_reply().
+
+get(Name, Keys, Parameters)
+  when is_binary(Name),
+       is_list(Keys) ->
+    JSON = [{<<"TableName">>, Name}] 
+	++ Keys
+	++ Parameters,
+    request(?TG_GET_ITEM, JSON).
+
 %%% Fetch all item attributes from table using a condition.
 
 -spec find(tablename(), key_value(), find_cond()) -> json_reply().
@@ -297,11 +326,23 @@ find(Name, HashKey, RangeKeyCond) ->
 
 -spec find(tablename(), key_value(), find_cond(), json() | 'none') -> json_reply().
 
-find(Name, {HashKeyValue, HashKeyType}, {Condition, RangeKeyType, RangeKeyValues}, StartKey)
+find(Name, {HashKeyValue, HashKeyType}, RangeKeyCond, StartKey)
   when is_binary(Name),
        is_binary(HashKeyValue),
-       is_atom(HashKeyType),
-       is_atom(Condition),
+       is_atom(HashKeyType) ->
+    JSON = [{<<"TableName">>, Name},
+            {<<"HashKeyValue">>, 
+             [{type(HashKeyType), HashKeyValue}]},
+	    range_key_condition(RangeKeyCond)]
+	++ start_key(StartKey),
+
+    request(?TG_QUERY, JSON).
+
+%%% Create a range key condition parameter
+
+-spec range_key_condition(find_cond()) -> json_parameter().
+range_key_condition({Condition, RangeKeyType, RangeKeyValues})
+  when is_atom(Condition),
        is_atom(RangeKeyType),
        is_list(RangeKeyValues) ->
     {Op, Values} = case Condition of
@@ -312,22 +353,41 @@ find(Name, {HashKeyValue, HashKeyType}, {Condition, RangeKeyType, RangeKeyValues
                        'equal' ->
                            {<<"EQ">>, [[{type(RangeKeyType), hd(RangeKeyValues)}]]}
                    end,
+    {<<"RangeKeyCondition">>, [{<<"AttributeValueList">>, Values},
+			       {<<"ComparisonOperator">>, Op}]}.
+
+%%% Query a table
+
+-spec q(tablename(), key_value(), json_parameters()) -> json_reply().
+
+q(Name, HashKey, Parameters) ->
+    q(Name, HashKey, Parameters, 'none').
+
+%% Query a table with pagination
+
+-spec q(tablename(), key_value(), json_parameters(), json() | 'none') -> json_reply().
+
+q(Name, {HashKeyValue, HashKeyType}, Parameters, StartKey)
+  when is_binary(Name),
+       is_binary(HashKeyValue),
+       is_atom(HashKeyType),
+       is_list(Parameters) ->
     JSON = [{<<"TableName">>, Name},
-            {<<"HashKeyValue">>, 
-             [{type(HashKeyType), HashKeyValue}]},
-            {<<"RangeKeyCondition">>, 
-             [{<<"AttributeValueList">>, Values},
-              {<<"ComparisonOperator">>, Op}]}],
-    JSON1 = case StartKey of 
-                'none' -> JSON;
-                _      -> [{<<"ExclusiveStartKey">>, StartKey}|JSON]
-            end,
-    request(?TG_QUERY, JSON1).
+            {<<"HashKeyValue">>, [{type(HashKeyType), HashKeyValue}]}]
+	++ Parameters
+	++ start_key(StartKey),
+    request(?TG_QUERY, JSON).
 
 %%%
 %%% Helper functions
 %%%
 
+-spec start_key(json() | 'none') -> json_parameters().
+start_key('none') -> 
+    [];
+start_key(StartKey) -> 
+    [{<<"ExclusiveStartKey">>, StartKey}].
+
 -spec format_put_attrs([put_attr()]) -> json().
 
 format_put_attrs(Attributes) ->
@@ -378,6 +438,7 @@ update_action('delete') -> <<"DELETE">>.
 
 request(Target, JSON) ->
     Body = jsx:term_to_json(JSON),
+    ok = lager:debug("REQUEST BODY ~n~p", [Body]),
     Headers = headers(Target, Body),
     Opts = [{'response_format', 'binary'}],
     F = fun() -> ibrowse:send_req(?DDB_ENDPOINT, [{'Content-type', ?CONTENT_TYPE} | Headers], 'post', Body, Opts) end,