Interaction with a Riak node in which maps with nested fields are used.

riakc_interaction.erl

%% Start connection to riak node
{ok, Pid} = riakc_pb_socket:start_link("127.0.0.1",8087).

%% Create new local riak map object.
Map = riakc_map:new().

%% Perform a local update taking the previous map and inserting a nested set inside.
Map1 = riakc_map:update({<<"set">>, set},
  %% update a nested key called <<"set">> of type set
  %% pass it an update function that adds X and Y to it.
    fun(S) -> riakc_set:add_element(<<"X">>,riakc_set:add_element(<<"Y">>, S)) end,
  Map).

%% Save map to Riak
ok = riakc_pb_socket:update_type(
  %% structure of update_type
  %% (Pid, {bucket_type, bucket_name}, key, object)
  Pid, {<<"maps">>, <<"bucket">>}, <<"key">>, riakc_map:to_op(Map1)
).

%% Fetch map from riak.
{ok, M0} = riakc_pb_socket:fetch_type(Pid, {<<"maps">>, <<"bucket">>}, <<"key">>).

%% Fetch nested set.
L0 = riakc_map:fetch({<<"set">>, set}, M0).

%% check that what we got from riak contains exactly what we added before.
true = lists:member(<<"X">>, L0).
true = lists:member(<<"Y">>, L0).
2 = length(L0).

%% further mutate the map (locally) by deleting X and adding Z to the set.
M1 = riakc_map:update({<<"set">>, set},
    fun(S) -> riakc_set:del_element(<<"X">>, riakc_set:add_element(<<"Z">>, S)) end,
  M0).

%% send the current version to Riak.
ok = riakc_pb_socket:update_type(
    Pid, {<<"maps">>, <<"bucket">>}, <<"key">>, riakc_map:to_op(M1)
  ).

%% fetch map from Riak again to check for changes
{ok, M2} = riakc_pb_socket:fetch_type(Pid, {<<"maps">>, <<"bucket">>}, <<"key">>).

%% fetch nested set from map
L1 = riakc_map:fetch({<<"set">>, set}, M2).

%% check that what we got from riak contains exactly what we added before.
true = lists:member(<<"Y">>, L1).
true = lists:member(<<"Z">>, L1).
2= length(L1).