erlangriakcrdt

Syntax for setting/updating register fields in Map CRDT on server

What is the syntax for setting lwwreg register values in CRDT Map on server side in Riak? I tried a code like below which doesn't seem to be valid:

%% Obj is a map object to which we want to add/set a register "uname" with value
%% "ahmed"
riak_kv_crdt:update(Obj,<<"testing">>,{crdt_op,riak_dt_map,
{update,[{assign,<<"uname">>,<<"ahmed">>}]},undefined})

I get an error about the operation being invalid - I looked around in source code for riak_dt_map.erl but still can't figure out correct syntax:

> riak_kv_crdt:update(Obj,<<"testing">>,{crdt_op,riak_dt_map,{update,
  [{assign,<<"uname">>,<<"ahmed">>}]},undefined}).

** exception error: no function clause matching 
                    riak_dt_map:apply_ops([{assign,<<"uname">>,<<"ahmed">>}],
                                          {<<"testing">>,1},
                                          {[{<<"testing">>,1}],
                    .....

Will appreciate pointers on correct syntax.

Solution

  • Figured it out. The correct syntax is below - the key must be accompanied by the type of the field which is riak_dt_lwwreg in this case, and assign operation must be specified for register value - so, the syntax becomes:

    riak_kv_crdt:update(Obj,<<"testing">>,{crdt_op,riak_dt_map,{update,
[{update,{<<"uname">>,riak_dt_lwwreg},{assign,<<"ahmed">>}}]},undefined})