fieldmask implements Partial Responses protocol of Google+ API in Erlang, like json-mask in JavaScript and jsonmask in Python.
Mask of fieldmask is the same as fields parameter of Google+ API, for example, <<"a,b">> means the fields you want to keep is "a" and "b".
1> Mask = <<"a,b">>.
<<"a,b">>
And fieldmask use map object format of jsone to represent a JSON value.
2> Value = jsone:decode(<<"{\"a\":1, \"b\": 2, \"c\": 3}">>).
#{<<"a">> => 1,<<"b">> => 2,<<"c">> => 3}.
Call fieldmask:mask/2 to get the specific parts of a value you've selected.
3> fieldmask:mask(Mask, Value).
#{<<"a">> => 1,<<"b">> => 2}
add fieldmask dependency to your project's rebar.config
{deps, [fieldmask]}.
fieldmask is released under Apache 2 License. Check LICENSE file for more information.