./ct_report/coverage/mongoose_graphql_sse_handler.COVER.html

1 %% @doc An SSE handler for GraphQL subscriptions.
2 %% The graphql request is prepared, and then executed.
3 %%
4 %% 1. The first execution should return 'null' in 'data', and a new Stream in 'aux'.
5 %% 2. Then, whenever an Event is received, the prepared GraphQL request
6 %% is executed again, this time with the Stream and the Event in the context.
7 %% The resolver should then return either 'null' or the processed Event to send to the client.
8 %% 3. Upon termination, the request is executed one last time with the 'terminate' event.
9 %% This is an opportunity to clean up all stream resources.
10 -module(mongoose_graphql_sse_handler).
11
12 -behaviour(lasse_handler).
13 -export([init/3,
14 handle_notify/2,
15 handle_info/2,
16 handle_error/3,
17 terminate/3]).
18
19 -include("mongoose.hrl").
20
21 -type req() :: cowboy_req:req().
22 -type state() :: #{atom() => term()}.
23
24 -spec init(state(), any(), cowboy_req:req()) ->
25 {ok, req(), state()} |
26 {shutdown, cowboy:http_status(), cowboy:http_headers(), iodata(), req(), state()}.
27 init(State, _LastEvtId, Req) ->
28 15 process_flag(trap_exit, true), % needed for 'terminate' to be called
29 15 case cowboy_req:method(Req) of
30 <<"GET">> ->
31 13 case mongoose_graphql_handler:check_auth_header(Req, State) of
32 {ok, State2} ->
33 11 case mongoose_graphql_handler:gather(Req) of
34 {ok, Req2, Decoded} ->
35 9 run_request(Decoded, Req2, State2);
36 {error, Reason} ->
37 2 reply_error(Reason, Req, State)
38 end;
39 {error, Reason} ->
40 2 reply_error(Reason, Req, State)
41 end;
42 _ ->
43 2 {ok, Req, State} % lasse returns 405: Method Not Allowed
44 end.
45
46 run_request(#{document := undefined}, Req, State) ->
47 2 reply_error(make_error(decode, no_query_supplied), Req, State);
48 run_request(GQLReq, Req, #{schema_endpoint := EpName, authorized := AuthStatus} = State) ->
49 7 Ep = mongoose_graphql:get_endpoint(EpName),
50 7 Ctx = maps:get(schema_ctx, State, #{}),
51 7 GQLReq2 = GQLReq#{authorized => AuthStatus, ctx => Ctx#{method => sse}},
52 7 case mongoose_graphql:prepare(Ep, GQLReq2) of
53 {error, Reason} ->
54 4 reply_error(Reason, Req, State);
55 {ok, GQLReq3 = #{ctx := Ctx2}} ->
56 3 case mongoose_graphql:execute(Ep, GQLReq3) of
57 {ok, #{aux := [{stream, Stream}]}} ->
58 2 Ctx3 = Ctx2#{stream => Stream},
59 2 {ok, Req, State#{id => 1, ep => Ep, req => GQLReq3#{ctx := Ctx3}}};
60 {ok, Response} ->
61 1 Body = mongoose_graphql_response:term_to_json(Response),
62 1 {shutdown, 200, #{}, Body, Req, State}
63 end
64 end.
65
66 -spec handle_notify(term(), state()) -> {nosend, state()}.
67 handle_notify(Msg, State) ->
68 
:-(
 ?UNEXPECTED_INFO(Msg),
69 
:-(
 {nosend, State}.
70
71 -spec handle_info(term(), state()) -> {nosend, state()} | {send, lasse_handler:event(), state()}.
72 handle_info(Event, State = #{ep := Ep, req := Req = #{ctx := Ctx}, id := Id}) ->
73 3 Ctx1 = Ctx#{event => Event},
74 3 {ok, #{data := Data} = Response} = mongoose_graphql:execute(Ep, Req#{ctx := Ctx1}),
75 3 case has_non_null_value(Data) of
76 false ->
77 1 {nosend, State};
78 true ->
79 2 EventData = mongoose_graphql_response:term_to_json(Response),
80 2 SseEvent = #{id => integer_to_binary(Id), data => EventData},
81 2 {send, SseEvent, State#{id := Id + 1}}
82 end.
83
84 %% Check if there is any value that is non-null. Any list is considered non-null.
85 has_non_null_value(M) when is_map(M) ->
86 8 lists:any(fun has_non_null_value/1, maps:values(M));
87 3 has_non_null_value(V) -> V =/= null.
88
89 -spec handle_error(iodata(), term(), state()) -> ok.
90 handle_error(Msg, Reason, _State) ->
91 
:-(
 ?LOG_ERROR(#{what => mongoose_graphql_sse_handler_failed,
92 
:-(
 reason => Reason, text => Msg}).
93
94 -spec terminate(term(), req(), state()) -> ok.
95 terminate(_Reason, _Req, #{ep := Ep, req := Req = #{ctx := Ctx}}) ->
96 2 Ctx1 = Ctx#{event => terminate},
97 2 {ok, #{aux := [{stream, closed}]}} = mongoose_graphql:execute(Ep, Req#{ctx := Ctx1}),
98 2 ok;
99 terminate(_Reason, _Req, #{}) ->
100 11 ok.
101
102 make_error(Phase, Term) ->
103 2 #{error_term => Term, phase => Phase}.
104
105 reply_error(Reason, Req, State) ->
106 10 {Code, Error} = mongoose_graphql_errors:format_error(Reason),
107 10 Body = jiffy:encode(#{errors => [Error]}),
108 10 {shutdown, Code, #{}, Body, Req, State}.
Line Hits Source