Create sumo_single_entity_handler #4
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,121 @@ | ||
| %%% @doc Base GET|PUT|DELETE /[entity]s/:id implementation | ||
| -module(sr_single_entity_handler). | ||
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| -include_lib("mixer/include/mixer.hrl"). | ||
| -mixin([{ sr_entities_handler | ||
| , [ init/3 | ||
| , allowed_methods/2 | ||
| , content_types_provided/2 | ||
| , announce_req/2 | ||
| , handle_exception/3 | ||
| ] | ||
| }]). | ||
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| -export([ rest_init/2 | ||
| , resource_exists/2 | ||
| , content_types_accepted/2 | ||
| , handle_get/2 | ||
| , handle_put/2 | ||
| , delete_resource/2 | ||
| ]). | ||
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| -type options() :: #{ path => string() | ||
| , model => module() | ||
| , verbose => boolean() | ||
| }. | ||
| -type state() :: #{ opts => options() | ||
| , id => binary() | ||
| , entity => sumo:user_doc() | ||
| }. | ||
| -export_type([state/0, options/0]). | ||
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| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | ||
| %%% Cowboy Callbacks | ||
| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | ||
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| -spec rest_init(cowboy_req:req(), options()) -> | ||
| {ok, cowboy_req:req(), state()}. | ||
| rest_init(Req, Opts) -> | ||
| Req1 = announce_req(Req, Opts), | ||
| {Id, Req2} = cowboy_req:binding(id, Req1), | ||
| {ok, Req2, #{opts => Opts, id => Id}}. | ||
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| -spec resource_exists(cowboy_req:req(), state()) -> | ||
| {boolean(), cowboy_req:req(), state()}. | ||
| resource_exists(Req, State) -> | ||
| #{opts := #{model := Model}, id := Id} = State, | ||
| case sumo:find(Model, Id) of | ||
| notfound -> {false, Req, State}; | ||
| Entity -> {true, Req, State#{entity => Entity}} | ||
| end. | ||
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| %% @todo Use swagger's 'consumes' to auto-generate this if possible | ||
| %% @see https://github.com/inaka/sumo_rest/issues/7 | ||
| -spec content_types_accepted(cowboy_req:req(), state()) -> | ||
| {[{{binary(), binary(), '*'}, atom()}], cowboy_req:req(), state()}. | ||
| content_types_accepted(Req, State) -> | ||
| {[{{<<"application">>, <<"json">>, '*'}, handle_put}], Req, State}. | ||
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| -spec handle_get(cowboy_req:req(), state()) -> | ||
| {iodata(), cowboy_req:req(), state()}. | ||
| handle_get(Req, State) -> | ||
| #{opts := #{model := Model}, entity := Entity} = State, | ||
| ResBody = sr_json:encode(Model:to_json(Entity)), | ||
| {ResBody, Req, State}. | ||
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| -spec handle_put(cowboy_req:req(), state()) -> | ||
| {{true, binary()} | false | halt, cowboy_req:req(), state()}. | ||
| handle_put(Req, #{entity := Entity} = State) -> | ||
| #{opts := #{model := Model}} = State, | ||
| try | ||
| {ok, Body, Req1} = cowboy_req:body(Req), | ||
| Json = sr_json:decode(Body), | ||
| handle_put(Model:update(Entity, Json), Req1, State) | ||
| catch | ||
| _:badjson -> | ||
| Req3 = cowboy_req:set_resp_body(<<"Malformed JSON request">>, Req), | ||
| {false, Req3, State}; | ||
| _:Exception -> handle_exception(Exception, Req, State) | ||
| end; | ||
| handle_put(Req, #{id := Id} = State) -> | ||
| #{opts := #{model := Model}} = State, | ||
| try | ||
| {ok, Body, Req1} = cowboy_req:body(Req), | ||
| Json = sr_json:decode(Body), | ||
| handle_put(from_json(Model, Id, Json), Req1, State) | ||
| catch | ||
| _:badjson -> | ||
| Req3 = cowboy_req:set_resp_body(<<"Malformed JSON request">>, Req), | ||
| {false, Req3, State}; | ||
| _:Exception -> handle_exception(Exception, Req, State) | ||
| end. | ||
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| -spec delete_resource(cowboy_req:req(), state()) -> | ||
| {boolean() | halt, cowboy_req:req(), state()}. | ||
| delete_resource(Req, State) -> | ||
| #{opts := #{model := Model}, id := Id} = State, | ||
| try | ||
| Result = sumo:delete(Model, Id), | ||
| {Result, Req, State} | ||
| catch | ||
| _:Exception -> handle_exception(Exception, Req, State) | ||
| end. | ||
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| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | ||
| %%% Auxiliary Functions | ||
| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% | ||
| from_json(Model, Id, Json) -> | ||
| case erlang:function_exported(Model, from_json, 2) of | ||
|
There was a problem hiding this comment. The "problem" with incredibly useful and generic code that does things automagically is that it is often hard to debug when things go wrong. E.g. if the user programmer fails to export the proper functions, all they will get is a stacktrace. If exporting a certain function is a requirement and a source of a possibly foreseeable error, should it not be handled? There was a problem hiding this comment. Specifically, should it not check it from_json/1 is exported and if not, emit a readable error? There was a problem hiding this comment. It's checked at compile time, since it's a callback in the |
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| true -> Model:from_json(Id, Json); | ||
| false -> Model:from_json(Json) | ||
| end. | ||
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| handle_put({error, Reason}, Req, State) -> | ||
| Req1 = cowboy_req:set_resp_body(Reason, Req), | ||
| {false, Req1, State}; | ||
| handle_put({ok, Entity}, Req1, State) -> | ||
| #{opts := #{model := Model}} = State, | ||
| PersistedEntity = sumo:persist(Model, Entity), | ||
| ResBody = sr_json:encode(Model:to_json(PersistedEntity)), | ||
| Req2 = cowboy_req:set_resp_body(ResBody, Req1), | ||
| {true, Req2, State}. | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -2,6 +2,7 @@ | |
| { | ||
| incl_mods, | ||
| [ sr_entities_handler | ||
| , sr_single_entity_handler | ||
| , sr_json | ||
| , sumo_rest_doc | ||
| ] | ||
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Although it's true that at this point not much can go wrong, the other handle functions are wrapped in a try catch for unforseen exceptions and to return a proper 500 error, should this one do the same or is it overengineering?
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Our experience dictates that it's impossible to get this function to throw an exception. The main difference is the lack of access to databases or repositories here.