Add explicit ignoring of some event types during webhook processing

Author: begedin

lib/code_corps/stripe_service/webhook_processing/event_handler.ex

@@ -1,13 +1,18 @@
 defmodule CodeCorps.StripeService.WebhookProcessing.EventHandler do
   alias CodeCorps.{StripeEvent, Repo}
-  alias CodeCorps.StripeService.WebhookProcessing.{ConnectEventHandler, PlatformEventHandler}
   alias CodeCorps.StripeService.Adapters.StripeEventAdapter
+  alias CodeCorps.StripeService.WebhookProcessing.{
+    ConnectEventHandler, IgnoredEventHandler, PlatformEventHandler
+  }
 
-  def handle(%Stripe.Event{} = api_event, handler) do
+  def handle(%Stripe.Event{type: type} = api_event, handler) do
     with {:ok, endpoint} <- infer_endpoint_from_handler(handler),
          {:ok, %StripeEvent{} = local_event} <- find_or_create_event(api_event, endpoint)
     do
-      call_handler(api_event, local_event, handler)
+      case IgnoredEventHandler.should_handle?(type) do
+        true -> call_ignored_handler(local_event)
+        false -> call_handler(api_event, local_event, handler)
+      end
     else
       failure -> failure
     end
@@ -34,6 +39,8 @@ defmodule CodeCorps.StripeService.WebhookProcessing.EventHandler do
     end
   end
 
+  defp call_ignored_handler(local_event), do: IgnoredEventHandler.handle(local_event)
+
   defp call_handler(api_event, local_event, handler) do
     # results are multiple, so we convert the tuple to list for easier matching
     case api_event |> handler.handle_event |> Tuple.to_list do

lib/code_corps/stripe_service/webhook_processing/ignored_event_handler.ex

@@ -0,0 +1,55 @@
+defmodule CodeCorps.StripeService.WebhookProcessing.IgnoredEventHandler do
+  alias CodeCorps.{StripeEvent, Repo}
+
+  @ignored_event_types [
+    "application_fee.created",
+    "customer.created",
+    "customer.source.created",
+    "customer.subscription.created",
+    "invoice.created",
+    "plan.created"
+  ]
+
+  @doc """
+  Determines if an event type should be handled by __MODULE__
+
+  Returns true or false depending on specified type
+  """
+  @spec should_handle?(String.t) :: boolean
+  def should_handle?(type), do: Enum.member?(ignored_event_types, type)
+
+  @doc """
+  Returns a list of event types which are being explicitly ignored by the application.
+  """
+  @spec ignored_event_types :: list
+  def ignored_event_types, do: @ignored_event_types
+
+  @doc """
+  Takes in a `CodeCorps.StripeEvent` to be processed as "ignored".
+  Determines the reason for ignoring the event, then updates the record to
+  `status: "ignored"` and `ignored_reason: inferred_message`
+
+  Returns `{:ok, %CodeCorps.StripeEvent{}}
+  """
+  @spec handle(StripeEvent.t) :: {:ok, StripeEvent.t}
+  def handle(%StripeEvent{type: type} = local_event) do
+    with ignored_reason <- get_reason(type) do
+      local_event |> set_ignored(ignored_reason)
+    end
+  end
+
+  @spec get_reason(String.t) :: String.t
+  defp get_reason("application_fee.created"), do: "We don't make use of the application fee object."
+  defp get_reason("customer.created"), do: "Customers are only created from the client."
+  defp get_reason("customer.source.created"), do: "Cards are only created from the client. No need to handle"
+  defp get_reason("customer.subscription.created"), do: "Subscriptions are only created from the client."
+  defp get_reason("invoice.created"), do: "We prefer to handle other lifecycle events for invoices, like payment_succeeded."
+  defp get_reason("plan.created"), do: "Plans are only created from the client."
+
+  @spec set_ignored(StripeEvent.t, String.t) :: {:ok, StripeEvent.t}
+  defp set_ignored(%StripeEvent{} = local_event, ignored_reason) do
+    local_event
+    |> StripeEvent.update_changeset(%{status: "ignored", ignored_reason: ignored_reason})
+    |> Repo.update
+  end
+end

priv/repo/migrations/20170115230549_add_ignored_reason_to_stripe_events.exs

@@ -0,0 +1,9 @@
+defmodule CodeCorps.Repo.Migrations.AddIgnoredReasonToStripeEvents do
+  use Ecto.Migration
+
+  def change do
+    alter table(:stripe_events) do
+      add :ignored_reason, :string
+    end
+  end
+end

priv/repo/structure.sql

@@ -2,8 +2,8 @@
 -- PostgreSQL database dump
 --
 
--- Dumped from database version 9.5.4
--- Dumped by pg_dump version 9.5.4
+-- Dumped from database version 9.5.1
+-- Dumped by pg_dump version 9.5.1
 
 SET statement_timeout = 0;
 SET lock_timeout = 0;
@@ -739,7 +739,8 @@ CREATE TABLE stripe_events (
     endpoint character varying(255) NOT NULL,
     user_id character varying(255),
     object_id character varying(255) NOT NULL,
-    object_type character varying(255) NOT NULL
+    object_type character varying(255) NOT NULL,
+    ignored_reason character varying(255)
 );
 
 
@@ -2277,5 +2278,5 @@ ALTER TABLE ONLY user_skills
 -- PostgreSQL database dump complete
 --
 
-INSERT INTO "schema_migrations" (version) VALUES (20160723215749), (20160804000000), (20160804001111), (20160805132301), (20160805203929), (20160808143454), (20160809214736), (20160810124357), (20160815125009), (20160815143002), (20160816020347), (20160816034021), (20160817220118), (20160818000944), (20160818132546), (20160820113856), (20160820164905), (20160822002438), (20160822004056), (20160822011624), (20160822020401), (20160822044612), (20160830081224), (20160830224802), (20160911233738), (20160912002705), (20160912145957), (20160918003206), (20160928232404), (20161003185918), (20161019090945), (20161019110737), (20161020144622), (20161021131026), (20161031001615), (20161121005339), (20161121014050), (20161121043941), (20161121045709), (20161122015942), (20161123081114), (20161123150943), (20161124085742), (20161125200620), (20161126045705), (20161127054559), (20161205024856), (20161207112519), (20161209192504), (20161212005641), (20161214005935), (20161215052051), (20161216051447), (20161218005913), (20161219160401), (20161219163909), (20161220141753), (20161221085759), (20161226213600), (20161231063614), (20170102130055), (20170102181053), (20170104113708), (20170104212623), (20170104235423), (20170106013143), (20170115035159);
+INSERT INTO "schema_migrations" (version) VALUES (20160723215749), (20160804000000), (20160804001111), (20160805132301), (20160805203929), (20160808143454), (20160809214736), (20160810124357), (20160815125009), (20160815143002), (20160816020347), (20160816034021), (20160817220118), (20160818000944), (20160818132546), (20160820113856), (20160820164905), (20160822002438), (20160822004056), (20160822011624), (20160822020401), (20160822044612), (20160830081224), (20160830224802), (20160911233738), (20160912002705), (20160912145957), (20160918003206), (20160928232404), (20161003185918), (20161019090945), (20161019110737), (20161020144622), (20161021131026), (20161031001615), (20161121005339), (20161121014050), (20161121043941), (20161121045709), (20161122015942), (20161123081114), (20161123150943), (20161124085742), (20161125200620), (20161126045705), (20161127054559), (20161205024856), (20161207112519), (20161209192504), (20161212005641), (20161214005935), (20161215052051), (20161216051447), (20161218005913), (20161219160401), (20161219163909), (20161220141753), (20161221085759), (20161226213600), (20161231063614), (20170102130055), (20170102181053), (20170104113708), (20170104212623), (20170104235423), (20170106013143), (20170115035159), (20170115230549);
 

test/lib/code_corps/stripe_service/webhook_processing/event_handler_test.exs

@@ -234,4 +234,14 @@ defmodule CodeCorps.StripeService.WebhookProcessing.EventHandlerTest do
       assert {:error, :already_processing} == EventHandler.handle(event, PlatformEventHandler)
     end
   end
+
+  describe "ignored events" do
+    test "properly sets as ignored" do
+      event = build_event("application_fee.created")
+      {:ok, event} = EventHandler.handle(event, PlatformEventHandler)
+
+      assert event.status == "ignored"
+      assert event.ignored_reason
+    end
+  end
 end

test/lib/code_corps/stripe_service/webhook_processing/ignored_event_handler_test.exs

@@ -0,0 +1,30 @@
+defmodule CodeCorps.StripeService.WebhookProcessing.IgnoredEventHandlerTest do
+  use CodeCorps.ModelCase
+
+  alias CodeCorps.StripeService.WebhookProcessing.IgnoredEventHandler
+
+  defp ignored?(type) do
+    event = insert(:stripe_event, type: type)
+    {:ok, event} = IgnoredEventHandler.handle(event)
+
+    event.ignored_reason && event.status == "ignored"
+  end
+
+  describe "handle/1" do
+    test "ignores events from the ignored events list" do
+      IgnoredEventHandler.ignored_event_types
+      |> Enum.each(fn(type) -> assert ignored?(type) end)
+
+      assert_raise(FunctionClauseError, fn -> ignored?("some.other.type") end)
+    end
+  end
+
+  describe "should_handle?/1" do
+    test "returns true for types from the ignored list" do
+      IgnoredEventHandler.ignored_event_types
+      |> Enum.each(fn(type) -> assert IgnoredEventHandler.should_handle?(type) end)
+
+      refute IgnoredEventHandler.should_handle?("some.other.type")
+    end
+  end
+ end

web/models/stripe_event.ex

@@ -24,6 +24,7 @@ defmodule CodeCorps.StripeEvent do
   schema "stripe_events" do
     field :endpoint, :string, null: false
     field :id_from_stripe, :string, null: false
+    field :ignored_reason, :string
     field :object_id, :string
     field :object_type, :string
     field :status, :string, default: "unprocessed"
@@ -54,7 +55,7 @@ defmodule CodeCorps.StripeEvent do
   """
   def update_changeset(struct, params) do
     struct
-    |> cast(params, [:status])
+    |> cast(params, [:ignored_reason, :status])
     |> validate_required([:status])
     |> validate_inclusion(:status, states)
   end
@@ -64,6 +65,6 @@ defmodule CodeCorps.StripeEvent do
   end
 
   defp states do
-    ~w{ errored processed processing unhandled unprocessed }
+    ~w{ errored ignored processed processing unhandled unprocessed }
   end
 end