From d17fa2d8717cbe94268ed957b904d0dd19d74c3f Mon Sep 17 00:00:00 2001
From: Marc Worrell <marc@worrell.nl>
Date: Wed, 22 Jun 2022 09:58:05 +0200
Subject: [PATCH] Add on_request callback. (#41)

---
 README.md          | 6 ++++++
 src/cowmachine.erl | 8 ++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 5edd63d..185f299 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,12 @@ execute(Req, Env) ->
     RequestContext = cowmachine_req:init_context(Req, EnvController, #{}),
     % Set options for the cowmachine
     Options = #{
+        on_request =>
+            fun(Ctx) ->
+                % Perform anything after initialization of your request
+                % Examples are checking special cookies, changing headers, etc.
+                Ctx
+            end,
         on_welformed =>
             fun(Ctx) ->
                 % Perform anything after well-formedness check of your request
diff --git a/src/cowmachine.erl b/src/cowmachine.erl
index e617215..40cbc99 100644
--- a/src/cowmachine.erl
+++ b/src/cowmachine.erl
@@ -89,11 +89,15 @@ request_1(Controller, Req, Env, Options, Context) ->
     ReqResult = try
         EnvInit = cowmachine_req:init_env(Req, Env),
         Context1 = cowmachine_req:set_env(EnvInit, Context),
-        case cowmachine_decision_core:handle_request(State, Context1) of
+        Context2 = case maps:get(on_request, Options, undefined) of
+            undefined -> Context1;
+            FunReq when is_function(FunReq) -> FunReq(Context1)
+        end,
+        case cowmachine_decision_core:handle_request(State, Context2) of
             {_Finish, _StateResult, ContextResult} ->
                 ContextResult1 = case maps:get(on_handled, Options, undefined) of
                     undefined -> ContextResult;
-                    Fun when is_function(Fun) -> Fun(ContextResult)
+                    FunHandled when is_function(FunHandled) -> FunHandled(ContextResult)
                 end,
                 cowmachine_response:send_response(ContextResult1);
             {upgrade, UpgradeFun, _StateResult, ContextResult} ->