From 766847a38bea06f1968014fddee1b5d8471ced35 Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Fri, 24 Feb 2017 16:37:59 +0000
Subject: [PATCH] Add helper functions

- Add `NewJSONRequestHandler` which takes a `func` and turns it into
  a `JSONRequestHandler`. This prevents the same wrapping code being
  written over and over.
- Make `GetLogger(Context)` always return a logger, so callers don't
  need to constantly `nil` check.
---
 context.go   |  6 ++++--
 json.go      | 15 +++++++++++++++
 json_test.go |  4 ++--
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/context.go b/context.go
index d8def4f..f2477a5 100644
--- a/context.go
+++ b/context.go
@@ -25,11 +25,13 @@ func GetRequestID(ctx context.Context) string {
 // ctxValueLogger is the key to extract the logrus Logger.
 const ctxValueLogger = contextKeys("logger")
 
-// GetLogger retrieves the logrus logger from the supplied context. Returns nil if there is no logger.
+// GetLogger retrieves the logrus logger from the supplied context. Always returns a logger,
+// even if there wasn't one originally supplied.
 func GetLogger(ctx context.Context) *log.Entry {
 	l := ctx.Value(ctxValueLogger)
 	if l == nil {
-		return nil
+		// Always return a logger so callers don't need to constantly nil check.
+		return log.WithField("context", "missing")
 	}
 	return l.(*log.Entry)
 }
diff --git a/json.go b/json.go
index b0834ea..46c5396 100644
--- a/json.go
+++ b/json.go
@@ -58,6 +58,21 @@ type JSONRequestHandler interface {
 	OnIncomingRequest(req *http.Request) JSONResponse
 }
 
+// jsonRequestHandlerWrapper is a wrapper to allow in-line functions to conform to util.JSONRequestHandler
+type jsonRequestHandlerWrapper struct {
+	function func(req *http.Request) JSONResponse
+}
+
+// OnIncomingRequest implements util.JSONRequestHandler
+func (r *jsonRequestHandlerWrapper) OnIncomingRequest(req *http.Request) JSONResponse {
+	return r.function(req)
+}
+
+// NewJSONRequestHandler converts the given OnIncomingRequest function into a JSONRequestHandler
+func NewJSONRequestHandler(f func(req *http.Request) JSONResponse) JSONRequestHandler {
+	return &jsonRequestHandlerWrapper{f}
+}
+
 // Protect panicking HTTP requests from taking down the entire process, and log them using
 // the correct logger, returning a 500 with a JSON response rather than abruptly closing the
 // connection. The http.Request MUST have a ctxValueLogger.
diff --git a/json_test.go b/json_test.go
index 687db27..3ce03a8 100644
--- a/json_test.go
+++ b/json_test.go
@@ -164,8 +164,8 @@ func TestGetLogger(t *testing.T) {
 
 	noLoggerInReq, _ := http.NewRequest("GET", "http://example.com/foo", nil)
 	ctxLogger = GetLogger(noLoggerInReq.Context())
-	if ctxLogger != nil {
-		t.Errorf("TestGetLogger wanted nil logger, got '%v'", ctxLogger)
+	if ctxLogger == nil {
+		t.Errorf("TestGetLogger wanted logger, got nil")
 	}
 }