database: add middleware

database/context.go

@@ -6,12 +6,6 @@ import (
 	"errors"
 )
 
-var dbCtxKey = &contextKey{"database"}
-
-type contextKey struct {
-	name string
-}
-
 func Context(ctx context.Context, db *sql.DB) context.Context {
 	return context.WithValue(ctx, dbCtxKey, db)
 }

database/middleware.go

@@ -0,0 +1,22 @@
+package database
+
+import (
+	"database/sql"
+	"net/http"
+)
+
+var dbCtxKey = &contextKey{"database"}
+
+type contextKey struct {
+	name string
+}
+
+func Middleware(db *sql.DB) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			ctx := Context(r.Context(), db)
+			r = r.WithContext(ctx)
+			next.ServeHTTP(w, r)
+		})
+	}
+}