Added HttpContext helper extension methods

Added two more HttpContext extension methods, which make accessing Cookie values and Form values more F# idiomatic.

RELEASE_NOTES.md

@@ -1,12 +1,18 @@
 Release Notes
 =============
 
-## 3.5.1
+## 3.6.0
 
 #### Bug fixes
 
 - Fixed a bug in Giraffe's model binding to not try to set read only properties anymore.
 
+#### New features
+
+- Added two new `HttpContext` extension methods to retrieve cookie and form values:
+    - `GetCookieValue (key : string)`
+    - `GetFormValue (key : string)`
+
 ## 3.5.0
 
 #### New features

src/Giraffe/Core.fs

@@ -227,6 +227,43 @@ type HttpContext with
         | true, value -> Ok (value.ToString())
         | _           -> Error (sprintf "Query string value '%s' is missing." key)
 
+    /// **Description**
+    ///
+    /// Retrieves the `string` value of a cookie from the request.
+    ///
+    /// **Parameters**
+    ///
+    /// `key`: The name of the cookie.
+    ///
+    /// **Output**
+    ///
+    /// Returns `Some string` if the cookie was set, otherwise returns `None`.
+    ///
+    member this.GetCookieValue (key : string) =
+        match this.Request.Cookies.TryGetValue key with
+        | true , cookie -> Some cookie
+        | false, _      -> None
+
+    /// **Description**
+    ///
+    /// Retrieves the `string` value of a form parameter from the request.
+    ///
+    /// **Parameters**
+    ///
+    /// `key`: The name of the form parameter.
+    ///
+    /// **Output**
+    ///
+    /// Returns `Some string` if the form parameter was set, otherwise returns `None`.
+    ///
+    member this.GetFormValue (key : string) =
+        match this.Request.HasFormContentType with
+        | false -> None
+        | true  ->
+            match this.Request.Form.TryGetValue key with
+            | true , value -> Some (value.ToString())
+            | false, _     -> None
+
 // ---------------------------
 // HttpHandler definition
 // ---------------------------

src/Giraffe/Giraffe.fsproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <!-- General -->
     <AssemblyName>Giraffe</AssemblyName>
-    <Version>3.5.1</Version>
+    <Version>3.6.0</Version>
     <Description>A native functional ASP.NET Core web framework for F# developers.</Description>
     <Copyright>Copyright 2018 Dustin Moris Gorski</Copyright>
     <Authors>Dustin Moris Gorski and contributors</Authors>