Cookies: Ability to set custom cookie encoders to encode the cookie's value before sent by ctx.SetCookie and ctx.SetCookieKV and cookie decoders to decode the cookie's value when retrieving from ctx.GetCookie. That was the second and final part relative to a community's question at: https://github.com/kataras/iris/issues/1018

Former-commit-id: 53b6810076c8db8646df335d57a30c78b23cd9b8

context/context.go

@@ -3058,6 +3058,64 @@ func CookieHTTPOnly(httpOnly bool) CookieOption {
 	}
 }
 
+type (
+	// CookieEncoder should encode the cookie value.
+	// Should accept as first argument the cookie name
+	// and as second argument the cookie value ptr.
+	// Should return an encoded value or an empty one if encode operation failed.
+	// Should return an error if encode operation failed.
+	//
+	// Note: Errors are not printed, so you have to know what you're doing,
+	// and remember: if you use AES it only supports key sizes of 16, 24 or 32 bytes.
+	// You either need to provide exactly that amount or you derive the key from what you type in.
+	//
+	// See `CookieDecoder` too.
+	CookieEncoder func(cookieName string, value interface{}) (string, error)
+	// CookieDecoder should decode the cookie value.
+	// Should accept as first argument the cookie name,
+	// as second argument the encoded cookie value and as third argument the decoded value ptr.
+	// Should return a decoded value or an empty one if decode operation failed.
+	// Should return an error if decode operation failed.
+	//
+	// Note: Errors are not printed, so you have to know what you're doing,
+	// and remember: if you use AES it only supports key sizes of 16, 24 or 32 bytes.
+	// You either need to provide exactly that amount or you derive the key from what you type in.
+	//
+	// See `CookieEncoder` too.
+	CookieDecoder func(cookieName string, cookieValue string, v interface{}) error
+)
+
+// CookieEncode is a `CookieOption`.
+// Provides encoding functionality when adding a cookie.
+// Accepts a `CookieEncoder` and sets the cookie's value to the encoded value.
+// Users of that is the `SetCookie` and `SetCookieKV`.
+//
+// Example: https://github.com/kataras/iris/tree/master/_examples/cookies/securecookie
+func CookieEncode(encode CookieEncoder) CookieOption {
+	return func(c *http.Cookie) {
+		newVal, err := encode(c.Name, c.Value)
+		if err != nil {
+			c.Value = ""
+		} else {
+			c.Value = newVal
+		}
+	}
+}
+
+// CookieDecode is a `CookieOption`.
+// Provides decoding functionality when retrieving a cookie.
+// Accepts a `CookieDecoder` and sets the cookie's value to the decoded value before return by the `GetCookie`.
+// User of that is the `GetCookie`.
+//
+// Example: https://github.com/kataras/iris/tree/master/_examples/cookies/securecookie
+func CookieDecode(decode CookieDecoder) CookieOption {
+	return func(c *http.Cookie) {
+		if err := decode(c.Name, c.Value, &c.Value); err != nil {
+			c.Value = ""
+		}
+	}
+}
+
 // SetCookie adds a cookie.
 // Use of the "options" is not required, they can be used to amend the "cookie".
 //
@@ -3111,19 +3169,6 @@ func (ctx *context) GetCookie(name string, options ...CookieOption) string {
 		return ""
 	}
 
-	// TODO:
-	// Q: Why named as `CookieOption` and not like `CookieInterceptor`?
-	// A: Because an interceptor would be able to modify the cookie AND stop the 'x' operation, but we don't want to cancel anything.
-	//
-	// Q: Why "Cookie Options" here?
-	// A: Because of the future suport of cookie encoding like I did with sessions.
-	//    Two impl ideas:
-	//     - Do it so each caller of `GetCookie/SetCookieKV/SetCookie` can have each own encoding or share one, no limit.
-	//     - Do it so every of the above three methods will use the same encoding, therefore to the Application's level, limit per Iris app.
-	//    We'll see...
-	//
-	// Finally, I should not forget to add links for the new translated READMEs(2) and push a new version with the minor changes so far,
-	// API is stable, so relax and do it on the next commit tomorrow, need sleep.
 	for _, opt := range options {
 		opt(cookie)
 	}