Added example of retrieving from a session.

doc.go

@@ -31,7 +31,12 @@ Let's start with an example that shows the sessions API in a nutshell:
 	func MyHandler(w http.ResponseWriter, r *http.Request) {
 		// Get a session. We're ignoring the error resulted from decoding an
 		// existing session: Get() always returns a session, even if empty.
-		session, _ := store.Get(r, "session-name")
+		session, err := store.Get(r, "session-name")
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+
 		// Set some session values.
 		session.Values["foo"] = "bar"
 		session.Values[42] = 43
@@ -66,7 +71,12 @@ flashes, call session.Flashes(). Here is an example:
 
 	func MyHandler(w http.ResponseWriter, r *http.Request) {
 		// Get a session.
-		session, _ := store.Get(r, "session-name")
+		session, err := store.Get(r, "session-name")
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+
 		// Get the previously flashes, if any.
 		if flashes := session.Flashes(); len(flashes) > 0 {
 			// Just print the flash values.
@@ -112,6 +122,26 @@ above we've passed it a pointer to a struct and a pointer to a custom type
 representing a map[string]interface. This will then allow us to serialise/deserialise
 values of those types to and from our sessions.
 
+Note that because session values are stored in a map[string]interface{}, there's
+a need to type-assert data when retrieving it. We'll use the Person struct we registered above:
+
+	func MyHandler(w http.ResponseWriter, r *http.Request) {
+		session, err := store.Get(r, "session-name")
+		if err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+
+		// Retrieve our struct and type-assert it
+		val := session.Values["person"]
+		var person &Person{}
+		if person, ok := val.(*Person); !ok {
+			// Handle the case that it's not an expected type
+		}
+
+		// Now we can use our person object
+	}
+
 By default, session cookies last for a month. This is probably too long for
 some cases, but it is easy to change this and other attributes during
 runtime. Sessions can be configured individually or the store can be