Object Persistence

In this lesson, we will learn how to store class objects, including object storage and retrieval.

This code demonstrates Memcached storing primitive types (int/bool) and custom Class objects, and highlights a very common pitfall:

Custom entity classes must be marked with the [Serializable] attribute. Otherwise serialization will fail and null will be returned when reading the object.

Wrong Implementation

static void Main(string[] args)
{
    MemcachedClient mClient = new MemcachedClient();

    // Store and read primitive types (int, bool are natively supported, no serialization attribute required)
    mClient.Store(StoreMode.Set, "clicks", 1);
    var clicks = mClient.Get<int>("clicks");

    mClient.Store(StoreMode.Set, "isOk", true);
    var isOk = mClient.Get<bool>("isOk");

    // Store custom object
    var person = new Person { Id = 1, Name = "Jackson", AddTime = DateTime.Now };
    mClient.Store(StoreMode.Set, "person", person);
    var p = mClient.Get<Person>("person"); // Will get null here
    Console.Read();
}

// 【Wrong】Missing [Serializable]
class Person
{
    public int Id { set; get; }
    public string Name { set; get; }
    public DateTime AddTime { set; get; }
}Code language: JavaScript (javascript)

Observed Behavior

var p = mClient.Get<Person>("person"); returns null.
Cause: EnyimMemcached uses .NET binary serialization by default for object persistence. Classes without the [Serializable] attribute cannot be serialized and cannot be deserialized properly after being cached.

Correct Implementation

Add the serialization attribute to your entity class:

[Serializable] // Mandatory attribute
public class Person
{
    public int Id { set; get; }
    public string Name { set; get; }
    public DateTime AddTime { set; get; }
}Code language: JavaScript (javascript)

Once added, Get<Person>("person") will correctly return the object instance.

Additional Notes

// Generic Get: Recommended usage, automatic type conversion
var p = mClient.Get<Person>("person"); 

// Non‑generic Get: Returns object, manual cast required afterwards
var p2 = mClient.Get("person");Code language: JavaScript (javascript)

• Get<T>(key): Generic method, preferred. Returns type‑specific default value on failure (null for reference types)
• Get(key): Returns raw object, you must cast it manually

Full Working Sample

using Enyim.Caching;
using Enyim.Caching.Memcached;
using System;

[Serializable]
public class Person
{
    public int Id { set; get; }
    public string Name { set; get; }
    public DateTime AddTime { set; get; }
}

class Program
{
    static void Main(string[] args)
    {
        MemcachedClient mClient = new MemcachedClient();

        mClient.Store(StoreMode.Set, "clicks", 1);
        var clicks = mClient.Get<int>("clicks");

        mClient.Store(StoreMode.Set, "isOk", true);
        var isOk = mClient.Get<bool>("isOk");

        var person = new Person { Id = 1, Name = "Jackson", AddTime = DateTime.Now };
        mClient.Store(StoreMode.Set, "person", person);

        var p = mClient.Get<Person>("person");
        Console.WriteLine(p.Name); // Output: Jackson

        Console.Read();
    }
}Code language: JavaScript (javascript)

Object Persistence