.NET Core 6配置NHibernate二级缓存时遇CacheFactory为空错误

错误原因 #

报错InvalidOperationException: CacheFactory is null...是因为CoreDistributedCacheProvider必须指定缓存工厂实现，原Web.Config中通过factory-class属性指定了内存缓存工厂，但迁移到Core后没有对应配置，导致NHibernate无法找到缓存工厂。

解决方案 #

提供两种可行方案，选一种即可：

方案1：将原XML配置迁移到appsettings.json #

1. 在appsettings.json中添加对应配置节点，和原Web.Config结构匹配：

{
  "coredistributedcache": {
    "factory-class": "NHibernate.Caches.CoreDistributedCache.Memory.MemoryFactory, NHibernate.Caches.CoreDistributedCache.Memory",
    "properties": {
      "expiration-scan-frequency": "00:10:00",
      "size-limit": "1048576",
      "cache.serializer": "NHibernate.Caches.Util.JsonSerializer.JsonCacheSerializer, NHibernate.Caches.Util.JsonSerializer"
    },
    "caches": [
      {
        "region": "foo",
        "expiration": "500",
        "sliding": "true"
      },
      {
        "region": "noExplicitExpiration",
        "sliding": "true"
      },
      {
        "region": "specificSerializer",
        "serializer": "NHibernate.Caches.Common.BinaryCacheSerializer, NHibernate.Caches.Common"
      }
    ]
  }
}

2. 修改Fluent NHibernate配置代码，读取并绑定配置：
   ASP.NET Core 6中IConfiguration已默认注册，直接在构造函数注入即可：

private readonly IConfiguration _configuration;

public YourSessionFactoryBuilder(IConfiguration configuration)
{
    _configuration = configuration;
}

public ISessionFactory BuildSessionFactory()
{
    // 读取appsettings中的缓存配置
    var cacheConfigSection = _configuration.GetSection("coredistributedcache");
    var sectionHandler = new CoreDistributedCacheSectionHandler();
    var cacheConfig = sectionHandler.Create(null, null, cacheConfigSection.GetRawJson());

    // 将配置传递给NHibernate缓存提供程序
    CoreDistributedCacheProvider.SetConfiguration(cacheConfig);

    var fluentConfiguration = Fluently.Configure()
        .Database(PostgreSQLConfiguration.Standard.Dialect<MySQL5Dialect>()
            .ConnectionString(x => x.Host("**")
                .Port(5432)
                .Database("**")
                .Username("**")
                .Password("**")))
        .Mappings(m => m.FluentMappings.AddFromAssembly(assembly).Conventions.Add(new DatabaseConvention()))
        .Cache(o => o.UseSecondLevelCache().UseQueryCache().ProviderClass<CoreDistributedCacheProvider>());

    return fluentConfiguration.BuildSessionFactory();
}

方案2：纯编程式配置（无需配置文件） #

直接在代码中指定缓存工厂和配置，更直观：

public ISessionFactory BuildSessionFactory()
{
    // 初始化内存缓存工厂
    var cacheFactory = new MemoryFactory();
    cacheFactory.Initialize(new Dictionary<string, string>
    {
        {"expiration-scan-frequency", "00:10:00"},
        {"size-limit", "1048576"},
        {"cache.serializer", "NHibernate.Caches.Util.JsonSerializer.JsonCacheSerializer, NHibernate.Caches.Util.JsonSerializer"}
    });

    // 设置缓存工厂到提供程序
    CoreDistributedCacheProvider.SetCacheFactory(cacheFactory);

    // 配置特定缓存区域（可选）
    CoreDistributedCacheProvider.SetRegionProperties("foo", new Dictionary<string, string>
    {
        {"expiration", "500"},
        {"sliding", "true"}
    });

    var fluentConfiguration = Fluently.Configure()
        .Database(PostgreSQLConfiguration.Standard.Dialect<MySQL5Dialect>()
            .ConnectionString(x => x.Host("**")
                .Port(5432)
                .Database("**")
                .Username("**")
                .Password("**")))
        .Mappings(m => m.FluentMappings.AddFromAssembly(assembly).Conventions.Add(new DatabaseConvention()))
        .Cache(o => o.UseSecondLevelCache().UseQueryCache().ProviderClass<CoreDistributedCacheProvider>());

    return fluentConfiguration.BuildSessionFactory();
}

注意事项 #

• 确保已安装对应NuGet包：NHibernate.Caches.CoreDistributedCache、NHibernate.Caches.CoreDistributedCache.Memory、NHibernate.Caches.Util.JsonSerializer。
• 原代码中PostgreSQLConfiguration搭配MySQL5Dialect是笔误，建议改为PostgreSQLDialect避免潜在问题。

内容的提问来源于stack exchange，提问作者tsiro