IDistributedCache 可用但数据不再在缓存中？

Question

我在我的 .Net Core 3 网站中使用 services.AddDistributedMemoryCache() api startup.cs class。当我第一次设置缓存时：

public void SetCommandEventMappingCache(IServiceCollection serviceCollection)
{
    var cache = serviceCollection.BuildServiceProvider().GetService<IDistributedCache>();

    var mappingList = new List<CommandEventMapping>()
    {
        new CommandEventMapping()
        {
            ActionType = "add",
            GrowFlowCommand = new AddEmployee(),
            GrowFlowEvent = "EmployeeAdded",
            TraceabilityCommand = "employee_add"
        }
    };

    cache.Set<List<CommandEventMapping>>(
        "command_event_mappings", mappingList,new DistributedCacheEntryOptions()
    {
        AbsoluteExpiration = DateTimeOffset.Now.AddDays(1)
    });

    //I am able to get back the command_event_mappings here.
    //Once the IDistributedCache is injected. the data is lost
    var commandMapping = cache.Get<List<CommandEventMapping>>("command_event_mappings");
}

在我见过的所有示例中，通常都是这样设置的。唯一的区别是我为 Set<T> 和 Get<T> 添加了一对扩展。我确实在没有新扩展方法的情况下进行了尝试，但结果相同。实际注入时的IDistributedCache是可用的，但是之前缓存的数据没有了。这是我如何注入它的示例。

public LegacyCommandBus(IServiceProvider provider, IDistributedCache cache,
    ITraceabilityTenantService tenantService, IHttpClientFactory httpClientFactory)
    : base(provider)
{
    _provider = provider;
    _cache = cache;
    _tenantService = tenantService;
    _httpClientFactory = httpClientFactory; 
    //This is null
    _commandEventMappings = cache.Get<List<CommandEventMapping>>("command_event_mappings");
}

Answer 1

var cache = serviceCollection.BuildServiceProvider().GetService<IDistributedCache>();

每次你调用 BuildServiceProvider()，你都会生成一个新的容器，它有自己的一组单例（不同于使用内置 DI 注入的单例）。

解决方案是在 Startup class.

中解析 Configure 中的 IDistributedCache 实例

public void Configure(IApplicationBuilder app, IDistributedCache cache) { 
    //...
}

IDistributedCache 可用但数据不再在缓存中？

IDistributedCache available but the data is no longer in the cache?

c#

dependency-injection

.net-core

distributed-caching