IMemoryCache get return null after setting a value asp.net core 2.2

Question

我正在尝试在我的 ASP.NET CORE 2.2 Web API 应用程序中使用 IMemoryCache 服务。我在启动时的 ConfigureServices 函数中添加了服务（.AddMemoryCache()）。在开始使用它之前，我决定测试一下，看看我是否可以成功地设置一个值并使用该服务检索它。不幸的是，每当我设置一个值然后尝试检索它时，API 响应 return 204 找不到内容。我做错了什么，请帮忙。谢谢。

public void ConfigureServices(IServiceCollection services)
    {
        services.AddMemoryCache();
        services.AddMvc();
    }

然后在我的 TestController

namespace JwtTut.Controllers
{
    [Route("api")]
    public class TestController : Controller
    {
    private readonly ILogger _logger;
    private readonly ApplicationDbContext _context;
    private readonly UserManager<IdentityUser> userManager;
    private readonly RoleManager<IdentityRole> roleManager;
    private readonly IIdentityService _identityService;
    private IMemoryCache _memoryCache;

    public TestController(ILogger<TestController> logger, ApplicationDbContext context,
        UserManager<IdentityUser> userManager, RoleManager<IdentityRole> roleManager,
        IIdentityService identityService, IMemoryCache memoryCache)
    {
        _logger = logger;
        _context = context;
        this.userManager = userManager;
        this.roleManager = roleManager;
        _identityService = identityService;
        _memoryCache = memoryCache;
    }

    [HttpGet("user-claims")]
    public IActionResult GetUserClaims()
    {
        var randomList = new List<string>();
        for (int i = 0; i < 20; i++)
        {
            randomList.Add($"{i}");
        }

        _memoryCache.Set("randomLIst", randomList);
        var fromCache = _memoryCache.Get<string>("randomList");

        return Ok(fromCache);
    }
}

}

我正在使用 api/user-claims 来测试 IMemoryCache 服务

Answer 1

看下面两行。您用于设置缓存的密钥（randomLIst）与您用于获取缓存的密钥（randomList）不同：

_memoryCache.Set("randomLIst", randomList);
var fromCache = _memoryCache.Get<string>("randomList");

更正：

_memoryCache.Set("randomList", randomList);
var fromCache = _memoryCache.Get<string>("randomList");

我建议您为缓存键制作一个单独的实用程序 class 以避免印刷错误。

IMemoryCache get return null after setting a value asp.net core 2.2

IMemoryCache get return null after setting a value asp.net core 2.2

caching

asp.net-core

asp.net-core-2.1