Get value of vary-by attribute of <cache> tag helper from c#

Question

I want to clear the memory cache by a specific key generated by the tag helper. It is possible to clear the whole memory cache generated by the cache tag using the below code.

public partial class MemoryCacheManager : CacheKeyService, ILocker, IStaticCacheManager
{
    private readonly CacheTagHelperMemoryCacheFactory _factory;
    public MemoryCacheManager(AppSettings appSettings, IMemoryCache memoryCache, 
                        CacheTagHelperMemoryCacheFactory factory) : base(appSettings)
    {
        _memoryCache = memoryCache;
        _factory = factory;
    }

    public Task ClearAsync()
    {
        PropertyInfo prop = _factory.Cache.GetType().GetProperty("EntriesCollection", BindingFlags.Instance | BindingFlags.GetProperty | BindingFlags.NonPublic | BindingFlags.Public);
        var allInnerCacheTags = prop.GetValue(_factory.Cache) as ICollection;

        foreach (var item in allInnerCacheTags)
        {
            object cacheKeyOfTag = item.GetType().GetProperty("Key",  BindingFlags.Instance | BindingFlags.GetProperty | BindingFlags.NonPublic | BindingFlags.Public);
            _memoryCache.Remove(cacheKeyOfTag);
        }
    }
}

But I want to remove cache entry by specific key like the attached image.

Is there any way to get the value of the _varyBy.

Answer 1

I am able to get the value of the "_varyBy". Below code work for me net5.0. Assume also work for the net3.2

public partial class MemoryCacheManager
{
    private readonly CacheTagHelperMemoryCacheFactory _factory;
    private readonly IMemoryCache _memoryCache;

    public MemoryCacheManager(IMemoryCache memoryCache, 
                              CacheTagHelperMemoryCacheFactory factory)
    {
        _memoryCache = memoryCache;
        _factory = factory;
    }

    public void ClearCacheTagAsync(string cachekey)
    {
        PropertyInfo prop = _factory.Cache.GetType().GetProperty("EntriesCollection", BindingFlags.Instance | BindingFlags.GetProperty | BindingFlags.NonPublic | BindingFlags.Public);
        var allInnerCacheTags = prop.GetValue(_factory.Cache) as ICollection;
        foreach (var cacheEntry in allInnerCacheTags)
        {
            var theKeyValueOfEntry = cacheEntry.GetType().GetProperties().ToDictionary(property => property.Name, property => property.GetValue(cacheEntry));

            var item = theKeyValueOfEntry.FirstOrDefault();
            var cacheTag = ((CacheTagKey)item.Value);
            var field = cacheTag.GetType().GetField("_varyBy", BindingFlags.NonPublic | BindingFlags.Instance);
            var actualValue = field.GetValue(cacheTag);

            if (cachekey == actualValue.ToString())
            {
                _memoryCache.Remove(cacheEntry);
            }
        }
    }    
}