Set and Get cachelife time from appsettings in .NET core

Question

Can anyone please help me to Get Cacheexpiry time from appsettings in .NET core Application I have created a seperate class to handle caching , here i have written one method and everytime instead of calling database for credentials im just checking cache entry from this method . So here i just need to get cache time appsettings (Config file).

var cacheEntry = new MemoryCacheEntryOptions() .SetSlidingExpiration(here i need to get from config);

What all are the files i have to add code like getting value using get set and registering in startup. Im very much new to .Net core architecture.

Im using INmemoryCache

Answer 1

If you have a section in your config file, such as

"CacheOptions": {
    "AbsoluteExpirationRelativeToNow": 5,
    "SlidingExpiration": 1
}

Then what you would do in your ConfigureServices method is to make sure you call services.AddMemoryCache(); within it.

Example

public void ConfigureServices(IServiceCollection services)
{
 .....
services.AddMemoryCache();
 .....
 services.AddScoped<IDataExtract, DataExtract>();
 ....
}

Then, in a service, you can read the values.

 public class DataExtract : IDataExtract
{
    private readonly IConfiguration _config;
    private readonly ILogger<DataExtract> _logger;
    private readonly IMemoryCache _cache;
    private readonly MemoryCacheEntryOptions _options;

    public DataExtract(IConfiguration config, ILogger<DataExtract> logger, IMemoryCache cache)
    {
        _config = config;
        _logger = logger;
        _cache = cache;

        _options = new MemoryCacheEntryOptions
        {
            AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(
                Double.TryParse(config["CacheOptions:AbsoluteExpirationRelativeToNow"],
                    out var absoluteExpirationRelativeToNow)
                    ? absoluteExpirationRelativeToNow
                    : 5), // default cache will expire in 5 minutes
            SlidingExpiration =
                TimeSpan.FromMinutes(
                    Double.TryParse(config["CacheOptions:SlidingExpiration"], out var slidingExpiration)
                        ? slidingExpiration
                        : 1) // default cache will expire if inactive for 1 minute
        };
    }

    private ReportSettings GetReportSettings()
    {
        if (!_cache.TryGetValue("ReportSettings", out ReportSettings reportSettings))
        {
            _logger.LogInformation("Cache miss for ReportSettings ...loading from config file");
            reportSettings.ServerUrl = _config["Reporting:ServerUrl"];
            reportSettings.Username = _config["Reporting:Username"];
            reportSettings.Password = _config["Reporting:Password"];
            _cache.Set("ReportSettings", reportSettings, _options);
        }
        else
        {
            _logger.LogInformation("Cache hit for ReportSettings...serving data from cache");
        }

        return reportSettings;
    }
    
    .......
}

You can only read from appsettings.

If you want to change how the in-memory cache works, maybe storing the settings in a database or in a text file would be better.

For example when the application starts it reads from appsettings and then you have some logic that looks into another source for values.

This would mean that every other instantiation of the service would read the settings from another place other than appsettings.