public ValueTask <TargetingContext> GetContextAsync()
{
HttpContext httpContext = _httpContextAccessor.HttpContext;
//
// Try cache lookup
if (httpContext.Items.TryGetValue(TargetingContextLookup, out object value))
{
return(new ValueTask <TargetingContext>((TargetingContext)value));
}
ClaimsPrincipal user = httpContext.User;
List <string> groups = user.Claims.Where(claim => claim.Type == ClaimTypes.GroupName)
.Select(claim => claim.Value).ToList();
//
// This application expects groups to be specified in the user's claims
//
// Build targeting context based off user info
var targetingContext = new TargetingContext
{
UserId = user.Identity.Name,
Groups = groups
};
//
// Cache for subsequent lookup
httpContext.Items[TargetingContextLookup] = targetingContext;
return(new ValueTask <TargetingContext>(targetingContext));
}
/// <summary>
/// Performs a targeting evaluation using the current <see cref="TargetingContext"/> to determine if a feature should be enabled.
/// </summary>
/// <param name="context">The feature evaluation context.</param>
/// <exception cref="ArgumentNullException">Thrown if <paramref name="context"/> is null.</exception>
/// <returns>True if the feature is enabled, false otherwise.</returns>
public async Task <bool> EvaluateAsync(FeatureFilterEvaluationContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
//
// Acquire targeting context via accessor
TargetingContext targetingContext = await _contextAccessor.GetContextAsync().ConfigureAwait(false);
//
// Ensure targeting can be performed
if (targetingContext == null)
{
_logger.LogWarning("No targeting context available for targeting evaluation.");
return(false);
}
//
// Utilize contextual filter for targeting evaluation
return(await _contextualFilter.EvaluateAsync(context, targetingContext).ConfigureAwait(false));
}