Custom Context Type

When the built-in context types do not meet the requirements, you can refer to the implementation of EnvContext to implement your own context type.

How to Implement a Custom Context Type

1. Define the context type

   public class CustomContext
   {
       // The context will be stored as a key-value pair, and this key is the ContextKey
       public static string ContextKey { get; set; } = "x-custom-context"; 
   
       public CustomContext(string data)
       {
           Data = data;
       }
   
       public string Data { get; private set; }
   }
   

2. Implement the IContextCarrierHandler interface

   public class CustomContextCarrierHandler : IContextCarrierHandler
   {
       public Type ContextType => typeof(CustomContext);
   
       public void Inject(IContextCarrier carrier, object? context)
       {
           if (context != null)
           {
               carrier.Set(CustomContext.ContextKey, ((CustomContext)context).Data);
           }
       }
   
       public object? Initial()
       {
           return null;
       }
   }
   

3. Implement the IContextSourceHandler interface

   public class CustomContextSourceHandler : IContextSourceHandler
   {
       public Type ContextType => typeof(CustomContext);
   
       public object? Extract(IContextSource source)
       {
           var data = source.Get(CustomContext.ContextKey);
           return string.IsNullOrEmpty(data) ? null : new CustomContext(data);
       }
   }
   

4. Add context type registration

   public static class ServiceCollectionExtensions
   {
       public static IServiceCollection AddCustomContext(this IServiceCollection services)
       {
           services.AddContextCore();
           services.TryAddSingleton<IContextCarrierHandler, CustomContextCarrierHandler>();
           services.TryAddSingleton<IContextSourceHandler, CustomContextSourceHandler>();
           return services;
       }
   }
   

5. Register the context type in Program.cs

   builder.Services.AddContext()  
       .AddEnvContext()    
       .AddTenantContext() 
       .AddCustomContext()  // Add custom context
       .AddCapContextProcessor();