Interface IRequestContext

Namespace

SimpleMediator

Assembly

SimpleMediator.dll

Carries ambient context metadata through the mediator pipeline.

public interface IRequestContext

Examples

// Creating context
var context = RequestContext.Create()
    .WithUserId("user-123")
    .WithTenantId("tenant-abc")
    .WithIdempotencyKey("idempotency-xyz");

// Accessing in behaviors
public async ValueTask<Either<MediatorError, TResponse>> Handle(
    TRequest request,
    IRequestContext context,
    RequestHandlerCallback<TResponse> nextStep,
    CancellationToken cancellationToken)
{
    _logger.LogInformation(
        "Handling {Request} for user {UserId} (correlation: {CorrelationId})",
        typeof(TRequest).Name,
        context.UserId,
        context.CorrelationId);

    return await nextStep();
}

Remarks

Context is created once per request and flows through all behaviors, processors, and handlers. It provides access to cross-cutting concerns like correlation IDs, user identity, idempotency keys, and tenant information without polluting request types.

Immutable design: use With* methods to create modified copies.

Common Use Cases:

• Distributed tracing with correlation IDs
• Multi-tenant applications (tenant isolation)
• Idempotency checking (duplicate request detection)
• User context propagation (audit logs, authorization)
• Custom metadata for extensibility

Properties

CorrelationId

Correlation ID for distributed tracing.

string CorrelationId { get; }

Property Value

string

Remarks

Always present - auto-generated from Current or Guid if not provided. Use this for linking logs, traces, and metrics across services.

IdempotencyKey

Idempotency key for duplicate detection.

string? IdempotencyKey { get; }

Property Value

string

Remarks

null if idempotency is not applicable for this request. Used by idempotency behaviors to prevent duplicate processing of the same logical request. Typically extracted from HTTP headers (e.g., Idempotency-Key).

Metadata

Custom metadata for extensibility.

IReadOnlyDictionary<string, object?> Metadata { get; }

Property Value

IReadOnlyDictionary<string, object>

Remarks

Allows behaviors and processors to attach additional context that doesn't fit standard properties. Use WithMetadata(string, object?) to add entries.

TenantId

Tenant ID for multi-tenant applications.

string? TenantId { get; }

Property Value

string

Remarks

null if the application is not multi-tenant or tenant cannot be determined. Used for data isolation and tenant-specific logic.

Timestamp

Request timestamp (UTC).

DateTimeOffset Timestamp { get; }

Property Value

DateTimeOffset

Remarks

Captured when the context is created, represents the start of request processing. Useful for time-based logic, audit trails, and latency measurements.

UserId

User ID initiating the request.

string? UserId { get; }

Property Value

string

Remarks

null if the request is unauthenticated. Typically extracted from claims principal in ASP.NET Core applications.

Methods

WithIdempotencyKey(string?)

Creates a new context with updated idempotency key.

IRequestContext WithIdempotencyKey(string? idempotencyKey)

Parameters

idempotencyKey string

Idempotency key to set.

Returns

IRequestContext

New context instance with the idempotency key updated.

Remarks

Follows immutable pattern - original context is not modified. Useful in pre-processors that extract idempotency headers.

WithMetadata(string, object?)

Creates a new context with additional metadata.

IRequestContext WithMetadata(string key, object? value)

Parameters

key string

Metadata key.

value object

Metadata value.

Returns

IRequestContext

New context instance with the metadata added.

Remarks

Follows immutable pattern - original context is not modified.

WithTenantId(string?)

Creates a new context with updated tenant ID.

IRequestContext WithTenantId(string? tenantId)

Parameters

tenantId string

Tenant ID to set.

Returns

IRequestContext

New context instance with the tenant ID updated.

Remarks

Follows immutable pattern - original context is not modified. Useful in pre-processors that determine tenant from request data or claims.

WithUserId(string?)

Creates a new context with updated user ID.

IRequestContext WithUserId(string? userId)

Parameters

userId string

User ID to set.

Returns

IRequestContext

New context instance with the user ID updated.

Remarks

Follows immutable pattern - original context is not modified. Useful in pre-processors that extract user identity.