HttpContextExtensions.md

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2	Access correlation id of an HttpContext

How to access the correlation id of an HttpContext

GetCorrelationIdAccessor

Accessing the correlation id of an HttpContext is done with the ICorrelationIdAccessor returned by the GetCorrelationIdAccessor extension method, from the RockLib.DistributedTracing.AspNetCore namespace.

ICorrelationIdAccessor accessor = HttpContext.GetCorrelationIdAccessor();
string correlationId = accessor.CorrelationId;

Each time the GetCorrelationIdAccessor extension method is called on the same instance of HttpContext, the same instance of ICorrelationIdAccessor is returned. This is because the accessor is stored in the HttpContext.Items dictionary.

The first time the GetCorrelationIdAccessor extension method is called, an attempt is made to set the value of its CorrelationId property from the "X-Correlation-Id" header from the HttpContext.Request.Headers. If no such header exists, then the value is set to a new GUID value.

A different header (besides "X-Correlation-Id") can be specified by passing a value to the optional correlationIdHeader parameter:

ICorrelationIdAccessor accessor = HttpContext.GetCorrelationIdAccessor("MyCorrelationIdHeader");

GetCorrelationId

This extension method, which has the same optional correlationIdHeader parameter as the above GetCorrelationIdAccessor extension method, returns the value of the CorrelationId property of the ICorrelationIdAccessor returned by a call to GetCorrelationIdAccessor.

string correlationId = HttpContext.GetCorrelationId();

SetCorrelationId

This extension method is exactly like GetCorrelationId, except it sets the CorrelationId property of the ICorrelationIdAccessor instead of getting it.

HttpContext.SetCorrelationId("MyCorrelationId");