ExceptionHandler

ExceptionHandler is the static error-translation type that JsonHttpClient calls after every request to convert an unsuccessful HTTP response into a specific, typed SAIFException subtype sourced from SAIF.Web.API.Core's exception taxonomy, so callers can catch and branch on strongly-typed error conditions instead of inspecting raw HTTP status codes.

Purpose

• Decide, from an IRestResponse's status code, whether a request succeeded (200–399) or failed (BR-16).
• Extract a human-readable error message: the response body when present; otherwise, a nonstandard fallback in GetContent that does not reliably use RestSharp's ErrorMessage/ErrorException, and only synthesizes a status line when both are absent (BR-17).
• Map the HTTP status code to a specific SAIFException subtype: NoMatchingDataException (404), UnauthorizedAccessException (401/403), InvalidDataException (400), or InternalServerError (all other failure codes) (BR-20).

Context

• Namespace: SAIF.Web.API.Clients
• Assembly/package: SAIF.Web.API.Clients (net35 build variant; not shipped by the current package definition — see Overview)

Public members

Member	Signature	Purpose
EnsureSuccessfulResponse	public static void EnsureSuccessfulResponse(IRestResponse response)	Entry point called by JsonHttpClient; throws a typed SAIFException subtype when the status code is <200 or >=400, otherwise returns normally (BR-16).
ToKnownError	public static void ToKnownError(HttpStatusCode statusCode, string content)	Maps a status code and response body directly to a specific SAIFException subtype and throws it; callable independently of EnsureSuccessfulResponse (BR-18, BR-19, BR-20).

Non-public implementation details

Member	Signature	Purpose
GetContent	private static string GetContent(IRestResponse response)	Non-public helper returning response.Content when nonblank; otherwise string.Empty if only ErrorMessage is nonblank (with ErrorException null), ErrorMessage (blank) if only ErrorException is non-null, ErrorException.Message when both are present, a synthesized "{code} - {StatusDescription}" when both are absent and the status is not 400, and string.Empty otherwise — a defect-like fallback chain rather than a clean precedence order (BR-17).

Behavioral notes

• The full step-by-step error-translation logic is documented in Translate HTTP failure to typed exception.
• Recognized structured-error property names are errormessage, exceptionmessage, message, and usermessage, matched case-insensitively against parsed JSON tokens (BR-18).
• GetContent uses SAIF.Common.Extensions.IsNullOrWhiteSpace from SAIF.Framework.Common to decide whether a candidate message is usable.

Constraints and usage notes

• Error responses are surfaced verbatim: if the remote API returns sensitive detail in an error body, this type propagates it into the exception message without redaction.*
• GetContent's fallback logic when the response body is blank appears to be a defect rather than designed behavior: a lone nonblank ErrorMessage (with no ErrorException) is discarded in favor of string.Empty, and a lone ErrorException (with a blank ErrorMessage) is discarded in favor of the blank ErrorMessage, so ErrorException.Message is only ever surfaced when both fields happen to be set. See BR-17 for the verified branch-by-branch behavior.

Note: Statements marked with * were inferred from code structure, naming conventions, or contextual evidence where direct confirmation was not available in source artifacts.

Sources

• src/SAIF.Web.API.Clients/ExceptionHandler.cs
• src/SAIF.Web.API.Core/SAIFException.cs