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Patch

procedure Patch(const aURL: string);

Example​

procedure ScriptEvent(var Value: variant);
begin
  Http.ContentAsUTF8 := '{"status":"ready"}';
  Http.Header['Content-Type'] := 'application/merge-patch+json';
  Http.Header['If-Match'] := '"example-version"';
  Http.Patch('https://api.example.invalid/resources/example-123');
  Value := Http.Response.ResponseCode;
end;

Usage​

Sends a synchronous PATCH request with the complete nonempty pending body and captures the response through the shared HTTP pipeline.

Additional Technical Info​

Patch selects hmPatch, stores aURL, and synchronously invokes Indy's PATCH overload. If the pending Content size is positive, Indy sends the complete stream from position zero; otherwise Velox passes no source stream.

Velox does not select a patch document format, set Content-Type, add If-Match, determine whether the server supports PATCH or verify that the modification was applied. Those are endpoint-contract responsibilities. Use the exact media type and precondition expected by the service; PATCH is not inherently idempotent.

The pending body is normally cleared in finally, including after operational request failures, and must be loaded again for a retry. An authentication preflight failure can exit before that finaliser and preserve it. Response content is captured and rewound after completion.

HTTP 4xx/5xx statuses normally remain inspectable through Response. Network/TLS/proxy/stream errors can raise. Retrying after an ambiguous failure can apply the patch twice; require an idempotency/precondition design before doing so.

The call blocks, inherits persistent headers/cookies/authentication, accepts unrestricted destinations, and uses the current non-validating local SSL configuration.

External references

Created 2026-07-15