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ContentType

property ContentType: string read write;

Example​

procedure ScriptEvent(var Value: variant);
begin
  if Response <> nil then
  begin
    Response.ContentType := 'application/json; charset=utf-8';
    Response.ContentString := '{"value":42}';
    Value := Response.ContentType;
  end;
end;

Usage​

ContentType gets or sets the response media type while Velox extracts and retains its charset separately for text encoding.

Additional Technical Info​

ContentType supplies the media type and optional parameters for the response. The bridge passes the value to Indy and also caches the original assigned string. A subsequent script read therefore normally returns the original spelling/parameters, while Indy has separately removed the charset parameter into its CharSet field for encoding and wire-header reconstruction.

Important state behavior follows from that split:

  • assigning a value with charset=... changes Indy's encoding charset;
  • assigning another nonempty value without a charset does not necessarily clear the previous charset;
  • when no charset has ever been set, Indy applies legacy defaults for text/* (ISO-8859-1, or US-ASCII for XML text types); and
  • assigning the empty string clears the media type and charset together.

To change from text to binary safely after a previous charset, clear the property first and then set the binary type. Otherwise an old charset can be reattached to a later application/octet-stream or image response. For response text, specify the intended charset explicitly before assigning ContentString.

If body text/stream exists and the underlying media type is still empty, current automatic sending sets text/html; charset=UTF-8. This fallback does not inspect the bytes and can mislabel JSON, XML, files or binary content. Set the correct registered media type deliberately.

The property does not convert a stream, validate that content matches the declared type, perform content negotiation or apply ContentEncoding. Treat user-supplied type text as untrusted; do not allow control characters or arbitrary response-header injection. Test Response for nil.

External references

Created 2026-07-15