apache/seatunnel · error · FileConnectorException

UNSUPPORTED_DATA_TYPE

UNSUPPORTED_DATA_TYPE

Error message

SeaTunnel format not support this data type " + fieldType.getSqlType()

What it means

XmlWriter.convertToXmlString maps each SeaTunnel field's SqlType to an XML-serializable string; supported types fall through to a default branch that throws FileConnectorException with UNSUPPORTED_DATA_TYPE: 'SeaTunnel format not support this data type <SqlType>'. Types not explicitly handled (certain complex/nested or exotic types beyond MAP/ARRAY/bytes handling) cannot be rendered into XML text.

Source

Thrown at seatunnel-connectors-v2/connector-file/connector-file-base/src/main/java/org/apache/seatunnel/connectors/seatunnel/file/sink/util/XmlWriter.java:128

                return fieldValue.toString();
            case NULL:
                return "";
            case ROW:
                Object[] fields = ((SeaTunnelRow) fieldValue).getFields();
                String[] strings = new String[fields.length];
                for (int i = 0; i < fields.length; i++) {
                    strings[i] =
                            convertToXmlString(
                                    fields[i], ((SeaTunnelRowType) fieldType).getFieldType(i));
                }
                return String.join(fieldDelimiter, strings);
            case MAP:
            case ARRAY:
                return JsonUtils.toJsonString(fieldValue);
            case BYTES:
                return new String((byte[]) fieldValue, StandardCharsets.UTF_8);
            default:
                throw new FileConnectorException(
                        CommonErrorCodeDeprecated.UNSUPPORTED_DATA_TYPE,
                        "SeaTunnel format not support this data type " + fieldType.getSqlType());
        }
    }

    public void flushAndCloseXmlWriter(OutputStream output) throws IOException {
        XMLWriter xmlWriter = new XMLWriter(output, format);
        xmlWriter.write(document);
        xmlWriter.close();
    }

    private void setXmlOutputFormat() {
        this.format = OutputFormat.createPrettyPrint();
        this.format.setNewlines(true);
        this.format.setNewLineAfterDeclaration(true);
        this.format.setSuppressDeclaration(false);
        this.format.setExpandEmptyElements(false);
        this.format.setIndent("\t");

View on GitHub (pinned to cf67b549a7)

Solutions

Flatten or remove unsupported nested fields before the sink (e.g. JSON transform to stringify, or select only scalar columns).
Switch file_format_type to json/parquet, which support nested types.
Serialize the complex field to a string yourself in a transform so it arrives as a supported scalar type.

Example fix

// before
Transform {
  SQL { source_table_name = "t" query = "SELECT nested_col FROM t" }
}
// after
Transform {
  SQL { source_table_name = "t" query = "SELECT CAST(nested_col AS STRING) AS nested_col FROM t" }
}

Defensive patterns

Strategy: type-guard

Validate before calling

// check schema before selecting xml output
for (SeaTunnelDataType<?> t : rowType.getFieldTypes()) {
  if (t.getSqlType() == SqlType.ROW || t.getSqlType() == SqlType.STRUCT) {
    throw new IllegalArgumentException("xml sink does not support nested type " + t);
  }
}

Type guard

boolean isXmlSupported(SeaTunnelDataType<?> t) {
  switch (t.getSqlType()) {
    case STRING: case INT: case BIGINT: case DOUBLE: case BOOLEAN:
    case DATE: case TIMESTAMP: case DECIMAL: case MAP: case ARRAY: case BYTES:
      return true;
    default:
      return false;
  }
}

Try / catch

try {
  xmlWriter.writeData(row);
} catch (FileConnectorException e) {
  if (e.getCode() == CommonErrorCodeDeprecated.UNSUPPORTED_DATA_TYPE) {
    // flatten/stringify the offending column and rewrite
  }
  throw e;
}

Prevention

Prefer json/parquet when schemas contain nested ROW types.
Flatten nested structs in transforms before XML sinks.
Keep an allowlist of supported SqlTypes per file format in your config validation.

When it happens

Trigger: Writing a row to an XML file sink whose schema includes a SeaTunnel type not covered by convertToXmlString's switch (e.g. ROW/nested struct or other unsupported SqlTypes).

Common situations: Sinks downstream of nested transforms producing ROW columns; users adding new SeaTunnel types upstream without checking XML writer support; JSON-flavored nested data routed to XML output.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/c08ccb33d175ba38. Report an issue: GitHub.