tursodatabase/turso · error · SQLException

Cannot convert to ASCII stream: {type}

Error message

Cannot convert to ASCII stream: {type}

What it means

getAsciiStream(int) returns a ByteArrayInputStream for exactly two runtime shapes: String columns (encoded US-ASCII) and byte[]/BLOB columns. Any other type (Long, Double, the 8-byte date blob, ...) throws with the class name — the driver performs no toString() coercion for streams.

Source

Thrown at bindings/java/src/main/java/tech/turso/jdbc4/JDBC4ResultSet.java:249

        });
  }

  @Override
  @SkipNullableCheck
  public InputStream getAsciiStream(int columnIndex) throws SQLException {
    final Object result = resultSet.get(columnIndex);
    wasNull = result == null;
    if (result == null) {
      return null;
    }
    return wrapTypeConversion(
        () -> {
          if (result instanceof String) {
            return new ByteArrayInputStream(((String) result).getBytes("US-ASCII"));
          } else if (result instanceof byte[]) {
            return new ByteArrayInputStream((byte[]) result);
          }
          throw new SQLException("Cannot convert to ASCII stream: " + result.getClass());
        });
  }

  @Override
  @SkipNullableCheck
  public InputStream getUnicodeStream(int columnIndex) throws SQLException {
    final Object result = resultSet.get(columnIndex);
    wasNull = result == null;
    if (result == null) {
      return null;
    }
    return wrapTypeConversion(
        () -> {
          if (result instanceof String) {
            return new ByteArrayInputStream(((String) result).getBytes("UTF-8"));
          } else if (result instanceof byte[]) {
            return new ByteArrayInputStream((byte[]) result);
          }

View on GitHub (pinned to bad083fafb)

Solutions

1. Fall back to text yourself: new ByteArrayInputStream(rs.getString(i).getBytes(StandardCharsets.US_ASCII)) for non-text columns.
2. CAST in SQL: SELECT CAST(col AS TEXT) ... so the value arrives as a String.
3. Branch on ResultSetMetaData.getColumnType() and only call stream getters for CHAR/VARCHAR/TEXT/BINARY columns.

Example fix

// before
InputStream is = rs.getAsciiStream(1); // INTEGER column -> throws

// after
InputStream is = new ByteArrayInputStream(
    rs.getString(1).getBytes(StandardCharsets.US_ASCII));

Object v = rs.getObject(1);
InputStream is = (v instanceof String s)
    ? new ByteArrayInputStream(s.getBytes(StandardCharsets.US_ASCII))
    : rs.getAsciiStream(1); // safe only for String/byte[] columns

static boolean isAsciiStreamable(Object v) {
    return v instanceof String || v instanceof byte[];
}

try {
    return rs.getAsciiStream(i);
} catch (SQLException e) {
    if (e.getMessage() != null && e.getMessage().contains("Cannot convert to ASCII stream")) {
        return new ByteArrayInputStream(
            rs.getString(i).getBytes(StandardCharsets.US_ASCII));
    }
    throw e;
}

When it happens

Trigger: rs.getAsciiStream() on INTEGER/REAL columns; on expressions like COUNT(*); on the driver's 8-byte date/time blobs; generic exporters that stream every column of every row.

Common situations: Row-to-CSV export utilities; numeric aggregates expected to stream as text; schema drift turning a formerly TEXT column numeric via SQLite type affinity.

Related errors

• Cannot convert value to Date: {type}
• Cannot convert value to Timestamp: {type}
• Cannot convert to Unicode stream: {type}
• Cannot convert to binary stream: {type}
• Unsupported object type in setObject: {type}

AI-assisted analysis of tursodatabase/turso@bad083fafb (2026-08-16). Data as JSON: /api/errors/b5fb1d6da03a6831. Report an issue: GitHub.