ResultSet wasNull throws exception on insert row

[mrotteveel]

As reported on firebird-java - Error: No row available for wasNull., the method wasNull throws an exception when on the insert row.

This can be reproduced with the program provided by Pierre Vacher:

    public void testWasNull(java.sql.Connection connection) {
        String select = "select * from t1";
        try {
            populateTable(connection);

            java.sql.PreparedStatement ps = connection.prepareStatement(select,
                                                                        java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE,
                                                                        java.sql.ResultSet.CONCUR_UPDATABLE);

            java.sql.ResultSet rs = ps.executeQuery();

            rs.moveToInsertRow();
            rs.updateNull(1);
            rs.updateString(2, "s10");

            for (int i = 1; i <= rs.getMetaData().getColumnCount(); i++) {
                Object value = rs.getObject(i);
                if (rs.wasNull()) {
                    System.out.println("SensitiveResultSet.testWasNull() Value was Null");
                }
                else {
                    System.out.println("SensitiveResultSet.testWasNull() Value: " + value.toString());
                }
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    void populateTable(java.sql.Connection connection) throws SQLException {
        java.sql.Statement statement = connection.createStatement();
        //statement.execute("drop table t1 if exists");
        statement.execute("create table t1 (i int primary key, v varchar(10))");
        statement.close();

        String insert = "insert into t1 values(?, ?)";
        java.sql.PreparedStatement ps = connection.prepareStatement(insert);

        for (int i = 0; i < 10; i++) {
            ps.setInt(1, i);
            ps.setString(2, String.valueOf(i) + " s");
            ps.execute();
        }

        ps.close();
    }

producing the exception:

java.sql.SQLException: No row available for wasNull.
        at org.firebirdsql.jdbc.FBResultSet.wasNull(FBResultSet.java:465)
        at io.github.prrvchr.jdbcdriver.resultset.SensitiveResultSet.testWasNull(SensitiveResultSet.java:117)
        at io.github.prrvchr.jdbcdriver.resultset.SensitiveResultSet.<init>(SensitiveResultSet.java:96)
        at io.github.prrvchr.jdbcdriver.resultset.ResultSetHelper.getResultSet(ResultSetHelper.java:77)
        at io.github.prrvchr.uno.sdbcx.RowSetSuper.<init>(RowSetSuper.java:69)
        at io.github.prrvchr.uno.sdb.RowSet.<init>(RowSet.java:58)
        at io.github.prrvchr.uno.sdb.PreparedStatement.getResultSet(PreparedStatement.java:93)
        at io.github.prrvchr.uno.sdbc.PreparedStatementMain.executeQuery(PreparedStatementMain.java:404)

[mrotteveel]

The javadoc for wasNull() doesn't mention any requirement to throw an exception if not currently in a row:

Reports whether the last column read had a value of SQL NULL. Note that you must first call one of the getter methods on a column to try to read its value and then call the method wasNull to see if the value read was SQL NULL.

Returns:
true if the last column value read was SQL NULL and false otherwise
Throws:
SQLException - if a database access error occurs or this method is called on a closed result set

So possibly just dropping that check is the simplest and correct fix.

[mrotteveel]

To be frontported to Jaybird 6 as well.

[prrvchr]

Thanks for this fix and the archives made available.