Customize PreparedStatementCreatorFactory in getPreparedStatementCreator [SPR-16050]

[spring-projects-issues]

diego lovison opened SPR-16050 and commented

I would like to create a streamable query using spring jdbc.

public class StreamNamedParameterJdbcTemplate extends NamedParameterJdbcTemplate {

    private final DataSource dataSource;

    public StreamNamedParameterJdbcTemplate(DataSource dataSource) {
        super(dataSource);

        this.dataSource = dataSource;
    }

    @SneakyThrows(SQLException.class)
    public <T> Stream<T> streamQuery(String sql, Map<String, Object> parameters, RowMapper<T> rowMapper) {

        Connection connection = DataSourceUtils.getConnection(dataSource);

        PreparedStatementCreator preparedStatementCreator =
                this.getPreparedStatementCreator(sql, new MapSqlParameterSource(parameters));

        PreparedStatement preparedStatement = preparedStatementCreator.createPreparedStatement(connection);

        StreamableQuery<T> streamableQuery =
                new StreamableQuery<>(connection, dataSource, preparedStatement, rowMapper);

        return streamableQuery.stream();
    }
}

My method is delegating a call to getPreparedStatementCreator in the class NamedParameterJdbcTemplate to avoid copying and pasting the following code:

protected PreparedStatementCreator getPreparedStatementCreator(String sql, SqlParameterSource paramSource) {
     ParsedSql parsedSql = getParsedSql(sql);
     String sqlToUse = NamedParameterUtils.substituteNamedParameters(parsedSql, paramSource);
     Object[] params = NamedParameterUtils.buildValueArray(parsedSql, paramSource, null);
     List<SqlParameter> declaredParameters = NamedParameterUtils.buildSqlParameterList(parsedSql, paramSource);
     PreparedStatementCreatorFactory pscf = new PreparedStatementCreatorFactory(sqlToUse, declaredParameters);
     return pscf.newPreparedStatementCreator(params);
}

My project is using DB2 and I need to change the resultSetType parameter value in the class PreparedStatementCreatorFactory.

Today I can only do that copying and past the entire method.

The idea about stream query come from: https://github.com/APNIC-net/spring-jdbctemplate-streams

---

Issue Links:

• Add iterable JDBC template to process large amount of data [SPR-13900] #18474 Add iterable JDBC template to process large amount of data
• Add Optional Support to JdbcTemplate [SPR-12662] #17262 Add Optional Support to JdbcTemplate
• Creating a SimpleJdbcInsert from a NamedParameterJdbcTemplate [SPR-16241] #20788 Creating a SimpleJdbcInsert from a NamedParameterJdbcTemplate

[spring-projects-issues]

Juergen Hoeller commented

I've extracted a common getPreparedStatementCreator variant with an optional Consumer<PreparedStatementCreatorFactory> argument. We're using that internally not only from the query but also from the update operations now where we need to customize the generated key handling via PreparedStatementCreatorFactory. In custom operations like yours, you may call that same getPreparedStatementCreator variant with a customizer lambda expression that adapts the result set type.