SQL processor

SQL processors allow you to handle SQL statements that are generated from corresponding SQL templates. To designate a DAO method as an SQL processor, annotate it with @SqlProcessor:

@Dao
public interface EmployeeDao {
    @SqlProcessor
    <R> R process(Integer id, BiFunction<Config, PreparedSql, R> handler);
    ...
}

Warning

It is essential to be aware of SQL injection vulnerabilities when using this feature. Whenever possible, consider using alternatives to SQL processors for better security.

Return type

The return type must be the same type as the third type parameter of BiFunction:

@SqlProcessor
String process(Integer id, BiFunction<Config, PreparedSql, String> handler);

If the return type is void, the third type parameter of BiFunction must be Void:

@SqlProcessor
void process(Integer id, BiFunction<Config, PreparedSql, Void> handler);

Parameter

Include a parameter whose type is BiFunction. The BiFunction parameter accepts a configuration and an SQL statement then processes them. Parameters other than the BiFunction parameter are used in the SQL template.

Example

Suppose you want to change the SQL statement generated from an SQL template and execute it:

EmployeeDao dao = ...
dao.process(1, (config, preparedSql) -> {
  String sql = preparedSql.getRawSql();
  String anotherSql = createAnotherSql(sql);
  DataSource dataSource = config.getDataSource()
  Connection connection = dataSource.getConnection();
  PreparedStatement statement = connection.prepareStatement(anotherSql);
  return statement.execute();
});

select * from employee where id = /*^ id */0