CODEWITHSUNDEEP
springspring-bootspring-batch
javakart
javakart

Reputation: 43

How to Read Records From Any Database Table and Export As TextFile Using Spring Batch

I am building a spring batch job that will be invoked through a webservice. The webservice will take a list of select and delete statement pairs. The records returned by the select statement will be saved as a CSV on the filesystem and then those same records will be deleted by executing the supplied delete statement.

I have seen a number of ColumnRowMapper examples but that requires me to create a POJO for each table entity. I am looking for a solution that will handle any column from any table. Any suggestions on approach?

****UPDATE**** Since writing this post, I've landed on the following solution.

@Bean
@StepScope
public JdbcCursorItemReader<Map<String, ?>> getRowsOfDataForExportFromTable(){
    JdbcCursorItemReader<Map<String, ? extends Object>> databaseReader = new JdbcCursorItemReader<>();

    databaseReader.setDataSource(jdbcTemplate.getDataSource());
    databaseReader.setSql("select * from SOME_TABLE where last_updated_date < DATE_SUB(NOW(), INTERVAL 10 DAY);");
    databaseReader.setRowMapper(new RowMapper<Map<String, ? extends Object>>() {
        @Override
        public Map<String, ? extends Object> mapRow(ResultSet resultSet, int i) throws SQLException {
            Map<String,String> resultMap = new LinkedHashMap<>();
            int numOfColumns = resultSet.getMetaData().getColumnCount();
            for (int j = 1; j < numOfColumns+1; j++){
                String columnName = resultSet.getMetaData().getColumnName(j);
                String value = resultSet.getString(j);
                resultMap.put(columnName,value);
            }

            return resultMap;
        }
    });
    return databaseReader;
}

The above ItemReader will build a LinkedHashMap row mapper where the column name is the key and the column value is the value.

Upvotes: 2

Views: 797

Answers (1)

Vadim Beskrovnov
Vadim Beskrovnov

Reputation: 961

Did you try to use Map instead of POJO? You can dynamically fill it in Reader, and then create CSV file from this Map.

Upvotes: 1

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