Using hashmap as resultType in MyBatis

If you have an SQL statement like the following, which you don't necessarily need to retrieve into a Java Bean, you can use MyBatis' resultType="hashmap" attribute on your select statement.

The MyBatis documentation says the following:

"Such a statement simply results in all columns being automatically mapped to the keys of a HashMap, as specified by the resultType attribute."

What this actually means is for each row that is returned by your SQL statement, a HashMap will be created which will store the column name and the associated value of the field.

To illustrate

If you have the following table called cars

car_id	car_make	car_model	car_color
22	Nissan	Altima	Blue
40	Jaguar	X6	Green
61	BMW	328i	Black
81	Audi	R8	Silver

And your mapper file contain this SQL statement:

<select id="selectCars" resultType="hashmap">
 select car_id, car_model, car_color
 from cars 
 order by car_id
</sql>

When you run the following code:

ArrayList<HashMap<String,Object>> results = (ArrayList<HashMap<String,Object>>)session.selectList("com.yourproject.package.TestMappers.sqlStatementX");

/**
loop through each row returned
each key will be the column_name
each value will be the field value for that row and column
*/
for(HashMap<String,Object> row : results){

    log.info("car id: " + row.get("car_id"));
    log.info("car model: " + row.get("car_model"));
    log.info("car color: " + row.get("car_color"));

}

You would get following output

22	Altima	Blue
40	X6	Green
61	328i	Black
81	R8	Silver