Reduce your boiler-plate code with SimpleFlatMapper

About me

No time for that sh*t, it's lightning talk!

Scuse me French.

@arnaudroger http://simpleflatmapper.org

SimpleFlatMapper

What ?

Maps flat structure

CSV
Jdbc ResultSet
HSSFSheet
jOOQ Record
Datastax ResultSet
...

To POJOs with no configuration needed,

and no use of Unsafe and setAccessible.

No boxing either, no external dependencies.

@arnaudroger http://simpleflatmapper.org

SimpleFlatMapper

Inject via:

Constructor
Setter, everybody can do that.
Field if public and non final.
Factory method
Builders
Value type
Inner Object

@arnaudroger http://simpleflatmapper.org

SimpleFlatMapper

But is it fast?

Yes super fast,

generate bytecode using ASM*
no boxing
JIT can inline the cr*p out of it

* Unfortunatly due to the complexity of OSGI ClassLoader lifecycle ASM generation is disable when running in an OSGI container

PS : reflection call is not slow, lookup is.

@arnaudroger http://simpleflatmapper.org

SimpleFlatMapper

Less bullsh*t more code

let's look at JdbcTemplate example here.

@arnaudroger http://simpleflatmapper.org

The schema

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The data

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The data

So that query

Returns

@arnaudroger http://simpleflatmapper.org

Simple select

SELECT firstname, lastname
FROM users
Manual RowMapper

RowMapper<User> rm = 
    (rs, i) -> new User(
                  rs.getString("firstname"),   
                  rs.getString("lastname"));

So far so good,

but only work when those 2 columns are present.

@arnaudroger http://simpleflatmapper.org

Simple select

Why not use BeanPropertyRowMapper?

as per javadoc

Please note that this class is designed to provide convenience rather than high performance. For best performance, consider using a custom RowMapper implementation.

It is the slowest mapper on the planet... don't use it.

@arnaudroger http://simpleflatmapper.org

Simple select - SFM

SFM RowMapper

  RowMapper<User> rm =
    JdbcTemplateMapperFactory
        .newInstance()
        .newRowMapper(User.class);

adaptive, will map any column from the rs
faster because it uses index lookup

Not convinced? I get you... next lets look at ....

<dependency>
    <groupId>org.simpleflatmapper</groupId>
    <artifactId>sfm-springjdbc</artifactId>
    <version>3.11.8</version>
</dependency>

@arnaudroger http://simpleflatmapper.org

one-to-many?

Not possible with RowMapper.
Need ResultSetExtractor + RowMapper

@arnaudroger http://simpleflatmapper.org

one-to-many?

ResultSetExtractor + RowMapper

RowMapper<User> userRowMapper =
        (rs, i) ->
                new User(
                        rs.getInt("id"),
                        rs.getString("firstname"),
                        rs.getString("lastname"));

ResultSetExtractor<List<User>> rse = rs -> {
    List<User> users = new ArrayList<>();
    User currentUser = null;
    while (rs.next()) {
        int id = rs.getInt("id");
        if (currentUser == null) { // initial object
            currentUser = userRowMapper.mapRow(rs, 0);
        } else if (currentUser.getId() != id) { // break
            users.add(currentUser);
            currentUser = userRowMapper.mapRow(rs, 0);
        }
        currentUser.getRoles().add(rs.getString("roles_name"));
    }
    if (currentUser != null) { // last object
        users.add(currentUser);
    }
    return users;
};

@arnaudroger http://simpleflatmapper.org

one-to-many?

With SFM

ResultSetExtractor<List<User>> rse = 
        JdbcTemplateMapperFactory
                .newInstance()
                .addKeys("id")
                .newResultSetExtractor(User.class);

Is that it?

can I have more joins?

see https://arnaudroger.github.io/blog/2017/03/02/jooq-one-to-many-without-dto.html

with example of mapping to

Tuple2<AuthorRecord,List<Tuple2<BookRecord,List<BookToBookStoreRecord>>>

@arnaudroger http://simpleflatmapper.org

Crud operation you ask?

JdbcTemplateCrud<User, Long> objectCrud =
      JdbcTemplateMapperFactory.newInstance()
            .crud(User.class, Integer.class)
            .to(template, "users");

I can Create

objectCrud.create(user);

Read

objectCrud.read(2)

Update

objectCrud.update(user);

Delete

objectCrud.delete(2);

I have also batch insert - and upsert for postgres/mysql -

objectCrud.create(Arrays.asList(user1, user2));

objectCrud.createOrUpdate(Arrays.asList(user1, user2));

@arnaudroger http://simpleflatmapper.org

Fastest csv parser

Really ? are you using opencsv? supercsv drop that. the only ones worth considering are

jackson-csv
univocity - only for big file
sfm-csv

@arnaudroger http://simpleflatmapper.org

Fastest csv parser

Benchmark time to parse a 3+ million rows csv

see http://simpleflatmapper.org/12-csv-performance.html

@arnaudroger http://simpleflatmapper.org

Mapping from a csv?

easy as that

try (Iterator<User> it = 
        CsvParser.mapTo(User.class).addKey("id").iterator(myFile)) {
   while(it.hasNext()) {
      User u = it.next();
   }
}