Over time the number of koans has grown to be large. Some of them examine various edge cases of the framework or special usage scenarios. If you want to be focus on just the "core" to learn the basics of MyBatis, I recommend doing koans 1-12, 15-18 and 21.
Configuration Koan
Learn:
- how to configure a MyBatis config file, including a shared properties that will used by the MyBatis config file
- how to wire up your Java code to use the MyBatis config file
- how to create a SqlSessionFactory
Xml mapper file
Learn:
- how to reference a mapper file from a MyBatis config file
- how to set up a SQL mapping in a mapper file
- how to create a
SqlSession - how to call the SQL mapping and get data from the database via MyBatis
- the basic types of datastructures that MyBatis can return and how to specify them
Domain objects
Learn:
- how to create a mapper xml file that returns a domain object, rather than a generic data structure
- how to return a list or map of domain objects from a mapped SQL query
- how to set up a TypeAlias in the MyBatis config file
Domain objects, using underscore to camelCase mapping
Learn:
- how to tell MyBatis to convert underscores to camelCase to auto-map database column names to object property names
Mapper interface
Learn:
- how to create and use a Java Mapper interface to do the same type of queries in the previous koans
Multiple Arguments and RowBounds
Learn:
- how to create and use a Java Mapper interface to do the same type of queries in the previous koans
- how to return a simple numeric value from a mapped SQL query
- how to pass in multiple arguments to a mapped query (including using annotations)
- how to use a MyBatis RowBounds object to limit the number of results returned
Annotation driven mappings
Learn:
- how to do annotation driven mappings
- how to specify a mapper in the config file when you don't have an XML mapping file
Updates, inserts and deletes
Learn:
- how to do updates, inserts and deletes
- in xml mapping files
- annotation driven in Java Mapper interfaces
- how to use the
selectKeyfeature of MyBatis to dynamically create a new key for a domain object being inserted into the database - the effect of calling
rollback,commitor neither on the session object when executing DML statements via MyBatis
<sql> and dynamic string substitution
Learn:
- how to use the
<sql>MyBatis element to keep your SQL DRY ("don't repeat yourself") - how to do dynamic string substitution in sections of SQL that are not bound variables to PreparedStatements
ResultMaps, part 1
Learn:
- how to use a ResultMap for a single table query
- how to use a ResultMap for a multiple table query, using the "association" feature
- how to use ResultMaps as part of a "nested select" (the N+1 approach)
ResultMaps, part 2
Learn:
- how to use a ResultMap for a multiple table query, using the "collection" feature
TypeHandlers
Learn:
- How to use a MyBatis TypeHandler in order to set a domain specific object type as a field in a mapped object
- Learn to set a TypeHandler for all object type (for any query that uses it)
- Learn to set a TypeHandler for a specify field/column of a specify mapped query
MyBatis and Immutable Objects, part 1
Learn:
- How to use a MyBatis with immutable objects that have no setter fields
- Learn to set a TypeHandler for all object type (for any query that uses it)
- Learn to set a TypeHandler for a specify field/column of a specify mapped query
- How to use multiple mapper files that reference each other
MyBatis and Immutable Objects, part 2
Learn:
- How to use a MyBatis with immutable objects that have no setter fields and without having to directly map to long constructor param lists by implementing MyBatis' ObjectFactory
- How to use a ResultHandler to do additional things with the objects created by MyBatis (or your ObjectFactory), such as filtering what results are returned
Database inserts, revisited
Learn:
- How to use a TypeHandler to insert into a table where its mapped domain object depends on other domain objects
- How to insert null values into a nullable columns in the database
Calling stored procedures via XML mappings
Learn:
- How to call a stored procedure and stored functions from MyBatis using XML mapping
- How to handle both IN and OUT parameter types
Calling stored procedures via Java annotation mappings
Learn:
- How to call a stored procedure and stored functions from MyBatis using Java annotations
Statement Builders
Learn:
- How to use the MyBatis SelectBuilder "DSL" to generate SQL statements
- How to use the MyBatis SqlBuilder "DSL" to generate SQL insert, update and delete statements
- How to use the MyBatis SqlBuilder "DSL" to generate compound SQL (subselects)
[Update]: In mybatis-3.2, SQLBuilder has been deprecated, so Koan18 is now vestigial. However, I will leave it in for a while longer in case people are still using older versions and depending on SQLBuilder. You should stop using it. See the MyBatis documentation for more details.
Using the Null object pattern with MyBatis
Learn:
- How to create a Null object when a null value is returned from a database query
Prepared vs. non-prepared statements in MyBatis
Learn:
- The difference between the #{} variable notation and ${}
- How to use the ${} notation with a domain object
- How to deal with an enum type in your sakila database (if using PostgreSQL or MySQL)
Dynamic SQL
Learn:
- How to use the
<if>conditional to build a SQL statement - How to most effectively build a compound where and set clause using the
<where>and<set>features - How to loop over lists when building SQL using
<foreach>
(Slightly) More Complicated Mappings
Learn:
- How to do an insert that takes two domain objects and extract the appropriate ids from them in the MyBatis mapping
- How to map a three table join
Using Java Enums with MyBatis
Learn:
- How to map a Java Enum to the result of a database query
- How to map a Java Enum to a database DML (insert/update/delete)
Get MyBatis to return non-default Collection Types
Learn:
- How to have MyBatis return a CopyOnWriteArrayList instead of an ArrayList from a query
- How to have a case-insensitive Map returned instead of a regular HashMap from a query
Map/shoehorn multiple database columns into one Java field
Learn:
- How to take a query like
select foo1, foo2, foo3and create a domain object that has an foo array, rather than three separate fields, one for each foo.
Return Maps from MyBatis where the key is the id (primary key) and the value is either a domain object or a particular string from the table you are querying from
Learn:
- How to return
Map<Integer,DomainObject>instead ofList<Map<String,Object>> - How to return
Map<Integer,String>instead ofList<Map<String,Object>>from a query like:select id, fooand the map is a mapping of id to foo values.