Revanate, a Java based ORM library simplifying connection to the PostgreSQL without the need for SQL or connection managment.
- PostgreSQL - version 42.3.3
- Java - version 8.0
- Apache commons - version 2.9.0
- JUnit - version 4.13.2
- Connection pooling
- Transaction managment
- CRUD operations
- Tables are created with correct foreign keys
Using git:
- Start in a directory where to want to clone this repository
- Execute
git clone https://github.com/ykoziy/revanate_p1.git - Switch into newly created directory
revanate_p1 - In console do
mvn install - Add this as dependency in another maven project (pom.xml)
<groupId>com.revanate</groupId>
<artifactId>revanate_p1</artifactId>
<version>0.0.1-SNAPSHOT</version>
In order for the Revanate ORM to know which Java classes need to be mapped with the database tables, you must properly annotate your Model layer classes.
@Entity(tableName = "table_name")- defines a Java class as entity to be mapped.@Column(columnName = "column_name")- defines a field inside a class as a column, will be mapped to the DB table.@ForeignKey(columnName = "column_name")- defines foreign key column, sets foreign key column name@Id(columnName = "column_name", autoIndex = "auto")- defines primary key column, autoIndex set toautowill auto incerement primary key
In order to build a session you must configure ORM, build a SessionManager and open a session.
Configuration is store in the project resources folder as an XML file with extension *.cfg.xml. Example configuration file, configuration is limited for time being. All options are in this example.
<revanate-configuration>
<!-- These are JDBC Connection Credentials -->
<property name="revanate.connection.url">jdbc:postgresql://localhost:5432/postgres?currentSchema=hibernate</property>
<property name="revanate.connection.username">postgres</property>
<property name="revanate.connection.password">postgres</property>
<!-- List of mapping files -->
<mapping class="com.revanate.testrun.model.Crime" />
<mapping class="com.revanate.testrun.model.SuperVillain" />
<mapping class="com.revanate.testrun.model.SuperPrison" />
</revanate-configuration>
Once you have a valid configuration file, you can get a SessionManager.
SessionManager sm = new Configuration().configure("revanate.cfg.xml").buildSessionManager();
Using SessionManager you can now open a session. Opening a session establishes a connection to the PostgreSQL database. Almost all operations are performed on Session object.
To begin a transaction just use:
Transaction tx = ses.beginTransaction();
Subsequent transaction control done via Transaction class.
public Session openSession() - use it to start the Session, returns Session
List<EntityModel<Class<?>>> getEntityList() - gets EntityModel list.
void delete(Object object) - delete object from the table row.
Object save(Object object) - store object in database table, returns primary key.
void update(Object object) - update object in database table.
<T> Object get(Class<?> entityClass, T id) - get object from the database, by using primary key id
Query getAll(Class<?> resultType) - get all objects from the database. Returns Query.
Transaction beginTransaction() - begins transaction, returns Transaction.
void close() - close the session. Releases connection and returns in to connection pool, clean up other resources.
Used for SQL transactions. Savepoints are stored as a HashMap.
void commit() - commit transaction.
void releaseSavepoint(String name) - removes the specified Savepoint.
void rollback() - undo all changes for the current transaction.
void rollback(String name) - undo all the changes after the given savepoint.
void setAutoCommit(boolean isEnabled) - changes auto commit mode for the current connection.
void setSavepoint(String name) - set savepoint with specified name.
Configuration addEntittyModel(Class<?> annotetedClass) - manually add entity model to the list of EntityModels
SessionManager buildSessionManager()- builds SessionManager
Configuration configure(String resource) - do configuration from XML
String getDbPassword() - get DB password
String getDbUrl() - get DB URL
String getDbUsername() - get DB username
List<EntityModel<Class<?>>> getEntityModelList() - get EntityModel list
Configuration setConnection(String dbUrl, String dbUsername, String dbPassword) - set connection to specified parameters
void setDbPassword(String dbPassword) - set password
void setDbUrl(String dbUrl) - set dbUrl
void setDbUsername(String dbUsername) - set DB username
void setEntityModelList(List<EntityModel<Class<?>>> entityModelList) - set EntityModel list to specified list