One2ManyExample

Introduction

This demonstrates one to many relationship capability of the library using 2 types of different child objects.

Details

Parent class

@TableInfo(tableName = "parent_entity")
public class One2ManyParentEntity extends DefaultEntity
{
    @ColumnInfo(columnType = ColumnType.INTEGER,key = true)
    private int id;
    @ColumnInfo(columnType = ColumnType.VARCHAR)
    private String name;
    @ForeignKeyInfoList(infoList = {
        @ForeignKeyInfo(name = "parent2childA",
                relatedObjectType = One2ManyChildEntityA.class,
                updateRule = ReferentialRuleType.RESTRICT,
                deleteRule = ReferentialRuleType.CASCADE,
                fieldMappings =  {@ForeignKeyFieldMapping(fromField = "id",toField = "parentId")})
        ,
        @ForeignKeyInfo(name = "parent2childB",
                relatedObjectType = One2ManyChildEntityB.class,
                updateRule = ReferentialRuleType.RESTRICT,
                deleteRule = ReferentialRuleType.CASCADE,
                fieldMappings =  {@ForeignKeyFieldMapping(fromField = "id",toField = "parentId")})
    })
    private Collection<One2ManyChildEntity> childEntities;

    public One2ManyParentEntity()
    {
        childEntities = new ArrayList<One2ManyChildEntity>();
    }

    public int getId()
    {
        return id;
    }

    public void setId(int id)
    {
        this.id = id;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public Collection<One2ManyChildEntity> getChildEntities()
    {
        return childEntities;
    }

    public void setChildEntities(Collection<One2ManyChildEntity> childEntities)
    {
        this.childEntities = childEntities;
    }
}

Child Base Class

public abstract class One2ManyChildEntity extends DefaultEntity
{
    public abstract String getName();

    public abstract void setName(String name);
}

Child Sub Class 1

@TableInfo(tableName = "child_entity_a")
public class One2ManyChildEntityA extends One2ManyChildEntity
{
    @ColumnInfo(columnType = ColumnType.INTEGER,key = true)
    private int parentId;
    @ColumnInfo(columnType = ColumnType.INTEGER,key = true)
    private int indexNo;
    @ColumnInfo(columnType = ColumnType.VARCHAR)
    private String name;


    public int getParentId()
    {
        return parentId;
    }

    public void setParentId(int parentId)
    {
        this.parentId = parentId;
    }

    public int getIndexNo()
    {
        return indexNo;
    }

    public void setIndexNo(int indexNo)
    {
        this.indexNo = indexNo;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }
}

Child Sub Class 2

@TableInfo(tableName = "child_entity_b")
public class One2ManyChildEntityB extends One2ManyChildEntity
{
    @ColumnInfo(columnType = ColumnType.INTEGER,key = true)
    private int parentId;
    @ColumnInfo(columnType = ColumnType.INTEGER,key = true)
    private int indexNo;
    @ColumnInfo(columnType = ColumnType.VARCHAR)
    private String name;


    public int getParentId()
    {
        return parentId;
    }

    public void setParentId(int parentId)
    {
        this.parentId = parentId;
    }

    public int getIndexNo()
    {
        return indexNo;
    }

    public void setIndexNo(int indexNo)
    {
        this.indexNo = indexNo;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }
}

Testing Class

get the source for ExampleBase from https://github.com/Adipa-G/dbgate/wiki/SimpleEntityExample

public class One2ManyExample extends ExampleBase
{
    private static int id = 43;

    public One2ManyExample()
    {
        dbName = "one_2_many_example";
    }

    public One2ManyParentEntity createEntityWithChildern()
    {
        One2ManyParentEntity entity = new One2ManyParentEntity();
        entity.setId(id);
        entity.setName("Parent");

        One2ManyChildEntityA childEntityA = new One2ManyChildEntityA();
        childEntityA.setName("Child A");
        entity.getChildEntities().add(childEntityA);

        One2ManyChildEntityB childEntityB = new One2ManyChildEntityB();
        childEntityB.setName("Child B");
        entity.getChildEntities().add(childEntityB);

        return entity;
    }

    public void patch() throws DBPatchingException, SQLException
            ,TransactionCreationFailedException,TransactionCommitFailedException
    {
        ITransaction tx = factory.createTransaction();
        Collection<Class> entityTypes = new ArrayList<Class>();
        entityTypes.add(One2ManyParentEntity.class);
        entityTypes.add(One2ManyChildEntityA.class);
        entityTypes.add(One2ManyChildEntityB.class);
        factory.getDbGate().patchDataBase(tx, entityTypes, false);
        tx.commit();
        DBMgtUtility.close(tx);
    }

    public void persist() throws PersistException, SQLException
            ,TransactionCreationFailedException,TransactionCommitFailedException
    {
        ITransaction tx = factory.createTransaction();
        One2ManyParentEntity entity = createEntityWithChildern();
        entity.persist(tx);
        tx.commit();
        DBMgtUtility.close(tx);
    }

    public One2ManyParentEntity retrieve(int id) throws SQLException,RetrievalException
            ,TransactionCreationFailedException
    {
        ITransaction tx = factory.createTransaction();
        PreparedStatement ps = tx.getConnection().prepareStatement("select * from parent_entity where id = ?");
        ps.setInt(1, id);
        ResultSet rs = ps.executeQuery();
        One2ManyParentEntity entity = null;
        if (rs.next())
        {
            entity = new One2ManyParentEntity();
            entity.retrieve(rs,tx);
        }
        DBMgtUtility.close(rs);
        DBMgtUtility.close(ps);
        DBMgtUtility.close(tx);
        return entity;
    }

    public static void main(String[] args)
    {
        One2ManyExample one2ManyExample = new One2ManyExample();
        one2ManyExample.initializeConnector();
        try
        {
            one2ManyExample.patch();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        try
        {
            one2ManyExample.persist();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        try
        {
            One2ManyParentEntity entity = one2ManyExample.retrieve(id);
            System.out.println("entity.Name() = " + entity.getName());
            for (One2ManyChildEntity childEntity : entity.getChildEntities())
            {
                System.out.println("entity.ChildName() = " + childEntity.getName());
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        one2ManyExample.destroyConnector();
    }
}