MediaCopy (Student Root 5.1.0-SNAPSHOT API)

java.lang.Object
- ejava.examples.orm.rel.annotated.MediaCopy

```
@Entity
public class MediaCopy
extends Object
```
This class provides an example of a ManyToOne mapping. The media copy owns the relationship to the media. Therefore the foreign key to media is within the media copy database table.
This class has an unrelated technical issue worth mentioning. Everything would have worked out fine if we created a simple primary key field for the media copy and a separate foreign key to the media. Instead, we pretended to encounter a composite primary key where one of the values doubled as the foreign key to the media.
```
 MediaCopy (pk=MEDIACOPY_MID + COPYNO)
     MEDIACOPY_MID (fk to Media.MEDIA_ID) 
     COPYNO
     ...
 Media (pk=MEDIA_ID)
     MEDIA_ID
     ...
 
```
The MediaCopy now has two uses for the MEDIACOPY_MID column. One as a primary key (part of a compound primary key) and the other as the foreign key to the Media. We need to make sure the provider preserves the semantics of the primary key while reusing it from the foreign key. This implementation will use the JPA 1.0 technique of mapping both the primary and foreign key properties to the same column and then mark the foreign key as READ-ONLY using the insertable and updatable properties of the @Column.

Field Summary

Fields
Modifier and Type Field Description

private int copyNo

private static org.slf4j.Logger log

private Media media

private long mediaId

Constructor Summary

Constructors
Modifier Constructor Description

protected MediaCopy()

MediaCopy(Media media, int copyNo)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`getCopyNo()`
`Media`	`getMedia()`
`long`	`getMediaId()`
`private String`	`myInstance()`
`private void`	`setCopyNo(int copyNo)`
`private void`	`setMedia(Media media)`
`private void`	`setMediaId(long mediaId)`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

log

private static final org.slf4j.Logger log

copyNo
```
private int copyNo
```

mediaId
```
private long mediaId
```

media
```
private Media media
```

Constructor Detail

MediaCopy
```
protected MediaCopy()
```

MediaCopy

public MediaCopy(Media media,
                 int copyNo)

Method Detail

getCopyNo
```
public int getCopyNo()
```

setCopyNo

private void setCopyNo(int copyNo)

getMediaId
```
public long getMediaId()
```

setMediaId

private void setMediaId(long mediaId)

getMedia
```
public Media getMedia()
```

setMedia

private void setMedia(Media media)

myInstance
```
private String myInstance()
```

toString
```
public String toString()
```
Overrides:

toString in class Object