Create table with Foreign Collection Field

I have this abstract class:

DomainItem

abstract public class DomainItem {

    @DatabaseField(generatedId = true)
    protected long id;

    @ForeignCollectionField(eager = false)
        protected ForeignCollection<ContentItem> contentItens;

    //getters and setters
}

ContentItem:

abstract public class ContentItem {

    @DatabaseField(generatedId = true)
    protected long id;

    @DatabaseField(foreign = true)
    protected DomainItem domainItem;


    @DatabaseField()
    protected String content;

    //getters and setters
}

And these (no abstract):

@DatabaseTable()
public class PhytoterapicItem extends DomainItem{

    public PhytoterapicItem(){

    }

}

PhytoterapicContent

@DatabaseTable(tableName = "phytoterapiccontent")
public class PhytoterapicContent extends ContentItem {

    @DatabaseField(canBeNull = false)
    private String defaultName;

    @DatabaseField(canBeNull = false)
    private String scientificName;

    //getters and setters
}

In my DatabaseHelper I trying create the tables:

//DatabaseHelper
...
@Override
public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
    try {
        Log.i(TAG, "onCreate");
        TableUtils.createTable(connectionSource, PhytoterapicContent.class);
        Log.i(TAG, "Created table PhytoterapicContent");

        TableUtils.createTable(connectionSource, PhytoterapicItem.class);
        Log.i(TAG, "Created table PhytoterapicItem");
    catch{
       ...
    }

The table PhytoterapicContent is created. But I got the follow error:

java.sql.SQLException: Foreign collection class br.com.project.model.ContentItem for field 'contentItens' column-name does not contain a foreign field of class br.com.project.model.PhytoterapicItem

Solution

So the exception message was designed to help here. To quote it with the class names removed:

Foreign collection class ContentItem for field contentItens column-name does not contain a foreign field of class PhytoterapicItem

That looks to be the case. Whenever you have ForeignCollection, the class contained by the collection must have a foreign field back to the parent class.

In your case, PhytoterapicItem extends the DomainItem class which has a ForeignCollection of ContentItem objects. That means that ContentItem must have a foreign field of type PhytoterapicItem. Otherwise, how would ORMLite know which of the ContentItem items in the table are associated with a particular PhytoterapicItem.

The example of Account and Order objects in the foreign collection documentation may help you with your schema. Each Account has a foreign collection of Order objects. Whenever you query for an Account a separate query is performed to find the collection of Order objects that correspond to a particular Account. That means that each Order has to have a foreign Account object.