Hello everybody,
currently, I am working with OpenJPA in the Spring framework and try to
implement the following:
I inherit certain subclasses from a mainclass. All these classes should be
mapped to a single table, so I use InheritanceType.SINGLE_TABLE and add a
discriminator value to each subclass.
Simplified, it looks like this:
@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="doc_type",
discriminatorType=DiscriminatorType.STRING)
public abstract class Document {
// ...
}
@Entity
@DiscriminatorValue(value="Magazine")
public class Magazine extends Document {
// ...
}
@Entity
@DiscriminatorValue(value="Book")
public class Book extends Document {
// ...
}
Unfortunately, I get the following error message when I try to load data from
the database:
Exception in thread "main" org.springframework.dao.InvalidDataAccessApiUsageE
xception: Could not map discriminator value "Book" to any known subclasses of
the requested class "project.entities.Document" (known discriminator values:
[Document, Magazine]).; nested exception is <openjpa-1.2.1-r752877:753278
nonfatal user error> org.apache.openjpa.persistence.ArgumentException: Could
not map discriminator value "Book" to any known subclasses of the requested
class "project.entities.Document" (known discriminator values: [Document,
Magazine]).
It seems that there are only known the main class and the subclass "Magazine",
but there is a problem with "Book" (and some other classes inherited from
"Document").
I do not have much experience with OpenJPA and Spring and thus I have no clue
how to solve this problem. Anybody out there who has an idea or maybe had a
similar problem?
Is there maybe something special I could have used accidentally for "Magazine",
but not for the other classes?
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