Is it possible to have an enum field in a class persisted with OrmLite?

Question

I'm trying to persist the following class with OrmLite:

public class Field {
    @DatabaseField(id = true)
    public String name;

    @DatabaseField(canBeNull = false)
    public FieldType type;
    ...
}

The FieldType is a public enum. The field, corresponding to the type is string in SQLite (is doesn't support enums). When I try to use it, I get the following exception:

INFO [main] (SingleConnectionDataSource.java:244) - Established shared JDBC Connection: org.sqlite.Conn@5224ee
Exception in thread "main" org.springframework.beans.factory.BeanInitializationException: Initialization of DAO failed; nested exception is java.lang.IllegalArgumentException: Unknown field class class enums.FieldType for field FieldType:name=type,class=class orm.Field
 at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:51)
 at orm.FieldDAO.getInstance(FieldDAO.java:17)
 at orm.Field.fromString(Field.java:23)
 at orm.Field.main(Field.java:38)
Caused by: java.lang.IllegalArgumentException: Unknown field class class enums.FieldType for field FieldType:name=type,class=class orm.Field
 at com.j256.ormlite.field.FieldType.<init>(FieldType.java:54)
 at com.j256.ormlite.field.FieldType.createFieldType(FieldType.java:381)
 at com.j256.ormlite.table.DatabaseTableConfig.fromClass(DatabaseTableConfig.java:82)
 at com.j256.ormlite.dao.BaseJdbcDao.initDao(BaseJdbcDao.java:116)
 at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:48)
 ... 3 more

So how do I tell OrmLite, values on the Java side are from an enum?

Solution

ORMLite can persist enums either as the VARCHAR enum name (default):

// this saves it as a string in the database
@DatabaseField
OurEnum ourEnum;
...
private enum OurEnum {
    FIRST,
    SECOND, ;
}

As an alternative, you can save the ordinal INTEGER.

// this saves it as an integer in the database
@DatabaseField(dataType = DataType.ENUM_INTEGER)
OurEnum ourEnum;

Although you can store the ordinal, the VARCHAR name version (which is the default) is recommended since the ordinal value can change if you add or remove entries from the enum.

For both enum types, you can specify an unknownEnumName = "..." field which helps with forward and backward compatibility. If the database contains an unknown value for the enum then the object that is returned by the DAOs will have this enum value.

@DatabaseField(unknownEnumName = "FIRST")
OurEnum ourEnum;

Comments

[htf]

Thanks, you're doing great job, anyways do you think it would be better to contact you via the form or this site? I guess the latter could save your time when people google for what they want first

[pablisco]

Why is it recommended to use ENUM_INTEGER? Surely, the name of the enum entry is less likely to change than the order or amount of entries.

[pablisco]

Ah! sorry. My bad, I miss read it :) since it was after talking about ENUM_INTEGER my brain thought that next paragraph was talking about ENUM_INTEGER and not VARCHAR