How to retrieve the java data types of columns from the database using Hibernate ?

Question

I want to retrieve the java data types of the columns of a table in MySql using hibernate so that I can dynamically convert my input data to corresponding data type while inserting into database.

One way is to read the class-name.hbm.xml and retrieve the data type information but I want the data types straight from the database and not from any config XMLs as the XMLs can be erroneous.

Another way is using AbstractEntityPersister.getPropertyType(column-name).toString() but that returns the hibernate data type instead of the corresponding java types.

Is there any way I can achieve this ?

Answer 1

You can use AbstractEntityPersister.getPropertyColumnNames(...), then issue a raw JDBC query on that column and use ResultSet.getColumnType()

Answer 2

Do the following (bit hacky tho)

    Class clazz = ...;
    SessionFactory sessionFactory = ...;

    ClassMetadata classMetadata = sessionFactory.getClassMetadata( clazz );

    // bit of a hack, relies on knowing that SessionFactoryImpl implements Mapping
    Mapping mapping = (Mapping)sessionFactory;

    for ( String propertyName : classMetadata.getPropertyNames() )
    {
        Type type = classMetadata.getPropertyType( propertyName );

        if ( type.isCollectionType() )
            continue;

        // TODO: do something with the result
        type.sqlTypes( mapping );
    }

Answer 3

I achieved the required functionality by querying the ColumnsMetaData table from information_schema (a schema containing MySQL's Data Dictionary)