Hibernate Custom Basic Type with Database Function

Question

I'm making a custom Hibernate type using AbstractSingleColumnStandardBasicType to automatically convert the SQL UDT into a Java type. The SQL uses database functions to construct and serialize the column data from BLOBs and/or CLOBs, and I want to hide that from a user. So they don't have to use @ColumnTransformer(read="_serializer(column_name)", write="_constructor(?)") for every column.

I've made types using the BLOB SqlTypeDescriptor and a custom JavaTypeDescriptor to do the conversion at the JDBC level, but how can I have my custom type wrap the column and parameters in the proper SQL functions? I'm not finding anything describing anything like this.

Edit: To make this more concrete, this UDT (SDE ST_GEOMETRY) must be build via database functions (ST_LineFromText) or the defined UDT constructor (ST_LineString). Likewise, to read them from the database, you have to "export" them into a certain format (ST_AsText) for Java to read it. The regular approach of reading the fields of the type doesn't work in this case.

So:

create table geo_lines (
  line SDE.ST_GEOMETRY
);

And:

@Entity
@Table(name="geo_lines")
public class GeoLine {
  @Column(name="line")
  @Type(type="org.example.MyStLineType")
  // i'm wanting to be able to omit the following annotation
  @ColumnTransformer(read="SDE.ST_AsText(line)", 
         write="SDE.ST_ST_LineFromText(?, 3857)")
  private Polyline line;
}

So, all my type really needs from the user is the number (3857 in this case), which can be passed as a parameter, and everything else is standard boilerplate for any line. Repeat for the other types like points, polygons, etc.

Gaddis

What do you mean by saying wrap the column and parameters in the proper SQL functions? – Samantha

Generally you can annotate the entity class getter with @org.hibernate.annotations.Type(type = "your.custom.DataType") – Samantha

Indeed. I haven't given you enough information. See edit. – Gaddis

Seems like this should work by what you've described, unless you want the 3857 to be a parameter. The @ColumnTransformer(write) must only have one question mark. It is checked by the regular expression in org.hibernate.cfg.Ejb3Column#initMappingColumn function. – Chide