JOOQ Cast String To Enum With Converter

While looking for a way to cast my String field into an Enum i stubled across the .cast() Method. When called it throws an SQLDialectNotSupportedException. Dialect has been Set to

Solution 1:

You cannot use cast() here because that would require jOOQ to understand how to cast your data type to your custom type in SQL. What you want to do is a client side conversion, and that is achieved ideally using a Converter.

Once you have implemented your Converter, the recommended way to use it is to attach it to generated code using the code generator: https://www.jooq.org/doc/latest/manual/code-generation/custom-data-types

<forcedType>
  <userType>java.time.DayOfWeek</userType>
  <converter>com.example.YourConverter</converter>
  <includeExpression>(?i:DAY_OF_WEEK)</includeExpression>
</forcedType>

If that's not an option, you can create a "converted" field reference as follows:

// I'm assuming you're storing the data as an INTEGER
DataType<DayOfWeek> type = SQLDataType.INTEGER.asConvertedDataType(new YourConverter());
Field<DayOfWeek> field = DSL.field("{0}", type, lecture.DAY_OF_WEEK);

// And now use that instead
create.select(field)...

But I really recommend attaching the converter to the generated code for most convience.