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Custom data type Converter
Supported by ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
A converted data type is a simple DataType<U< where a Converter<T, U> converts from some Built-in data types to a custom data type. The simplest way to get a DataType<U< reference is by calling:
dataType.asConvertedDataType(converter)
Where a org.jooq.Converter must implement at least these four methods:
public interface Converter<T, U> {
// Your conversion logic goes into these two methods, that can convert
// between the database type T and the user type U in both directions:
U from(T databaseObject);
T to(U userObject);
// You need to provide Class instances for each type, too:
Class<T> fromType();
Class<U> toType();
}
Or, using a specific example:
record Email(String email) {}
// Using a simpler, functional API:
Converter<String, Email> emailConverter = Converter.of(
String.class,
Email.class,
// Converting String -> Email
Email::new,
// Converting Email -> String
Email::email
);
DataType<Email> emailType = VARCHAR.asConvertedDataType(emailConverter);
In most practical cases, the DataType<U< does not need to be denoted like this. Instead, a re-usable Converter class is attached to the generated EMAIL columns throughout the schema using forced types configuration. However, when using plain SQL, this API usage can be useful:
// Plain SQL template based
Field<Email> f1 = DSL.field("my_table.my_email_column", emailType);
// Name based
Field<Email> f2 = DSL.field(name("my_table", "my_email_column"), emailType);
In many cases, converters are single use and single direction only (e.g. fetching only). In those cases, there exists convenience API that is much less verbose to use, see ad-hoc converters for details.
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