Primary Key Types

For every table with a primary key, Typr generates a distinct ID type. This prevents mixing up IDs from different tables—a common source of bugs.

Simple Primary Keys

A table with a single-column primary key gets a wrapper type:

CompanyId

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2SQLite

JavaKotlinScala

Full file

/** Type for the primary key of table `showcase.company` */
public record CompanyId(String value) {
  public CompanyId withValue(String value) {
    return new CompanyId(value);
  }

  @Override
  public java.lang.String toString() {
    return value.toString();
  }

  static public Bijection<CompanyId, String> bijection =
    Bijection.of(CompanyId::value, CompanyId::new);

  static public PgType<CompanyId> pgType =
    PgTypes.text.to(Bijection.of(CompanyId::new, CompanyId::value));

  static public PgType<List<CompanyId>> pgTypeArray =
    pgType.array();
}

The wrapper ensures you can't accidentally pass a CustomerId where a CompanyId is expected. The compiler catches these mistakes.

Composite Primary Keys

Tables with multi-column primary keys get a composite ID type:

ProjectAssignmentId

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2SQLite

JavaKotlinScala

Full file

/** Type for the composite primary key of table `showcase.project_assignment` */
public record ProjectAssignmentId(
  EmployeeId employeeId,
  ProjectId projectId
) implements Tuple2<EmployeeId, ProjectId> {
  public ProjectAssignmentId withEmployeeId(EmployeeId employeeId) {
    return new ProjectAssignmentId(employeeId, projectId);
  }

  public ProjectAssignmentId withProjectId(ProjectId projectId) {
    return new ProjectAssignmentId(employeeId, projectId);
  }

  public static RowCodec<ProjectAssignmentId> rowCodec = RowCodecs.of(EmployeeId.pgType, ProjectId.pgType, ProjectAssignmentId::new, row -> new Object[]{row.employeeId(), row.projectId()});

  @Override
  public EmployeeId _1() {
    return employeeId;
  }

  @Override
  public ProjectId _2() {
    return projectId;
  }
}

The composite type bundles all key columns together, making it easy to pass around and use in lookups.

Using ID Types

ID types integrate with repositories for type-safe lookups:

CompanyRepo

PostgreSQLMariaDBDuckDBOracleSQL ServerDB2SQLite

JavaKotlinScala

Full file

  Optional<CompanyRow> selectById(
    CompanyId id,
    ConnectionRead c
  );

Disabling ID Types

If you don't want wrapper types for certain tables, configure enablePrimaryKeyType:

Options options = new Options(
    "mypkg",
    Lang.Java,
    // ... other options
    Selector.relationNames("legacy_table"), // Only generate ID types for this table
);

Use Selector.All (default) for all tables, Selector.None to disable, or Selector.relationNames(...) for specific tables.

Composite ID types are always generated regardless of this setting.