Question

I created database, for my android app, witch has 16 tables. I want to use ORMlite mapping. The problem is that I didn’t find examples where you have composite id(Multiple primary keys). For example I have table:

CREATE  TABLE IF NOT EXISTS `Tourist_Guide`.`Cultural_activity` (
  `City_Id` INT NOT NULL ,
  `activity_Id` INT NOT NULL ,
  `Cultural_activity_Id` INT NOT NULL AUTO_INCREMENT ,
  `Name_Of_Cultural_activity` VARCHAR(30) NOT NULL ,
  PRIMARY KEY (`Cultural_activity_Id`, `City_Id`, `activity_Id`) ,
  INDEX `fk_Cultural_activity_activity1` (`City_Id` ASC, `activity_Id` ASC) ,
  CONSTRAINT `fk_Cultural_activity_activity1`
    FOREIGN KEY (`City_Id` , `activity_Id` )
    REFERENCES `Tourist_Guide`.`activity` (`City_Id` , `activity_Id` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

Can you, please, tell me how to map this table to class(how this class should look like), is that even possible?

Answer 1

Limitations

For simplicity, and to be able to have the same POCO class persisted in db4o, memcached, redis or on the filesystem (i.e.
providers included in ServiceStack), each model must have a single
primary key, by convention OrmLite expects it to be Id although you
use [Alias("DbFieldName")] attribute it map it to a column with a
different name or use the [PrimaryKey] attribute to tell OrmLite to
use a different property for the primary key.

You can still SELECT from these tables, you will just be unable to
make use of APIs that rely on it, e.g. Update or Delete where the
filter is implied (i.e. not specified), all the APIs that end with
ById, etc.

Workaround single Primary Key limitation

A potential workaround to support tables with multiple primary keys is
to create an auto generated Id property that returns a unique value
based on all the primary key fields, e.g:

public class OrderDetail
{
    public string Id { get { return this.OrderId + "/" + this.ProductId; } }

    

public int OrderId { get; set; }
    public int ProductId { get; set; }
    public decimal UnitPrice { get; set; }
    public short Quantity { get; set; }
    public double Discount { get; set; }
}

https://github.com/ServiceStack/ServiceStack.OrmLite/#limitations