CODEWITHSUNDEEP
servicestackormlite-servicestack
npitou
npitou

Reputation: 35

Returning a Value Tuple of Custom Objects From Ormlite

I'm trying to do a simple Join on 2 tables and return a Value Tuple of those two tables.

public partial class DeliveryMethod
{
    [Required]
    [PrimaryKey]
    public int DeliveryMethodId { get; set; }
     [References(typeof(Event))]          
    [Required]
    public string EventId { get; set; }
     [References(typeof(DeliveryType))]          
    [Required]
    public short DeliveryTypeId { get; set; }
    [Required]
    public int MappedValue { get; set; }
}

public partial class DeliveryType
{
    [Required]
    [PrimaryKey]
    public short DeliveryTypeId { get; set; }
    [Required]
    public string DeliveryTypeDescription { get; set; }
}

public List<(DeliveryMethod deliveryMethod, DeliveryType deliveryType)> GetDeliveries(string eventId)
{
    using (var db = DbFactory.OpenDbConnection(...))
    {
        var q = db.From<DeliveryMethod>()
            .Join<DeliveryType>((dm, dt) => dm.DeliveryType == dt.DeliveryType)
            .Where(dm => dm.EventId == eventId)
            .Select<DeliveryMethod, DeliveryType>((dm, dt) =>
                new {dm, dt});
        return db.Select<(DeliveryMethod deliveryMethod, DeliveryType deliveryType)>(q);
    }
}

However, when I run this, I get a NullReferenceException. This seems to be because ConvertToValueTuple in OrmLiteUtils only has converters for basic types like string, int, DateTime, etc. and GetConverter(fieldType) returns null when it's a type of a custom object.

Is there a work around this? Or some way to return a value tuple of more complex, custom objects instead of just basic tuples like (int id, string name, DateTime time)?

P.S. I tried to simplify my problem by simplifying the classes so if I made a mistake there, I apologize for that but I think you can get the basic idea behind my question.

Upvotes: 2

Views: 200

Answers (1)

mythz
mythz

Reputation: 143374

You can only use OrmLite's C# 7 Tuple support by selecting columns, not entire tables, e.g:

.Select<DeliveryMethod, DeliveryType>((dm, dt) =>
    new {dm.EventId, dt.DeliveryMethodId});
var results = db.Select<(string, int)>(q);

For Selecting entire tables checkout OrmLite's SelectMulti API, e.g:

var q = db.From<DeliveryMethod>()
    .Join<DeliveryType>((dm, dt) => dm.DeliveryType == dt.DeliveryType)
    .Where(dm => dm.EventId == eventId);
var results = db.SelectMulti<DeliveryMethod, DeliveryType>();

Upvotes: 1

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