Cannot get foreign reference with composite primary keys to work

[rhegner]

The following minimal example program produces a InvalidOperationException exception:

using NPoco;
using System;

namespace NPocoTest
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var db = new NPoco.Database("<your connection string>", DatabaseType.MySQL, MySql.Data.MySqlClient.MySqlClientFactory.Instance))
            {
                var productInstances = db.Query<ProductInstance>().Include(pi => pi.SelectedFeatureSet).ToList();
            }
        }
    }

    [TableName("product_instance")]
    [PrimaryKey("product_id,product_instance_id", AutoIncrement = false)]
    public class ProductInstance
    {
        [Column("product_id")]
        public Guid ProductId { get; set; }

        [Column("product_instance_id")]
        public Guid ProductInstanceId { get; set; }

        [Column("selected_feature_set_id")]
        public Guid? SelectedFeatureSetId { get; set; }

        [Reference(ReferenceType.Foreign, ColumnName = "product_id,selected_feature_set_id", ReferenceMemberName = "ProductId,FeatureSetId")]
        public FeatureSet SelectedFeatureSet { get; set; }

    }

    [TableName("feature_set")]
    [PrimaryKey("product_id,feature_set_id", AutoIncrement = false)]
    public class FeatureSet
    {
        [Column("product_id")]
        public Guid ProductId { get; set; }

        [Column("feature_set_id")]
        public Guid FeatureSetId { get; set; }
    }

}

Is there a mistake in my Reference attribute, or is there a bug in NPoco?

Here's the full stack trace:

Sequence contains no matching element
   at System.Linq.ThrowHelper.ThrowNoMatchException()
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
   at NPoco.Linq.ComplexSqlBuilder`1.GetJoinExpressions(Expression expression, String tableAlias, JoinType joinType)
   at NPoco.Linq.AsyncQueryProvider`1.QueryProviderWithIncludes(Expression expression, String tableAlias, JoinType joinType)
   at NPoco.Linq.AsyncQueryProvider`1.Include[T2](Expression`1 expression, JoinType joinType)
   at NPoco.Linq.QueryProvider`1.Include[T2](Expression`1 expression, JoinType joinType)
   at NPocoTest.Program.Main(String[] args) in C:\Robert\Temp\NPocoTest\Program.cs:line 12

[rhegner]

Ok I did dig a little bit into the NPoco source code. It looks like ComplexSqlBuilder.GetJoinExpressions does not support (comma separated) composite keys.

It looks like it would be relatively easy to enhance the onSql expression to compare multiple columns. So I could probably provide a pull request for that. But there is also the other part of GetJoinExpressions which populates a JoinData object, and I don't understand the bigger context of that and whether that object would also need to be aware of the composite key. @schotime can you advise?

[lindeberg]

I cant get foreign keys to work at all. Keep getting Sequence contains no matching element.