StaTypPocoQueries not working with PetaPoco fluent configuration

Question

I'm testing PetaPoco as an alternative to Fluent NHibernate and I added the extension StaTypPocoQueries.PetaPoco to use lambda expressions to build queries, just like Fluent NHibernate.

I don't want to create an instance of PetaPoco's Database class, so I made a Configuration Manager class to configure it when the program starts.

public class PetaPocoSessionManager
{
    public static string connectionString;

    public PetaPocoSessionManager()
    {
        connectionString = null;
    }

    public IDatabase CreateSession()
    {
        return DatabaseConfiguration.Build()
                    .UsingProvider<SqlServerDatabaseProvider>()
                    .UsingConnectionString(connectionString)
                    .UsingDefaultMapper<ConventionMapper>()
                    .WithAutoSelect()
                    .Create();
    }

}

And now in my repository class I build a method to query by some specific field.

[TableName("co")]
public class CustomerOrder
{
    public string OrderNumber { get; set; }
    public string CustomerNumber { get; set; }
    public decimal Price { get; set; }
    public DateTime OrderDate { get; set; }
    public string OrderType { get; set; }
    public string Status { get; set; }
    public string Warehouse { get; set; }
    public string OriginSite { get; set; }
    public string TakenBy { get; set; }
    public string ExportType { get; set; }
    public string Contact { get; set; }
    public string CurrencyCode { get; set; }
    public string TaxCode { get; set; }
}


public class CustomerOrderBL
{
    private IDatabase session;

    public CustomerOrderBL(IDatabase session)
    {
        this.session = session;
    }

    public CustomerOrder GetByCoNum(string coNum)
    {
        return session.FirstOrDefault<CustomerOrder>(x => x.CustomerNumber == coNum);
    }
}

However I got an error in the lambda expression that says "cannot convert lambda expression to type 'string' because it is not a delegate type". The thing is that I don't have that error if I use the classic PetaPoco configuration instead of fluent (this is, creating a new Database object per request).

Am I doing something wrong? Or StaTypPocoQueries is not compatible with fluent configuration?

Thanks in advance.

Answer 1

The extension method is for type Database and not IDatabase. I think this is why it's not resolving correctly.

Allow me to explain.

Because in your CustomerOrderBL class, you're referencing IDatabase and not Database, this is causing session.FirstOrDefault<CustomerOrder>(x => x.CustomerNumber == coNum) to resolve to T SingleOrDefault<T>(object primaryKey);, and not the extension method defined by the StaTypePocoQueries.PetaPoco package.

You could easily test this by using the following class

public class CustomerOrderBL
{
    private Database session;

    public CustomerOrderBL(Database session)
    {
        this.session = session;
    }

    public CustomerOrder GetByCoNum(string coNum)
    {
        return session.FirstOrDefault<CustomerOrder>(x => x.CustomerNumber == coNum);
    }
}

If this, as I have predicted, is the case the author Aaron Sherber of StaTypPocoQueries.PetaPoco helps out with PetaPoco a fair bit and is very active on GH. I'd open an issue to discuss it with him, as maybe he should be providing extensions for both Database and IDatabase