I used to use the GetDbCount() function of the adapter to retrieve a "VirtualRecordCount" for a query in order to prepare the paging controls. It was pretty straight forward as I would just pass it the same IRelationPredicateBucket that I would pass FetchEntityCollection.

I can't quite work out how I would do that using QuerySpec.

Here is a sample of the old code (version 2.6):

            // Entity collection that will hold the query result
            var tickerItems = new EntityCollection<NewsTickerItemEntity>();

            if (pagingOptions == null)
                pagingOptions = new DataPagerOptions(0, false);

            // Execute the query against the data store
            Adapter.FetchEntityCollection(tickerItems, bucket, maxRecords, sortExpression, prefetchPath, includeExcludeFields,
                                          pagingOptions.CurrentPage, pagingOptions.PageSize);

            if (pagingOptions.SetVirtualCount)
            {
                var virtualCount = Adapter.GetDbCount(tickerItems, bucket);
                PagingData = new DataPager(virtualCount, pagingOptions);
            }

            return tickerItems;

If you already have a query 'q' you just want to "count", then just do this:

using (var adapter = new DataAccessAdapter())
{
    count = adapter.FetchScalar<int>(qf.Create().Select(q.CountRow()));
}

Interesting, I'll give that a try. I've had to move away from QuerySpec for the moment because I can't include specific fields without 'q' becoming a DynamicQuery instead of a EntityQuery<T>.

trancehead wrote:

Interesting, I'll give that a try. I've had to move away from QuerySpec for the moment because I can't include specific fields without 'q' becoming a DynamicQuery instead of a EntityQuery<T>.

Could you give an example why that would be a problem? I.e. if you want to fetch all Order fields + 3 Customer fields, that obviously doesn't fit in an orderentity (so you need a custom projection), hence the Dynamicquery requirement.

I want to fetch a collection of NewsEntity but I only need the title and the date (not the other fields).

I'm not sure whether you want to fetch specific fields from more than one Entity. Or you want to fetch specific fields from one Entity.

i.e. specific fields from 2 tables, or from a single table.

My two cents added to what everyone said: If you want include just some fields or exclude some others, you can use QuerySpec's Include/Exclude functions:

// include relevant fields
var q = qf.Order
    .Include(OrderFields.OrderId, OrderFields.OrderDate);

// exclude expensive fields
var q = qf.Employee
    .Exclude(EmployeeFields.Photo);

@daelmo I thought the include/exclude methods were for something else entirely. That makes a lot more sense now, thanks.