C# – Adding projections to an nhibernate query

cnhibernate

What would be the best way to add projections to an nhibernate query that already may or may not have 1 or more projections set? Calling .SetProjection() appears to replace any projections that may already be there.

To give a little background context I am using a version of the paged result extension method found here and I have come to a point where I am passing in a query with a distinct projection already but that projection is stripped for the count criteria because of calling .SetProjection(Projections.RowCountInt64).

Best Answer

I am not sure if it will work, because I can't check it right now, but why don't you use something like a ProjectionList to do this trick?


var criteria = ...
var projectionList = Projection.ProjectionList();

// Add you projections to the projectionList
projectionList.Add(yourQueryProjection);
projectionList.Add(Projections.RowCountInt64());

criteria.setProjection(projectionList);

Related Solutions

C# – LINQ query on a DataTable

You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so:

var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;

And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions

AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension.

Below is query with Lambda Expression,

var result = myDataTable
    .AsEnumerable()
    .Where(myRow => myRow.Field<int>("RowNo") == 1);

Nhibernate: left outer join on subquery

I'm not sure I entirly follow your issue but it sounds very similar to an issue I had. I seems that when you have the nested (sub) criteira with NHibernate you loose some of the control. I was able to get around my issue but aliasing my tables instead of using the nested criteira.

Possibly try...

criteria.CreateAlias("Cart", "Cart", JoinType.LeftOuterJoin);

and then your filter on the cart will have to be an OR condition

ICriterion cartCriterion = Restrictions.Eq("Cart.User", username);
customerCriterion = Restrictions.Or(customerCriterion, Restrictions.IsNull("Cart.User"));
criteria.Add(customerCriterion);

Let me know if that helps you out... if not... maybe post the SQL that your criteria above is generating and where it needs to change.

Good Luck

Best Answer

Related Solutions

C# – LINQ query on a DataTable

Nhibernate: left outer join on subquery

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