I had a problem with choosing special columns (properties), the code below:
Entities:
public class Item {
public Item() {
Images = new List<Image>();
}
public virtual int Id { get; set; }
public virtual int ItemNum { get; set; }
public virtual Channel Channel { get; set; }
public virtual string Title { get; set; }
public virtual string Comment { get; set; }
public virtual string Text { get; set; }
public virtual string Link { get; set; }
public virtual string Category { get; set; }
public virtual DateTime? PublishDate { get; set; }
public virtual string ExternalId { get; set; }
public virtual string SourceImage { get; set; }
public virtual string Bubble { get; set; }
public virtual IEnumerable<Image> Images { get; set; }
}
public class Image {
public Image() { }
private string type;
public virtual int Id { get; set; }
public virtual bool IsMobile { get; set; }
public virtual Item Item { get; set; }
public virtual string Type {get;set;}
public virtual string ImageUrl { get; set; }
public virtual int? Height { get; set; }
public virtual int? Width { get; set; }
public virtual int? ImgXOff { get; set; }
public virtual int? ImgYOff { get; set; }
public virtual decimal? ImgZoom { get; set; }
}
And now I would like to get only Item.Id and everything related to the string with this Id, my request
var minDate = DateTime.Today - TimeSpan.FromDays(config.ItemsFromLastDaysCount);
var items = session.Query<Item>()
.Fetch(x => x.Channel)
.Where(x => x.Channel.InsertionDate >= minDate)
.OrderByDescending(x => x.Channel.InsertionDate)
.Take(config.ItemsOnOnePage)
.Select(x => new
{
Id = x.Id,
Images = x.Images
}).ToList();
But such a request raises a strange exception:
"An exception of type" System.ArgumentException "occurred in System.Core.dll, but was not processed in user code
Additional information: an expression of type 'System.Collections.IList' cannot be used for a parameter of type 'System.Collections.Generic.IEnumerable`1 [System.Object]' "
Stack trace:
at System.Linq.Expressions.Expression.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arg, ParameterInfo pi)
at System.Linq.Expressions.Expression.ValidateArgumentTypes(MethodBase method, ExpressionType nodeKind, ReadOnlyCollection`1& arguments)
at System.Linq.Expressions.Expression.Invoke(Expression expression, IEnumerable`1 arguments)
at System.Linq.Expressions.Expression.Invoke(Expression expression, Expression[] arguments)
at NHibernate.Linq.ExpressionToHqlTranslationResults.MergeLambdasAndCompile(IList`1 transformations)
at NHibernate.Linq.ExpressionToHqlTranslationResults..ctor(HqlTreeNode statement, IList`1 itemTransformers, IList`1 listTransformers, IList`1 postExecuteTransformers, List`1 additionalCriteria)
at NHibernate.Linq.IntermediateHqlTree.GetTranslation()
at NHibernate.Linq.Visitors.QueryModelVisitor.GenerateHqlQuery(QueryModel queryModel, VisitorParameters parameters, Boolean root)
at NHibernate.Linq.NhLinqExpression.Translate(ISessionFactoryImplementor sessionFactory)
at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(String queryIdentifier, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory)
at NHibernate.Engine.Query.HQLExpressionQueryPlan.CreateTranslators(String expressionStr, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory)
at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory)
at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory)
at NHibernate.Engine.Query.QueryPlanCache.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters)
at NHibernate.Impl.AbstractSessionImpl.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow)
at NHibernate.Impl.AbstractSessionImpl.CreateQuery(IQueryExpression queryExpression)
at NHibernate.Linq.DefaultQueryProvider.PrepareQuery(Expression expression, IQuery& query, NhLinqExpression& nhQuery)
at NHibernate.Linq.DefaultQueryProvider.Execute(Expression expression)
at NHibernate.Linq.DefaultQueryProvider.Execute[TResult](Expression expression)
at Remotion.Linq.QueryableBase`1.GetEnumerator()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at TicTac.Service.Controllers.HomeController.Index() in d:\Projekty\Hypermedia\TicTac.RssReader\branches\TicTac.RssReader\TicTac.Service\Controllers\HomeController.cs:line 27
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41()
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49()
the exception is due to the line:
Images = x.Images
I will be very grateful for the answer.