A simple lazy loading problem? Fluent NHibernate

Question

I have this mapper class. I'm no expert in lazy loading, so could you please enlighten me why sometimes it works and other times it doesn't. (The Id of the location is the problem)

public static class LocationMapper
{

    public static IEnumerable<DropDownItemView> ConvertToLocationViews
        (this IEnumerable<Location> Locations)
    {
        return Mapper.Map<IEnumerable<Location>, IEnumerable<DropDownItemView>>(Locations);
    }

    public static LocationFewDetailsView ConvertToLocationFewDetailsView(this Location loc)
    {
        LocationFewDetailsView location = new LocationFewDetailsView();
        location.CityName = loc.City.Name; //The lazy loading works here
        location.LocationId = loc.Id; // *But not here. The id is 0. What could be the problem?*
        location.LocationName = loc.Name; //The lazy loading works here
        return location;
    }
}

The mapping class:

using System;
using System.Collections.Generic;
using System.Text;
using FluentNHibernate.Mapping;
using Unde.Mergem.Model.EntityClasses;

namespace Unde.Mergem.Repository.NHibernate.Mappings
{
    /// Represents the mapping of the 'Location' entity, represented by the 'Location' class.
    public partial class LocationMap : ClassMap
    {
        /// Initializes a new instance of the  class.
        public LocationMap()
        {
            Table("[dbo].[LocationSet]");
            OptimisticLock.None();
            LazyLoad();

        Id(x=>x.Id)
            .Access.CamelCaseField(Prefix.Underscore)
            .Column("[Id]")
            .GeneratedBy.Identity();
        Map(x=>x.Address).Column("[Address]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.Capacity).Column("[Capacity]").Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.Description).Column("[Description]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.Map).CustomType("BinaryBlob").Column("[Map]").Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.MapUrl).Column("[MapURL]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.Name).Column("[Name]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);
        Map(x=>x.Website).Column("[Website]").Not.Nullable().Access.CamelCaseField(Prefix.Underscore);

        References(x=>x.City)
            .Access.CamelCaseField(Prefix.Underscore)
            .Cascade.All()
            .Fetch.Select()
            .Columns("[CityId]");
        HasMany(x=>x.Events)
            .Access.CamelCaseField(Prefix.Underscore)
            .Cascade.AllDeleteOrphan()
            .Fetch.Select()
            .Inverse()
            .LazyLoad()
            .KeyColumns.Add("[LocationId]");
        References(x=>x.Host)
            .Access.CamelCaseField(Prefix.Underscore)
            .Cascade.All()
            .Fetch.Select()
            .Columns("[HostId]");

        AdditionalMappingInfo();
    } 

    /// <summary>Partial method for adding additional mapping information in a partial class.</summary>
    partial void AdditionalMappingInfo();
}

}

It would be helpful to know the exception or specific problem. — Andy
– Andy, Commented May 26, 2011 at 16:19
There's no exception. "loc.Id" doesn't return the corect id (it returns 0) . The parameter from ConvertToLocationFewDetailsView(this Location loc) is of type Castle.Proxies.LocationProxy . Shouldn't loc.id be the id of my "real" object of type Location? (I hope I made myself clear) — Byronic Coder
– Byronic Coder, Commented May 26, 2011 at 17:01
can you check the generated sql on loc.Name, does it select the id too? Is Id still 0 when you switch line loc.Id and loc.Name ? — Firo
– Firo, Commented May 30, 2011 at 11:22

Community · Accepted Answer · 2017-05-23 12:19:59Z

0

If I can give you a suggestion I would avoid to use lazy loading in web enviroments as it decrease the performance.

have a look at:

When should one avoid using NHibernate's lazy-loading feature?

edited May 23, 2017 at 12:19

CommunityBot

11 silver badge

answered May 27, 2011 at 12:38

Massimiliano Peluso

26.8k6 gold badges65 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

A simple lazy loading problem? Fluent NHibernate

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related