C# 如何在fluent Nhibernate 4中进行简单的表联接

我试图找出如何连接两个表Node和NodeDetails，它们有一个外键将它们关联起来。基本上，我正在寻找这个sql查询的nhibernate linq版本：

SELECT node.ObjectType, nodeDetails.Name, nodeDetails.SizeInFeet
FROM node
left join nodeDetails
on node.ID = nodedetails.nodeID
ORDER BY node.ObjectType;

因为我正在进行连接，并且不需要所有列，所以我创建了另一个名为NodeDetailsView的实体，该实体应该保存结果。我的C代码如下所示：

Node n = null;
NodeDetails nd = null;

var q = _session.QueryOver<NodeDetails>(() => nd)
    .JoinQueryOver(x => x.NodeID, () => n)
    .TransformUsing(Transformers.AliasToBean<NodeDetailsView>());

 IList<NodeDetailsView> r = t.List<NodeDetailsView>();

using NHibernate.Linq

IList<NodeDetailsView> r = _session.Query<NodeDetails>()
                .Select(x => new NodeDetailsView
                       {
                           ObjectType = x.NodeID.ObjectType,
                           SizeInFeet = x.SizeInFeet,
                           TotalSpace = "not sure what this is..."
                       }
                .ToList()

Nodetail.cs

public class NodeDetails : IVersionedEntity
{
    public virtual int ID { get; set; }
    public virtual Node NodeID { get; set; }
    public virtual int SizeInFeet { get; set; }
    public virtual float Price { get; set; }
}

视图类NodeDetailsView.cs

public class NodeDetailsView
{
    public virtual string ObjectType { get; set; }
    public virtual string SizeInFeet { get; set; }
    public virtual int TotalSpace { get; set; }
}

流畅映射

public class NodeMap: ClassMap<Node>
{
    public WorldObjectMap()
    {
        Id(x => x.ID);
        Map(x => x.ObjectType).Not.Nullable();
        Map(x => x.Location).Not.Nullable();
    }
}

public class NodDetailsMap : ClassMap<NodeDetails>
{
    public NodDetailsMap()
    {
        Id(x => x.ID);
        References(x => x.NodeID).Column("ID");
        Map(x => x.MarketPrice).Nullable();
        Map(x => x.SizeInFeet).Nullable();
    }
}

public class NodeDetailsViewMapping : ClassMap<NodeDetailsView>
{
    public WorldObjectLeasesViewMapping()
    {
        Map(x => x.ObjectType).Not.Nullable();
        Map(x => x.Name).Nullable();
        Map(x => x.SizeInFeet);
    }
}

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老实说，我会使用Linq提供程序而不是QueryOver。如果你这样做了，它会像这样：

Node n = null;
NodeDetails nd = null;

var q = _session.QueryOver<NodeDetails>(() => nd)
    .JoinQueryOver(x => x.NodeID, () => n)
    .TransformUsing(Transformers.AliasToBean<NodeDetailsView>());

 IList<NodeDetailsView> r = t.List<NodeDetailsView>();

using NHibernate.Linq

IList<NodeDetailsView> r = _session.Query<NodeDetails>()
                .Select(x => new NodeDetailsView
                       {
                           ObjectType = x.NodeID.ObjectType,
                           SizeInFeet = x.SizeInFeet,
                           TotalSpace = "not sure what this is..."
                       }
                .ToList()

无需映射NodeDetailsView，因为这似乎是一个DTO/模型。只能映射代表数据库表或视图的对象

---

从上面可以看出，SizeInFeet因对象而异。一个是字符串，另一个是int。如果确实是这种情况，您必须在查询中使用类似于SizeInFeet=x.SizeInFeet的内容进行转换。ToString

QueryOver是QueryOver，一种特定于NHibernate的API，而不是LINQ。如果要使用LINQ，请从session.Query开始。还要注意，FluentNHibernate只是一个定义映射的API，稍后在执行查询时不涉及它。你真正想问的是如何在NHibernate？中查询X？。科尔下面的回答似乎很好。