如何在流利的NHibernate中加入表 [英] How to join table in fluent nhibernate

问题描述

我们该怎么做此映射但是流利吗?

how do we do this mapping but fluently?

<class name="Person" table="People">

    <id name="Id">
        <generator class="identity"/>
    </id>

    <property name="Name" />

    <join table="Addresses">
        <key column="PersonId"/>
        <property name="Line1"/>
        <property name="Line2"/>
        <property name="City"/>
        <property name="Country"/>
        <property name="ZipCode"/>
    </join>

</class>

我知道我可以使用参考"，但是我不需要相关表中的所有列.我只需要一个属性.

I know i can use 'References' but i don't need all the columns from the related table. i just need one property.

推荐答案

Paco说的不对.这可以在Fluent NHibernate中完成. 我自己上网搜索了很长时间，找不到任何人在谈论这个选项，所以我只是和FNHibernate一起玩了一段时间，最后设法做到了.

What Paco said is not right. This can be done in Fluent NHibernate. I searched the web myself quite a while, couldn't find anyone talking about this option, so I just played around with FNHibernate a little and finally managed to do it.

这是我的情况:

我有两个表-

"FormFields" => Columns { "FieldId", "FieldName", "FieldType", "DisplayOrder" }
"FormStructure" => Columns { "FormId", "FormType", "FieldId" }

这些是我的实体:

public class FormStructure
{
    public virtual Int32 FormId { get; private set; }
    public virtual Int32 FormType { get; set; }
    public virtual FormField FieldId { get; set; }
}

public class FormField
{
    public virtual int FieldId { get; private set; }
    public virtual String FieldName { get; set; }
    public virtual int? FieldType { get; set; }
    public virtual int? DisplayOrder { get; set; }
}

我的查询中有几种方法可以返回FormStructure对象的列表.我希望这些方法可以使它们按FormField对象中的DisplayOrder字段排序，并且还希望出于其他原因，DisplayOrder可以作为我的FormStructure对象中的属性使用.

I have a couple of methods in my query that return a list of FormStructure objects. I wanted these methods to give me them ordered by the DisplayOrder field in the FormField object, and wanted the DisplayOrder available as a property in my FormStructure object for other reasons as well.

这基本上意味着我需要连接表，以便我可以从FormStructure表中检索所有列以及FormField表中的DisplayOrder列，并将它们连接到匹配的FieldId列上.

This basically means I needed to join the tables so that I would retrieve all the columns from the FormStructure table along with the DisplayOrder column from the FormField table, joining them on the matching FieldId columns.

我为解决这个问题所做的事情:

What I did to solve this :

1. 我在FormStructure对象中添加了一个名为DisplayOrder的属性.

1. I added a property called DisplayOrder to my FormStructure object.

public virtual int? DisplayOrder { get; set; }

我在FormStructure映射类中添加了Join方法，因此它看起来像这样.

I added the Join method to my FormStructure mapping class so it looked like this.

public class FormStructureMap : ClassMap<FormStructure>
{
    public FormStructureMap()
    {
        Table("FormStructure");

        Id(x => x.Id);
        Map(x => x.FormType);
        References(x => x.Schedule).Column("ScheduleId");
        References(x => x.Field).Column("FieldId");
        Map(x => x.IsMandatory).Nullable();

        Join("FormFields", m =>
        {
            m.Fetch.Join();
            m.KeyColumn("FieldId");
            m.Map(t => t.DisplayOrder).Nullable();
        });
    }
}

Join方法显然会在Join的KeyColumn方法中定义的列的两个表之间进行连接.

The Join method will obviously join between the two tables on the column you defined in the KeyColumn method within the Join.

这还将删除一些具有空值的行.为了避免这种情况(我最近遇到过这种情况)，可以在Join方法内添加m.Optional();.

This will also remove some of the rows that have null values. In order to avoid this (I ran into this recently) you can add m.Optional(); inside the Join method.

我现在可以检索FormStructure对象的列表，按DisplayOrder对其进行排序，甚至可以在FormStructure对象中将DisplayOrder作为属性使用.

I could now retrieve a list of FormStructure objects, order them by DisplayOrder and even have DisplayOrder available as a property in the FormStructure object.

return session.CreateCriteria<FormStructure>()
              .Add(Expression.Eq("FieldName", fieldName))
              .AddOrder(Order.Asc("DisplayOrder"))
              .List<FormStructure>();

以前不可能完成此操作，因为它无法识别我在那里的Order子句中的DisplayOrder列.

This couldn't have been done before, because it wouldn't have recognized the DisplayOrder column in the Order clause I have there.

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