[英]Nhibernate mapping a class which has a generic list property
我是Nhibernate的新手,我正在嘗試使用Nhibernate映射具有通用列表屬性的類(發票),但我不斷收到錯誤消息:“表InvoiceDetails中的關聯引用了未映射的類:System.Int32”。 因為每個發票都有更多詳細信息,所以我在發票和InvoiceDetails表之間具有一對多的聯系。
詳細信息:a)發票類別:
public class Invoice
{
private IList<InvoiceDetail> _invoiceDetails = new List<InvoiceDetail>();
public virtual int InvoiceID { get; set; }
public virtual string SerialNumber { get; set; }
public virtual string Number { get; set; }
public virtual DateTime InvoiceDate { get; set; }
public virtual decimal Amount { get; set; }
public virtual IList<InvoiceDetail> InvoiceDetails
{
get { return _invoiceDetails; }
set { _invoiceDetails = value; }
}
public virtual Customer customer { get; set; }
public virtual Institution Institution { get; set; }
public virtual Receipt receipt { get; set; }
public virtual bool IsDeleted { get; set; }
}
b)InvoiceDetail類:
public class InvoiceDetail
{
public virtual int InvoiceDetailID { get; set; }
public virtual int InvoiceID { get; set; }
public virtual string ServiceDescription { get; set; }
public virtual string Unit { get; set; }
public virtual int Quantity { get; set; }
public virtual double Value { get; set; }
public virtual bool IsDeleted { get; set; }
}
c)發票映射文件:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyProject" namespace="MyProject.Model">
<class name="Invoice" table="Invoices">
<id name="InvoiceID" column="InvoiceID" type="int">
<generator class="native"></generator>
</id>
<property name="SerialNumber" column ="InvoiceSerialNumber"/>
<property name="Number" column ="InvoiceNumber"/>
<property name="InvoiceDate"/>
<property name="Amount"/>
<property name="IsDeleted" />
<many-to-one name="Institution" column="InstitutionID" />
<bag name="InvoiceDetails" access="nosetter.camelcase"
inverse ="true" lazy ="false" cascade="all-delete-orphan">
<key column="InvoiceID"/>
<many-to-one class="MyProject.Model.InvoiceDetail, MyProject"/>
</bag>
</class>
</hibernate-mapping>
d)InvoiceDetail映射文件:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyProject" namespace="MyProject.Model">
<class name="InvoiceDetail" table="InvoiceDetails">
<id name="InvoiceDetailID" column="InvoiceDetailID" type="int">
<generator class="native"></generator>
</id>
<many-to-one name="InvoiceID" column="InvoiceID" />
<property name="ServiceDescription"/>
<property name="Unit"/>
<property name="Quantity"/>
<property name="Value"/>
<property name="IsDeleted" />
</class>
</hibernate-mapping>
看起來還不錯!
您需要修復InvoiceDetail.InvoiceID
屬性。 對於多對一屬性,您應該將它們建模為對父實體的引用,而不是像包含ID的簡單值屬性一樣。 您使用Invoice.Institution
正確了。
在InvoiceDetail
,替換此...
public virtual int InvoiceID { get; set; }
... 有了這個:
public virtual Invoice Invoice { get; set; }
同樣,在您的映射中,替換此...
<many-to-one name="InvoiceID" column="InvoiceID" />
... 有了這個:
<many-to-one name="Invoice" column="InvoiceID" />
另外,袋子不能是多對一的,應該是一對多的。 請參閱文檔 。 取代這個...
<bag name="InvoiceDetails" access="nosetter.camelcase" inverse ="true" lazy ="false" cascade="all-delete-orphan">
<key column="InvoiceID"/>
<many-to-one class="MyProject.Model.InvoiceDetail, MyProject"/>
</bag>
... 有了這個:
<bag name="InvoiceDetails" access="nosetter.camelcase" inverse ="true" lazy ="false" cascade="all-delete-orphan">
<key column="InvoiceID"/>
<one-to-many class="MyProject.Model.InvoiceDetail, MyProject"/>
</bag>
最后一點:請注意lazy =“ false”。 如果您打算提高性能,那就讓NHibernate急切地獲取那些相關記錄,這不是做到這一點的方法。 有關為什么會出現此問題的說明,請參見http://ayende.com/blog/4573/nhibernate-is-lazy-just-live-with-it 。 請參閱http://nhibernate.info/doc/nh/en/index.html#performance-fetching,以了解各種正確實現此方法的方法。
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