NHibernate.Mapping.Attributes - cannot set column order

vladimirak · **Joined:** Fri Jun 30, 2006 4:17 am **Posts:** 4

Hi,

I use NHibernate.Mapping.Attributes for mapping declarations and SchemaExport class for generating ddl. I've noticed that HbmSerializer always places <many-to-one> elements after <property> element. It's a real pain for me if I declare multicolumn unique keys or indexes with property and foreign key column. I cannot set correct column order:

Hibernate version: 1.2.0 Alpha 1
Class definition:

Code:

    
    [Class]
    public class Course
    {
        private int _id;
        [Id(0, Column="Id", TypeType = typeof(int) )]
            [Generator(1, Class = "native")]
        public virtual int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        private Product _product;
        [ManyToOne(0, ForeignKey="FK_Course_Product"),
            Column(1, Name = "ProductID", NotNull=true, UniqueKey = "0")]
        public virtual Product Product
        {
            get { return _product; }
            set { _product = value; }
        }

        private string _name;
        [Property (0),
           Column(1, Name = "Name", NotNull = true, Length=50, UniqueKey = "0")]
        public virtual string Name
        {
            get { return _name; }
            set { _name = value; }
        }
    }

Xml generated by HbmSerializer :

Code:

  <class name="Test.Domain.Course, Test.Core">
    <id column="Id" type="Int32">
      <generator class="native" />
    </id>
    <property name="Name">
      <column name="Name" length="50" not-null="true" unique-key="0" />
    </property>
    <many-to-one name="Product" foreign-key="FK_Course_Product">
      <column name="ProductID" not-null="true" unique-key="0" />
    </many-to-one>
  </class>

I expect unique key (ProductID, Name) so I need <column name="ProductID"> before <column name="Name">. How can I perform this?

KPixel · **Posted:** Sat Jul 01, 2006 2:06 pm

Do you mean that you want this?

Code:

  <class name="Test.Domain.Course, Test.Core"> 
    <id column="Id" type="Int32"> 
      <generator class="native" /> 
    </id> 
    <many-to-one name="Product" foreign-key="FK_Course_Product"> 
      <column name="ProductID" not-null="true" unique-key="0" /> 
    </many-to-one> 
    <property name="Name"> 
      <column name="Name" length="50" not-null="true" unique-key="0" /> 
    </property> 
  </class>

vladimirak · **Joined:** Fri Jun 30, 2006 4:17 am **Posts:** 4

Yes, I do. I really need this.

KPixel · **Posted:** Mon Jul 03, 2006 3:55 am

To solve many ordering issues, NHMA follows the order of the XML mapping schema; so it is not possible to change this order arbitrarily.

The next release of NHMA will come with a new attribute called "RawXml"; so you may use it as a work around to insert the ManyToOne before the Property.

vladimirak · **Joined:** Fri Jun 30, 2006 4:17 am **Posts:** 4

I don't understand this restriction. In nhibernate-mapping-2.0.xsd I see the following:

Code:

<xs:choice minOccurs="0" maxOccurs="unbounded">
  <xs:element ref="property"/>
  <xs:element ref="many-to-one"/>
  <xs:element ref="one-to-one"/>
  <xs:element ref="component"/>
  <xs:element ref="dynamic-component"/>
  <xs:element ref="any"/>
  <xs:element ref="map"/>
  <xs:element ref="set"/>
  <xs:element ref="list"/>
  <xs:element ref="bag"/>
  <xs:element ref="idbag"/>
  <xs:element ref="array"/>
  <xs:element ref="primitive-array"/>
</xs:choice>

It's a choice, not a sequence. Where is ordering that you mentioned?

KPixel · **Posted:** Tue Jul 04, 2006 11:24 am

NHMA follows the order of elements; even if the XSD allows them to come in any order.

The reason is that it solves many issues.
It would be possible to write the elements in any order, but it would make it impossible to map elements taking sub-elements... (collections and like)