[英]Load collection with custom SQL in NHibernate
I'm pretty new to NHibernate. 我对NHibernate很新。 I understood the main concepts, but now I'm a bit stuck : I need to load a collection property using a slightly complicated SQL query.
我理解了主要概念,但现在我有点卡住:我需要使用稍微复杂的SQL查询加载集合属性。 Let me explain: I'm writing a code generator that generates classes from Oracle tables (using oracle TAB and COL views).
让我解释一下:我正在编写一个代码生成器,它从Oracle表生成类(使用oracle TAB和COL视图)。 So basically, I have two classes, Table and Column, described like this:
所以基本上,我有两个类,表和列,描述如下:
public class Table
{
public virtual String Name { get; set; }
public virtual ISet<Column> Columns { get; set; }
public virtual ISet<Column> PrimaryKeys { get; set; }
}
public class Column
{
public virtual Table Table { get; set; }
public virtual String TableName { get; set; }
public virtual String Name { get; set; }
public virtual String Type{ get; set; }
public override bool Equals(object obj)
{
Column c = obj as Column;
if (obj == null)
return false;
return c.Table == Table && c.Name == Name;
}
public override int GetHashCode()
{
return (this.TableName.GetHashCode() + Name.GetHashCode()).GetHashCode();
}
}
The mapping xml files are straightforward: 映射xml文件很简单:
Table.hbm.xml : Table.hbm.xml:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="ModelGenerator" namespace="ModelGenerator.Models">
<class name="Table" table="TAB">
<id name="Name" column="TNAME"></id>
<set name="Columns" order-by="COLNO">
<key>
<column name="TNAME"></column>
</key>
<one-to-many class="Column"></one-to-many>
</set>
</class>
</hibernate-mapping>
Column.hbm.xml : Column.hbm.xml:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="ModelGenerator" namespace="ModelGenerator.Models">
<class name="Column" table="COL">
<composite-id>
<key-property name="TableName" column="TNAME"></key-property>
<key-property name="Name" column="CNAME"></key-property>
</composite-id>
<property name="Type" column="COLTYPE"></property>
<many-to-one name="Table">
<column name="TNAME"></column>
</many-to-one>
</class>
</hibernate-mapping>
Now I'd like to add in the class Table a collection that contains the primary keys. 现在我想在类Table中添加一个包含主键的集合。 I can get the primary key columns with the following query :
我可以使用以下查询获取主键列:
SELECT col.tname, col.cname, col.coltype
FROM all_constraints cons, all_cons_columns cons_cols, col
WHERE cons_cols.table_name = :MY_TABLE
and cons_cols.OWNER = :MY_ORACLE_USER
AND cons.constraint_type = 'P'
AND cons.constraint_name = cons_cols.constraint_name
AND cons.owner = cons_cols.owner
and col.tname = cons_cols.table_name
and col.cname = cons_cols.column_name
ORDER BY cons_cols.table_name, cons_cols.position
The results of this query could be mapped with my Column class. 可以使用我的Column类映射此查询的结果。 Ideally, my Table class would be now :
理想情况下,我的Table类现在是:
public class Table
{
public virtual String Name { get; set; }
public virtual ISet<Column> Columns { get; set; }
public virtual ISet<Column> PrimaryKeys { get; set; }
}
My problem is that I can't see how to declare this SQL query in my Table.hbm.xml file. 我的问题是我无法看到如何在Table.hbm.xml文件中声明此SQL查询。 I saw the <sql-query> and <load-collection> elements in the documentation but I can't make it work as I want...
我在文档中看到了<sql-query>和<load-collection>元素,但我无法按照我的意愿使其工作...
Does anyone know how to achieve this? 有谁知道如何实现这一目标?
Many thanks, 非常感谢,
Nico 尼科
Well, finally I found my problem :) 好吧,最后我发现了我的问题:)
It was mainly caused by the <sql-query> element that I put inside the <class> element. 它主要是由我放在<class>元素中的<sql-query>元素引起的。 NHibernate was unable to find it there.
NHibernate无法在那里找到它。
So I kept the Table.cs as is, and now my Table.hbm.xml looks is the following: 所以我保持Table.cs不变,现在我的Table.hbm.xml看起来如下:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="ModelGenerator" namespace="ModelGenerator.Models">
<class name="Table" table="TAB">
<id name="Name" column="TNAME"></id>
<set name="Columns" order-by="COLNO">
<key>
<column name="TNAME"></column>
</key>
<one-to-many class="Column"></one-to-many>
</set>
<set name="PrimaryKeys">
<key>
<column name="TNAME"></column>
</key>
<one-to-many class="Column"/>
<loader query-ref="primarykeys"/>
</set>
</class>
<sql-query name="primarykeys">
<load-collection alias="col" role="Table.PrimaryKeys"/>
SELECT col.tname, col.colno, col.cname, col.coltype, col.width, col.scale, col.precision, col.nulls, col.defaultval, col.character_set_name
FROM all_constraints cons, all_cons_columns cons_cols, col
WHERE cons_cols.table_name = ?
and cons_cols.OWNER = 'MY_ORACLE_USER'
AND cons.constraint_type = 'P'
AND cons.constraint_name = cons_cols.constraint_name
AND cons.owner = cons_cols.owner
and col.tname = cons_cols.table_name
and col.cname = cons_cols.column_name
ORDER BY cons_cols.table_name, cons_cols.position
</sql-query>
</hibernate-mapping>
It works! 有用! I hope it can help anyone.
我希望它可以帮助任何人。
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