具有相同 ID 键字段的多对多 [英] Many-to-many with Same Id Key fields

问题描述

如何在 nHibernate 中以多对一和一对多的方式连接两个表.它们都具有与键列相同的PLAN_ID".我的数据库结构预先存在.

下面是我使用的映射和我得到的错误:

表:计划(一个)

PLAN_ID <-- PRIMARY KEY开始日期CHECK_CHAR...

表格:PLANN_DOCUMENT(到许多)

PLAN_ID <-- PRIMARY KEYDOC_ID <-- DOCUMENT 表的 IDDOC_NAMEDOC_TYPE

计划类:

public virtual... PlanId, StartDate, CheckChar, PlanStatus,公共虚拟 ISetDocsysHoldingDocs { 获取；放;}公共虚拟 DocsysHoldingDoc DocsysHoldingDoc { 获取；放;}

计划文档类:

public virtual...PlanId, DocId, DocName, DocType公共虚拟计划 PlannItem { get;放;}

规划 HBM XML

<id name="PlanId" column="PLAN_ID"<generator class="assigned"/></id><property name="StartDate" column="START_DATE"/><属性名称=CHECK_CHAR"列=CHECK_CHAR"/>...<set name="PlannDocument" table="PLANN_DOCUMNET"><key column="PLAN_ID"></key>//<<键在加入表中，但也在这个表中<一对多类="DocsysHoldingDoc"/></set></class>

计划文档 HBM XML

<id name="PlanId" column="PLAN_ID" type="int"><generator class="assigned"/></id><属性名称=DocId"列=DOC_ID"/><property name="DocName" column="DOC_NAME"/><property name="DocType" column="DOC_TYPE"/><many-to-one name="Plann" column="PLAN_ID"></many-to-one></class>

<块引用>

错误:NHibernate.MappingException: '无法为类 <>.PlannDocument 构建插入语句:添加类的 Id 时发生失败'

ArgumentException:已在此 SQL 构建器中添加了PLAN_ID"列 参数名称:columnName

我在这里做错了吗?

解决方案

根据您的评论(在已删除的答案下)，两个表中的主键列的名称相同 - 即 PLAN_ID.您想基于多对一关系连接这两个表.

这里的问题是相同的列名(来自两个不同的表)在映射中被添加了两次.

这就是错误的原因:

<块引用>

ERROR: NHibernate.MappingException: '无法为类 <>.PlannDocument 构建插入语句:添加类的 Id 时发生故障'

ArgumentException:列 'PLAN_ID' 已添加到此 SQL 构建器参数名称:columnName

在 PlannDocument HBM 中，列名 PLAN_ID 在创建 id 时首先使用，如下所示:

然后，再次创建多对一关系如下:

这会导致列名冲突.

我能想到的解决方案是将列名更改为其他表延迟的内容.此外，相应地修改类和映射.

我知道这不可能在所有情况下都成为解决方案.

How do I join two tables as many-to-one and one-to-many in nHibernate. They both have the same 'PLAN_ID' as the key column. My Database structures pre-existing.

Below is the mapping I am using and the error I'm getting:

Table: PLANN (one)

PLAN_ID  <-- PRIMARY KEY
START_DATE
CHECK_CHAR
...

Table: PLANN_DOCUMENT (to many)

PLAN_ID <-- PRIMARY KEY
DOC_ID <-- ID to a DOCUMENT table
DOC_NAME
DOC_TYPE

Plann class:

public virtual... PlanId, StartDate, CheckChar, PlanStatus,
public virtual ISet<DocsysHoldingDoc> DocsysHoldingDocs { get; set; }
public virtual DocsysHoldingDoc DocsysHoldingDoc { get; set; }

PlannDocument Class:

public virtual...PlanId, DocId, DocName, DocType
public virtual Plann PlannItem { get; set; }

Plann HBM XML

<class name="Plann" abstract="true" table="PLANN">
    <id name="PlanId" column="PLAN_ID"
        <generator class="assigned"/>
    </id>
    <property name="StartDate" column="START_DATE" /> 
    <property name="CHECK_CHAR" column="CHECK_CHAR" /> 
    ...

    <set name="PlannDocument" table="PLANN_DOCUMNET">
        <key column="PLAN_ID"></key> //<<KEY IN JOINING TABLE BUT ALSO ID IN THIS TABLE
        <one-to-many class="DocsysHoldingDoc"/>
     </set>
</class>

PlannDocument HBM XML

<class name="PlannDocument" abstract="true" table="PLANN_DOCUMNET">
    <id name="PlanId" column="PLAN_ID"  type = "int">
        <generator class="assigned"/>
    </id>
    <property name="DocId" column="DOC_ID" />
    <property name="DocName" column="DOC_NAME" />
    <property name="DocType" column="DOC_TYPE" />

    <many-to-one name="Plann" column="PLAN_ID"></many-to-one>

</class>

ERROR: NHibernate.MappingException: 'Unable to build the insert statement for class <>.PlannDocument: a failure occurred when adding the Id of the class'

ArgumentException: The column 'PLAN_ID' has already been added in this SQL builder Parameter name: columnName

Am I doing something wrong here?

解决方案

Based on your comments (under deleted answer), name of primary key column in both the tables is same - i.e. PLAN_ID. You want to join these two tables based on many-to-one relation.

The problem here is that the same column name (from two different tables) is being added twice in the mapping.

That is why the error:

ERROR: NHibernate.MappingException: 'Unable to build the insert statement for class <>.PlannDocument: a failure occured when adding the Id of the class'

ArgumentException: The column 'PLAN_ID' has already been added in this SQL builder Parameter name: columnName

In PlannDocument HBM, column name PLAN_ID is first used while creating id as below:

<id name="PlanId" column="PLAN_ID"  type = "int">

and then, again while creating many-to-one relation as below:

<many-to-one name="Plann" column="PLAN_ID"></many-to-one>

This is causing conflict of column name.

The solution I can think is to change the column name to something defer from the other table. Also, modify the classes and mappings accordingly.

I understand that this cannot be the solution every time and in all the conditions.

这篇关于具有相同 ID 键字段的多对多的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！