[jira] Commented: (IBATIS-231) Grougby for 1:1 relationship

["Sven Boden (JIRA)" <ib...@incubator.apache.org>]

    [ http://issues.apache.org/jira/browse/IBATIS-231?page=comments#action_12359924 ] 

Sven Boden commented on IBATIS-231:
-----------------------------------

I'm pretty sure this is a non-issue... Why would you use "group by" for a guaranteed 1:1 relationship. You can look at the attachment in JIRA-227 to see an example of 1:1 containment relationship without using "group by".

The reason for the List in "group by" is that it's not sure your relationship is 1:1. If more than 1 row would satisfy the "group by" for 1 parent object you need a List to store the children.

Unless countered this JIRA can be closed as "invalid".

Regards,
Sven


> Grougby for 1:1 relationship
> ----------------------------
>
>          Key: IBATIS-231
>          URL: http://issues.apache.org/jira/browse/IBATIS-231
>      Project: iBatis for Java
>         Type: Wish
>   Components: SQL Maps
>  Environment: Windows
>     Reporter: Leo Tu

>
> I have two classes, one is Parent(master) another is Child(Detail), but they are 1:1 relationship,
> The question is that in child class contains just one parent object, but i must use List for getter/setter elsewise
> has problem, why ?
> ===================================================
> // parent
> public class CustGroup {
>  ...
> }
> // child
> public class Cust {
>    ...
>  private CustGroup custGroup; // 1:1
>   ...
>   public void setCustGroupjava.util.List custGroupList) { ... } //  why it must be List data type ?
>   public java.util.List getCustGroup()  { ... } //  why it must be List data type ?
>   ...
> }
> <resultMap id="CustGroup-result" class="CustGroup">
>    ...
> </resultMap>
> <resultMap id="CUST-result" class="Cust">
>    ...   
>      <result property="custGroup" resultMap="CUST_GROUP"/> <!-- 1:1 -->
> </resultMap>
> ===================================================
> 1:1, but groupby must use List for getter/setter, 
> Can't  use 
>   public void setCustGroup(CustGroup custGroup) { ... } //  I hope  can use this methd
>   public CustGroup getCustGroup()  { ... }  //  I hope  can use this methd
> Best Regards,
> Leo

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