But as the proxy is a subclass of Employee, this.getBoss() will get
intercepted by the proxy method handler which will load the boss
immediately before hasMoney() is invoked on it. So I see no need to
load it at the point of askARase() invocation.
Regards
--
Carlos
On Wed, Dec 16, 2009 at 4:45 PM, Poitras Christian
<christian.poit...@ircm.qc.ca> wrote:
> Hi Bardamu,
>
> I think it was not clear enough due to the lack of Proxy explanation.
> If I have an employee and I call getBoss() on it, it has to load the boss
> property. But what if I call a method like this in employee?
> public boolean askARase() {
> if (this.getBoss().hasMoney()) {
> return true;
> } else {
> return false;
> }
> }
>
> Then, I hope the boss property is loaded before hasMoney() is called on it.
> The boss property itself is a proxy that can be defined as <E extends
> Employee>, but what is E? Since iBATIS does not know for sure, I has to call
> the select to get the right type for boss as soon as any method on Employee
> is called.
>
> Christian
>
>
> -----Original Message-----
> From: Carlos Pita [mailto:carlosjosep...@gmail.com]
> Sent: Wednesday, December 16, 2009 12:16 PM
> To: user-java@ibatis.apache.org
> Subject: Re: Lazy loading differences between ibatis 2 and 3
>
> Hi Christian,
>
> I understand your point but I don't get its relation to my question at all.
> Continuing your example, I would ask why employee.getName() will prematurely
> load the boss. A priori, I would expect the proxy to be smarter and only
> trigger the loading of boss if getBoss() was effectively called.
>
> Regards
> --
> Bardamu
>
> On Wed, Dec 16, 2009 at 3:09 PM, Poitras Christian
> <christian.poit...@ircm.qc.ca> wrote:
>> Hi,
>>
>> The major problem that was present in iBATIS 2 was that lazy loaded class
>> where not always of the right type.
>> For exemple, if I have multiple subclasses of a class.
>> Person
>> Employee inherits Person
>> Director inherits Employee
>>
>> If I have an object Employee with a method getBoss() that returns an
>> Employee (lazy loaded), I expect that sometimes it will be a director.
>> In iBATIS 2, testing (employee.getBoss() instanceof Director) will always be
>> false. This problem is due to the fact that iBATIS does not know the real
>> class of the boss property and creates a Proxy of Employee.
>> In iBATIS 3, testing (employee.getBoss() instanceof Director) will be true
>> if the employee's boss is a Director. To know the real type, the statement
>> must be executed.
>>
>> Christian
>>
>>
>> -----Original Message-----
>> From: Carlos Pita [mailto:carlosjosep...@gmail.com]
>> Sent: Wednesday, December 16, 2009 11:45 AM
>> To: user-java@ibatis.apache.org
>> Subject: Lazy loading differences between ibatis 2 and 3
>>
>> Hi all,
>>
>> I've the following sqlmap for ibatis 2. Suppose ibatis has its
>> lazy-loading feature enabled and I obtain a user U by means of
>> findUserById. Then I call U.getEmail() and findMemberById is not
>> executed. That's fine, one wouldn't expect the associated member to be
>> loaded until there is a real need for it. Of course, if then I call
>> U.getMember().getDescription() findMemberById does execute its select, in
>> due time. That said, for ibatis 3 the same example executes findMemberById
>> as soon as U.getEmail() is invoked, loading the member before time. That's
>> not surprising if one inspects the code of ResultObjectProxy (relevant parts
>> copied below). Is this intended to work the way it does or is it a bug?
>>
>> <sqlMap namespace="User">
>>
>> <resultMap id="userMap" class="User">
>> <result property="email" column="email"/>
>> <result property="member" column="member_id"
>> select="findMemberById"/>
>> </resultMap>
>>
>> <resultMap id="memberMap" class="Member">
>> <result property="description" column="description"/>
>> </resultMap>
>>
>> <select id="findUserById" resultMap="userMap">
>> select * from qpoint_user where id = #id#
>> </select>
>>
>> <select id="findMemberById" resultMap="memberMap">
>> select * from cpp_member where member_id = #id#
>> </select>
>>
>> </sqlMap>
>>
>>
>> public class ResultObjectProxy {
>>
>> public Object invoke(Object o, Method method, Object[] args) throws
>> Throwable {
>> try {
>> if (!Object.class.equals(method.getDeclaringClass()) &&
>> PropertyNamer.isGetter(method.getName())) {
>> lazyLoader.loadAll(); <-- this loads all asociations for
>> every getter invoked on this proxy
>> }
>> return method.invoke(target, args);
>> } catch (Throwable t) {
>> throw ExceptionUtil.unwrapThrowable(t);
>> }
>> }
>> }
>>
>> Regards
>> --
>> Bardamu
>>
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