Vadim,
One other way would be to pass parameters that require logic in
using a map. I know there are pros and cons to using a map, but you
can send this from your service layer where you have the rest of your
business logic (from which you're probably calling your DAO anyway).
It does lead to DAO's where you have a single parameter of a map and
consequently have to look at the sql to determine the parameters, but
depending on implementation. The advantage is that you don't have
logic in your bean. Another advantage is that you're not passing half
filled objects around. Expecting such objects doesn't lead to any
tighter coupling than you'd find with a map anyway.
The other thing to keep in mind is that you can nest logical
expressions in your map. For 2 - 3 element "and" or "or" logic, it
shouldn't take many evaluations to cover all possible scenarios.
Obivously, this is something you would want to minimize for readability
and debugging ease.
Diran
Vadim Grinshpun wrote:
True, that
is a way to get around this issue (and it is what I'm doing now).
While I agree that logic is more readable when written in Java, I'd
also like to point out that the main advantage of using the data mapper
(at least for me) is to avoid having anything query-related in the
code. This kind of logic has no use outside of a particular database
definition/query, and would be good to keep away from the bean that
otherwise acts only as a container for data...
The bottom line is I'll be a happier man if the iBATIS folks do wind up
adding something that allows this to be done :)
(and I appreciate that this is not a trivial task, just expressing a
hope :)
-Vadim
Jeff Butler wrote:
There's nothing in iBATIS that will do this.
I've done something similar in the past by adding a getter to the
parameter object and coding the logic in the getter method. Like this:
public boolean isComplexCondition {
...some complex decision
}
Then coding an <isEqual property="complexCondition" value="true">
in the SQL Map.
I ended up liking this better anyway - I think the logic is easier to
understand when written in Java.
Jeff Butler
On 6/28/06, *Vadim Grinshpun* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Er... Thanks, but either you misread my example, or I completely
do not
understand what you mean.
The example I gave uses a large chunk of iBATIS-like *pseudocode*
(there is no 'if' tag and no 'or' tag!), and thus cannot work as
is.
I've looked through the Dev Guide ( version that was in SVN as of
6/20),
but so far was unable to find anything that would allow for this
kind of
functionality. (effectively, what I want is to have a *SINGLE*
iBATIS
conditional that would test multiple properties and OR the
results).
Could you take another look at it, please, or explain in more
detail?
Thanks!
-Vadim
Niels Beekman wrote:
> Yes, that should work out just fine. See the Developer Guide
for
some
> examples...
>
> -----Original Message-----
> From: Vadim Grinshpun [mailto: [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>]
> Sent: woensdag 28 juni 2006 20:58
> To: [email protected]
<mailto:[email protected]>
> Subject: flexible queries?
>
> Hi everyone,
>
> Suppose I have a query where I want a join to be performed
only
if *one
> or more* of a set of parameters are present.
> Is there a way in SqlMaps to do something like this? (below is
an
> example snippet of what I'd like to do, using some pseudocode
in the
> first <dynamic> section):
>
> SELECT * FROM
> table_foo f, table_bar b
> <dynamic> <!-- if any of the params in the
conditional are
defined,
> add one more table to join -->
> <if>
> <or>
> <isEqual property="X.defined" compareValue="true"
/>
> <isEqual property=" X.defined"
compareValue="true" />
> </or>
> <then>, table_baz z</then>
> </if>
> </dynamic>
> WHERE f.field = b.field
> <dynamic>
> <isEqual property="X.defined" compareValue="true"
prepend="AND"
> >z.x_field > #X.value#</isEqual>
> <isEqual property=" Y.defined" compareValue="true"
prepend="AND"
> >z.y_field = #Y.value#</isEqual>
> </dynamic>
>
>
> Thanks,
> --Vadim
>
>
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