RE: Reactor For CF query.setMaxRows()

[Doug Hughes]

FYI - the new Iterator functionality will make pagination quite easy.  See
the attached message.

Doug

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chris
Blackwell
Sent: Friday, February 10, 2006 1:07 PM
To: reactor@doughughes.net
Subject: Reactor For CF query.setMaxRows()

>From looking at the query debug output it looks like setMaxRows()
function sets the maxrows attribute of the <cfquery> tag, as I don't see
LIMIT in the sql.

When displaying large paginated recordsets i like to use the power of
MySQL's LIMIT clause and provide an offset so I only get back the rows I
will be displaying, like...

SELECT * FROM tblName
LIMIT 10 OFFSET 20

I don't know whether this works in other DB's.

So is there anyway to implement this in Reactor?  Seems to me that the
query object would need a setOffset() method, but that might break in
dbs other than mysql.

If this is "application functionality that is needed by the developer
that may seem, to the developer, like it should be a job of the
framework itself" then feel free to shoot me down ;)  At the moment I'm
still trying to get my head around Reactor so working out where it
should end and my application starts is a little blurry atm.

Chris




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Yesterday I introduced the Iterator object.  The purpose of the Iterator object is to essentially make it pretty easy to work with sets of records.   Today I added four arguments that add a lot of power.  If you have, for example, an Iterator for a user, you can now  pass from and count arguments to getArray and getQuery.  What’s this mean?  It means pagination I a piece of cake.  Here’s a sample:   <!--- get the first ten records from the Iterator -à <cfdump var=”#UserIterator.getQuery(1, 10#” />   <!--- get the second ten records as an array -à <cfdump var=”#UserIterator.getArray(2, 10)#” />   Why is this particularly cool?  Well, the Iterator lets you sort and filter the data as you need.  When you actually request data it’s cached in the object’s variables scope.  So, let’s say you’ve got 1000 users in your database.  Creating the Iterator doesn’t do anything with them.  However, calling getQuery() will load them and cache them.  From that point forward you’re working with the dataset in memory.  Thus, getQuery(1, 10) just slices those records out of the variables scope.  Same with getArray.  If you have your Iterator in a persistent scope then you’re not going to have to run any additional queries.  (Sorting and filtering reset the query and it’s re-run.)   This isn’t as good as only getting the specific rows you want from the DB as needed, but it’s as good as I can do, given the differences in implementations between database servers.   Oh, that said, wouldn’t it be cool if you could just get an Iterator for any given object easily?  Well, you can.  Now the reactorFactor has a createIterator() method that works just like the other create methods.  The only difference is that it doesn’t generate anything.  (Ok, it will, if your records don’t exist.)   Doug

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