On Apr 23, 2008, at 8:02 PM, Jeff Schmitz wrote:
As I get into full swing of using EO's, I'm seeing one place that I
know is going to bite me, and that is indexing into the array
returned by the parameterless function that returns "many"
relationships and assuming a certain order.
Don't. The order is undefined. It is really a set (unordered
collection), not a vector. That is just the way it is.
I'd almost rather not even have that function, at least by default,
so that it would force me to always either qualify or sort the
results. e.g.
Doing this (assuming the array is sorted appropriately for winIndex:
WinAnalysis currWA =
currGame.winAnalyses().objectAtIndex(winIndex);
Very dodgy. Expect painful debugging.
Instead of this:
EOQualifier winQual = WinAnalysis.PLACE.eq(winIndex + 1);
WinAnalysis currWA = currGame.winAnalyses(winQual).lastObject();
Or am I missing something? I'm just really scared this is going to
bite me, and cost me LOTS of debugging time.
Usually you don't care about position within a to-many. If you do,
you can very carefully carry around a sorted version. BUT it can be
very tricky to keep this in sync so I do no recommend it. You could
also sort / search / qualify everywhere you use it, but that is
fragile and prone to being forgotten. Your best bet might be to make
an API and use that in your processing. For example, add this to Game:
public WinAnalysis analysisAtPlace(int place) {
EOQualifier winQual = WinAnalysis.PLACE.eq(place);
return (WinAnalysis)winAnalyses(winQual).lastObject();
}
Then you don't need to worry about 0 based vs 1 based, just use
aGame.analysisAtPlace(3); or maybe a better name is
aGame.analysisOfRound(3);
Hide the implementation. Code to the interface.
Chuck
--
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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