Re: Writing a beginners tutorial, some D2W questions on Webassistant and ERAtachment
Re: Writing a beginners tutorial, some D2W questions on Webassistant and ERAtachment
- Subject: Re: Writing a beginners tutorial, some D2W questions on Webassistant and ERAtachment
- From: Johan Henselmans <email@hidden>
- Date: Sat, 19 Jan 2008 23:11:38 +0100
On 19 jan 2008, at 22:01, Guido Neitzer wrote:
On 19.01.2008, at 13:47, Johan Henselmans wrote:
The application would be a shop, with a D2W backend for the
products (with ERAttachment for the product-pictures), fulfilment
(some kind of app that could run in an ipod touch) and some
statistics app that would make use of displaygroups and SVG.
The only thing I can say about that: Don't make beginners miserable
with D2W. To use D2W and to be able to customize an application to
your needs, you need a way more deep understanding of WebObjects
than a tutorial can provide.
I planned it to only use it for the backend application to add
products and product categories, and uploading pictures of the
products. That's it. just give a feel of DirectToWeb. Explain the rule
system, and how to customize a part. The other stuff would be normal
WebObjects stuff. Sorry if my phrasing was not precise. The
fulfillment and the statistics would make use of the other tools.
And personally I think that your tutorial is way overfilled with
stuff. Beginners can take only so much in a tutorial. If you don't
want to write a 600 page book, you will not be able to bring all
that stuff in, add diagrams and screenshots and explain everything a
beginner needs to know. And believe me: I know what I'm talking
about as I'm facing the same problem.
That tutorial is nearly finished, so I am starting with the
DirectToWeb part. On Leopard, the DirectToWeb Assistant does not
work.
If you really want to use D2W - stay away from that rule-breaking,
stupid assistant. Nobody will ever understand D2W in the necessary
way with seeing and writing actual rules. In my opinion that
assistant was a bad idea from the very beginning. And I do a lot of
D2W.
If you do a lot of D2W, you know the rulesystem, you'll have your
working examples and you'll know all the rules.
Now suppose you are a beginner. You are starting with a Direct2Web
app, which is supposed to be better than sliced bread, especially if
you are using Wonder. So he starts a WonderD2W Application in WOLips,
has an EOModel (a shop with a product, productcategory and an n:m
relation), and opens the app. He logs in, and adds some products. It
works. Nice. Than he adds a few product categories. Now he wants to
link the products and productcategories. Instead of seeing the
productcategories in a product he sees something called
com.webobjects.eocontrol._EOCheapCopyMutableArray[b2f057] , whatever
that may mean. A little disappointed, the developer tries to edit the
product. But where? By default he can only inspect them, and not edit
them. Why is that?
How is he going to change that? Very simple, the Direct2Web tutorial
says. You are too inexperienced. First learn all the intricacies.
Then, fire up the rule editor. Then add a rule: it is very simple,
just add
{
rules = (
{
author = 100;
class = "com.webobjects.directtoweb.Rule";
lhs = {
class = "com.webobjects.eocontrol.EOKeyValueQualifier";
key = task;
selectorName = isEqualTo;
value = list;
};
rhs = {
class = "com.webobjects.directtoweb.Assignment";
keyPath = isEntityEditable;
value = true;
};
}
);
}
See: it's that simple.
Now start reading again about all the tasks, of which you take one
then take one from the 17 right hand side classes and the 300
something right hand side keys, and some right hand side value. Very
Simple. You just have to know all the combinations, and you'll be fine.
All the experienced Direct2Web developers have started this way.
His promise to whip up quick interface for the backend so he could
concentrate on the frontend can be thrown out of the window.
Oh well. On to Ruby On Rails, or sticking to PHP, or WebObjects
without D2W.
D2W has changed from a gentle introduction to webobjects and a quick
interfacebuilder to the steepest learning cliff...
(and no, Rule Editor is not an easy and quick tool if you're a
beginner and you don't want to shoot yourself in the foot)
Again: D2W is WAY OVER THE HEAD for a beginner to be happy with. It
is a very cool technology demonstration and it is an incredibly
powerful tool for WO developers who really understand WO but it is
also something where beginners will hit the wall with the first
customization they want to make.
cug
D2W without a proper assistant is. So how is one suppose to learn D2W?
How did you learn it?
I am not going to demonstrate all the intricacies of a d2w app: just
standard interface, a login routine, and a file-upload for a picture.
That's it, for now. It is meant to be a tutorial for beginners, to
give them a feeling of how it works, and give them a feeling of one
should go about. And then he/she can go on and find out that for the
really nifty stuff, he should get a training at the Big Nerd Ranch ;-)
--
Real-World WebObjects class at the Big Nerd Ranch
March 2008, Frankfurt, Germany
http://www.bignerdranch.com/classes/webobjects.shtml
Regards,
Johan Henselmans
http://www.netsense.nl
Tel: +31-20-6267538
Fax: +31-20-6273852
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