Re: WOPopUpButton
Re: WOPopUpButton
- Subject: Re: WOPopUpButton
- From: Ray Kiddy <email@hidden>
- Date: Sun, 24 Jun 2007 18:13:46 -0700
On Jun 21, 2007, at 11:15 AM, Sigurður E. Vilhelmsson wrote:
Hi all,
I'm a relative newbie to the Java and WebObjects world (actually the
world of programming in general), and have been playing around with
Eclipse and WOLips, using the tutorials on the objectstyle wiki and
the excellent new tutorial by Janine Sisk. Now I'm starting to
experiment on my own. I've gone through most of Apple's materials and
Googled my brains out, but a WOPopUpButton has me stomped.
I have a model with two tables, Course and Course_description. I have
a to-one relationship in the Course table, called course_descriptions,
with a source attribute course_descriptionID in table Course, and a
destination attribute course_descriptionID in table
Course_description.
I am trying to build a form for entering new Courses, where I want to
include a WOPopUpButton where the user can select from the "name"
attributes in table Course_description to populate the
course_descriptionID in table Course.
I figure I need to build an NSArray and populate it with the values
from the Course_description table and then use that to populate the
course_descriptionID in the Course table, but exactly how to do that
is just out of my reach.
Anyone up for a little WO 101?
Best regards,
Sigurdur
Did you ever get an answer to any of your original question? Not the
question involving typography?
Why is it that Course and CourseDescription are separate entities.
Would it not be that a Course is an entity and that entity has
attributes, such as "description"?
Does the course description change every time the course is offered?
Even though it is the same course? This seems odd.
(Just FYI, some of the WO tools complain about actually using
"description" as an attribute. This is a holdover from the old ObjC
days, where 'description' was a method that everyone inherited (if I
recall correctly) from NSObject. So, you might want to come up with
another name, like "desc".)
Usually, when this has been done before, people have a schema like:
Course:
name
desc
numCredits
>> CoursesOffered
CourseOffered:
startDate
endDate
location
>> Professor(s)
>> Students
> Course
Professor:
name
contactInfo
>> CourseOffered
Student:
name
>> CourseOffered
etc...
For extra credit, the Professor and the Student can actually come
from the same table, a People table. Then "Professor" and "Student"
entities can be defined via single-table entity inheritance.
The significant thing to realize about the WOPopupButton is that you
are selecting an object from a list of objects. The "displayName"
binding can decide how the object gets displayed, but only that. The
name of something is not usually a stand-alone thing. It is usually
an attribute of the object.
So, you build an array of the objects from which one should choose,
bound to "list". Then have an ivar for the list to iterate with,
bound to item. Then you have an ivar for the object that gets selected.
Google searches on WOPopupButton may show you examples. I always get
confused about whether to use "selected" or "selectedObject" for the
chosen thing. I just look it up and see that for a session-based app,
one should use "selection". Direct actions are for later.
- ray
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| References: | |
| | >WOPopUpButton (From: "Sigurður E. Vilhelmsson" <email@hidden>) |