Using Relationships & Display Groups
Using Relationships & Display Groups
- Subject: Using Relationships & Display Groups
- From: David Griffith <email@hidden>
- Date: Fri, 20 Feb 2004 13:10:13 +0100
Hi,
This is a newbie question I guess, but honestly it is so hard to find any
step-by-step useful information for the WebObjects beginner. I have been
using RAD tools for years and am having real difficulty getting into the WO
way of doing things.
So, the first question is:
I have for example, 2 tables. Country & Zone.
Country <<--> Zone
So Country can ask for it9s Zone and Zone can ask for the Countries in that
zone. This makes sense in a logical way.
Country contains countryID (primary key) and countryZoneID (foreign key for
zone).
Zone contains zoneID (primary key).
What I want to know is, when using the
country.addObjectToBothSidesOfRelationshipWithKey(zone, 3zone2) - does this
effectively set the foreign key of the country to hold the primary key of
the zone?
Let me describe the scenario in a little more detail:
I have a WOComponent that uses a display group (combined with a PopUpButton
rather than a WORepetition) which displays all the existing Zones and
permits me to add new ones. This works fine.
Then, I have another WOComponent for adding and editing countries. Each
country must have a Zone. So I have a display group for listing the
countries, from which I can select a country and edit it etc.
When adding a country, I obviously need to specify the zone it belongs to.
For this, in the data part of the page, I have another PopUpButton which
uses another display group to list all the zones available. I want to enter
the country name for a new country, then select the relevant zone from the
Zones pop up. This will submit the zoneForm and allow the selection to be
acknowledged.
So, at this stage I have a new country name entered, and I have selected a
zone from the list of zones. I know want to relate9 them when the new
country is saved. Basically, I am getting an error each time stating that
the countryZoneID (the foreign key for the zone in the country table) is
null and therefore cannot be saved. I have tried
country.addObjectToBothSidesOfRelationship(selectedZone, 3zone2) but it
seems to make no difference.
I hope someone has some idea what I am talking about and can help! If I can
get a clearer understanding of how this works it will open things up
tremendously for me!
Kind regards,
David.
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