Re[2]: setting values
Re[2]: setting values
- Subject: Re[2]: setting values
- From: "A. Uchida" <email@hidden>
- Date: Thu, 20 Feb 2003 21:22:42 GMT
Dear Art Isbell,
Thanks indeed for your kind advices.
I will go back to learn Java language again and will try improve
my knowledge and skill.
Thanks again.
regards,
A. Uchida
Reply for "Re: setting values" written by Art Isbell at Wed, 19 Feb 2003 14:01:50 -1000
>On Wednesday, February 19, 2003, at 12:40 PM, A. Uchida wrote:
>
>> MacOS 10.1.5 & WO5.0
>
> If possible, upgrade to WO 5.1.3 for the most stable WO version that
>runs under OS X 10.1.
>
>> What I am trying to do in WO application is
>> 1. Create a new record in an entityA using display group insert().
>> 2. Save the new record in the entityA using saveChanges().
>> 3. Create a new record in an entityB using insert().
>> 4. set a value of an attribute of entityA to an attribute of the
>> entityB
>> 5. saveChanges() of entityB.
>>
>> I want to do the process 2 to 4 by an action on a WO component.
>>
>> What I did to set the value was to add
>> entityB.aData = entityA.aData;
>> in the action method in the java file.
>> Both entityA and B was produced as a key using the entities.
>> And it doesn't allow me to finish the build.
>
>> I think I had to use a method, something like "takeValueForKey".
>> But I don't know how to use it.
>
>> Question1 : what method can be used to set a value of an entity to a
>> field
>> of the other entity?
>
> EOF (Enterprise Objects Framework) is used by WO for database
>manipulation. An entity represents a database table in EOF. Each row
>in the table is represented by an object in EOF. Each object is an
>instance of a Java class associated with an entity in your eomodel. By
>default, the class is EOGenericRecord. If you need to implement custom
>business logic, you must associate a custom Java class with each entity
>in your eomodel and generate a Java class file for each custom Java
>class.
>
> NSKeyValueCoding methods may be used to set (takeValueForKey()) and
>get (valueForKey()) values regardless of whether you use
>EOGenericRecord or a custom Java class
>(http://developer.apple.com/techpubs/webobjects/Reference/API/com/
>webobjects/foundation/NSKeyValueCoding.html). Assuming aData is an
>attribute and not a relationship (relationship values can be set and
>gotten as well but using different methods):
>
>entityB.takeValueForKey(entityA.valueForKey("aData"), "aData");
>
> But the Java compiler is unable to check whether the string key
>argument of these methods, "aData", is valid, so the app may compile
>but throw an exception at runtime. To avoid this, use custom Java
>classes and their custom set and get methods:
>
>entityB.setAData(entityA.aData());
>
>> Question 2 : I am learning WO by myself and had read some books for WO
>> but
>> when I get lost like this case, what kind of documents, do you think,
>> are usefull?
>> I checked the documents of the WO: EOControl, Java reference for Java
>> etc.
>> But I don't think it is useful.
>
> I hope some other new WO users will respond.
>
> I think you must have a basic understanding of Java first. You don't
>need to know all of Java's features or most of the Java library API's
>for WO, but you should be able to read and understand Java code as well
>as write Java code at the level provided in
>/Developer/Examples/JavaWebObjects. There are many Java language books
>that can provide this level of Java skill. You should also be familiar
>with the Java API's in at least the java.lang, java.text, and java.util
>packages documented at http://java.sun.com/j2se/1.3/docs/api/.
>
> Then you need to become familiar with WO itself. You should become
>familiar with the API's in the com.webobjects.appserver,
>com.webobjects.eoaccess, com.webobjects.eocontrol, and
>com.webobjects.foundation packages documented at
>http://developer.apple.com/techpubs/webobjects/WebObjects_5.1/
>Reference/Javadoc/index.html.
>
> http://developer.apple.com/techpubs/webobjects/WebObjects_5.1/
>webobjects.html provides links to various documentation and tutorials
>that you should be familiar with including the development tools and
>environment.
>
> There's much to learn, but you don't have to learn everything to
>become productive.
>
>Art
>http://homepage.mac.com/aisbell/
>_______________________________________________
>webobjects-dev mailing list | email@hidden
>Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
>Do not post admin requests to the list. They will be ignored.
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.