collection of classes with collection of classes

Hello World,

Once again I'm in need for your help....

I've built a collection of my own class which also holds a collection with onather class.
so i can do something like this :
colalfa(2).colbeta(3).text = "test"

from a db I read a lot of records with data like this:
alfanr betanr strtext
1 4 aaa
56 78 bbb
46 2 ccc

I want to add this data to my collection.

something like:
colalfa(alfanr).colbeta(betanr).text=strtext

how can i check if the colalfa(alfanr).colbeta(betanr) is already created ???
because if it does not exist yet i have to add it to my collection.


Greetinx,

Don

You can simply try to access it. If it doesn't exist you will get a trappable error.

Code:

---

'this code assumes you've read the db
'and that the result is in a RecordSet object
'called rs
On Error Resume Next
colalfa(rs!alfanr).colbeta(rs!betanr).Text = rs!strtext
If Err Then
    'the item doesn't exist so create it here
End If

---

Good luck!

Without errorhandling, you can try to compare with IS

Code:

---

IF colalfa(rs!alfanr).colbeta(rs!betanr) Is nothing then
'does not exist
end if

---

kedaman's solution:

when trying this error occurs in the following code:

Code:

---

Public Property Get Item(vntIndexKey As Variant) As colbeta
    'used when referencing an element in the collection
    'vntIndexKey contains either the Index or Key to the collection,
    'this is why it is declared as a Variant
    'Syntax: Set foo = x.Item(xyz) or Set foo = x.Item(5)
  Set Item = mCol(vntIndexKey)
End Property

---

how should i handle this ???


[Edited by Kersey on 09-07-2000 at 05:25 AM]

No! You don't have to catch the error within the class.
VB will raise an error when you're trying to access an item that doesn't exist.

thanx
think YOUR solution will work just fine...

actually i was trying Kedaman's solution alredy but couldn't fix this error so if anyone would still reply ????....

Don

Quote:

---

Originally posted by Kersey
thanx
think YOUR solution will work just fine...

actually i was trying Kedaman's solution alredy but couldn't fix this error so if anyone would still reply ????....

Don

---

why wouldn't you be going for guru?

The problem is that Joacims solution resumes everytime an error occur, which is probably why the error didn't appear at all.

Now in the property get statement, put the set statement in the else part of a if statement comparing the reference with nothing again. ;)

so I'll check for an error in

Code:

---

Public Property Get Item(vntIndexKey As Variant) As colbeta
    'used when referencing an element in the collection
    'vntIndexKey contains either the Index or Key to the collection,
    'this is why it is declared as a Variant
    'Syntax: Set foo = x.Item(xyz) or Set foo = x.Item(5)
  Set Item = mCol(vntIndexKey)
End Property

---

and set it to nothing if the err occurs.

so the object = nothing

to a_silvy :

I'm already working as a professional VB-developper, all that counts on your CV (at the end of the month this equals some amount of money in your wallet) is your MSDN & other diploma's , project experience ( finish them WELL & in time).
Who on earth cares if you're a vb-world guru (with respect to them who have the time skill and knowledge to reach this)??? ( I don't have the time !!!!)
When your good you will have to prove it in real life,
where other skills or even more important than programming Vb.
This does not mean I'm only here to ask question get the answer a go my own way ( Cashing in others peoples solutions).
Instead for every question I ask i try to answer at least one person as good as possible.
Because Togheter we can make better app's than each of us alone !

You just use the same technique again:

Code:

---

if not mcol(vntindexkey) is nothing then
 set item=mcol(vntindexkey)
end if

---

the item will remain nothing if theres no reference

Dear Kedaman,

using following code (as suggested):

Code:

---

Public Property Get Item(vntIndexKey As Variant) As Gas
    'used when referencing an element in the collection
    'vntIndexKey contains either the Index or Key to the collection,
    'this is why it is declared as a Variant
    'Syntax: Set foo = x.Item(xyz) or Set foo = x.Item(5)
    If Not mCol(vntIndexKey) Is Nothing Then
        Set Item = mCol(vntIndexKey)
    End If
     
End Property

---

does generate following error

run-time error 5 : invalid procedure call or argument

at the line

Code:

---

If Not mCol(vntIndexKey) Is Nothing Then

---

because You cant use mcol(vntIndexKey) when vntIndexKey does not exist in the collection !!!!

So I think, I have to check for an error right here....

Unless someone else disagrees with me and supplies a solution for this

IT MIGHT BE YOU.....POST IT (please ?)


greetinx,


Don

You mean that you pass a key, instead of a index? eh, the error should be with block or variable not set, but i'm not sure, so anyway as it didn't work, you could use error trapping instead, to be sure use:
on local error resume next

shouldn't affect any error handling outside the class.
The property will still return an empty reference so you should use the is comparation method out there.

when passing a not existing index I get a subscript out of range !!!!

still testing da lot
so far this works fine:

Code:

---

Public Property Get Item(vntIndexKey As Variant) As Gas
    'used when referencing an element in the collection
    'vntIndexKey contains either the Index or Key to the collection,
    'this is why it is declared as a Variant
    'Syntax: Set foo = x.Item(xyz) or Set foo = x.Item(5)
    On Local Error Resume Next
        Set Item = mCol(vntIndexKey)
End Property

---

Thanks for your Contribution !!!
(especially : KeDaMaN & JoAcHiM A.)


Don.

That should avoid everything, you could use ubound, lbound, abs and int to avoid the SOOR error, but this time errorhandling wins the game :)