I imagine this concept will be the same whether the sql statement is executed from the front end or the cursor is returned from a stored proc

I left joined credit cards to customers ( handling nulls and returning "NO CARD ON FILE") so there is a cardnumber field being returned in the cursor that I get with the stored proc

At debug time in me.customersbo1.currentview I can see the cardnumber column with data.

I looked in BO mapper and there doesn't look to be anyplace there to fake the BO into created a property (probably just as well as I assume it could not be updateable)  Thought a custom field prop would be the way to go but

Return Cardnumber gets the error that it must be declared - but I'm not sure what the syntax is to tell it the field will be in the cursor at runtime

( I do realize that if I add a custom prop in this way I will probably need to always be sure it is provided in each data access scenario.  Does that mean I should be creating a view on the back end so the field is present in the definition when the bizobj is mapped?  No problem, if that's the case but wanted to make sure there wasn't another trick I was missing as I might want to display something like this without having to create an updateable view on the back end)

TIA

Charles

Hi Charles,

Your custom field property should return a value and in your code the cardnumber has not value.  Modify the Return value to return the calculated field as follow:

Edhy Rijo

Sorry, it should be:

Edhy Rijo

Thanks, Edhy

I did get my two custom props (the cust_lastname in the tutorial and my new prop) into an array properly.  ( I rewrote my proc to pull the most recent order as creditcard is a varchar(max) and may be encrypted and I just wanted to simplify)

My new prop is Orderpo but my problem is in the GET SET

<Browsable(False), _
BusinessFieldDisplayInEditor(), _
Description("The customer's last order."), _
DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)> _
Public ReadOnly Property [orderpo]() As System.String
Get

Return orderpo

End Get
End Property

I get a warning that variable orderpo is used before it has been assigned a value and that may result in a null ref exception at runtime

If i use me.orderpo (which is available through intellisense) I get an error 'Expression recursivelyh calls the containing property'

Obviously I'm missing something. 

I think I've got is

RETURN me.currentrow.item("orderpo")

seems to give me exactly what I want (I was trying something like that in the watch window earlier with me.currentview.item("orderpo") but of course now I see why that wouldn't work)

Found the right syntax by just searching around here on all the message re custom properties

This framework, this forum and this community ROCKS !!

Charles,

It looks like you got it going.  I didn't work this weekend so I wasn't out on the forum much.  But you did get it figured out.  Returning a field or column from a joined table is a must in the disconnected world.  So in order to interact with it, just create the custom property and then...as you discovered...call the Me.CurrentRow.Item("MyField") property on the return an you have it.  If you intend to bind this field to anything, you will need to override the GetCustomBindablePropertyDescriptors method and return a ReflectionPropertyDescriptor.  There are a ton of posts and docs regarding this, but if you get stuck just let me know.

I agree Thanks for your kind words...and thanks for your input, Edhy!  I know that Charles appreciated it!

Trent, thanks for the explanation.

Charles, I am glad you find it.  In fact I was not sure on the right answer since I have not done that yet, but I knew it has something to do with the return value of the custom field property, now I know

Edhy Rijo

Thanks to a some posts between Greg and Peter Jones I figured out the array and the sample in the tutorial make more sense

Once the project is rebuilt the field appears in the enumeration for binding field and displays just what I need.  Of course the field is read only, as it should be.

Charles,



Glad you got it going! Here are some other things to consider when using custom properties that will reference a "special" field in the data table:



- You probably should check for a current row...if there is no current row, the .Item("orderpo") will throw an exception



- You also probably need to handle the case were the column isn't in the table. I.e. what if you have a fill that doesn't include the "orderpo" column, you forget and reference it anyway...boom. You would just use a Try/Catch and throw an exception that will quickly let you know what you forgot.



Just a couple of things that I spent too much time on in the beginning, thought I'd share

Or just test on the count: