Typed DataSet Exception...

[Kieron]

Hi,

I keep getting the following error:

************** Start **************
System.Reflection.TargetInvocationException: Property accessor CompanyName
on object
CRMDataSet+Customer
sRow threw the following exception:Cannot get value because it is
DBNull. ---> System.Data.StrongTypingException: Cannot get value because it
is DBNull. ---> System.InvalidCastException: Cast from type DBNull to type
String is not valid.
at Microsoft.VisualBasic.CompilerServices.StringType.FromObject(Object
Value)
at
CustomersRow.get_CompanyName() in CRMDataSet.vb:line 1002
at
CustomersRow.get_CompanyName() in CRMDataSet.vb:line 1004
************** End **************

The column in question is allowed to have NULL values, and the records its crashing on has NULL values in the CompanyName column.
Ive tried re-generating the Customers section of the schema but nothing seems to work. The columns .AllowDBNull is True, so that shouldnt be an issue.

Can someone please explain whats going on!!

 

[Heiko]

Horrible!

When the XML descriptions of the datatables are generated, these descriptions do NOT contain one specific attribute, which will allow for "isDBNull" Properties to be created.

<xs:element name="PRS_GUID" codegen:nullValue="_empty" type="xs:string" />

The "codegen:nullValue" part has to be added manually - or program a helper that will do it for you (At least I havent found a better way yet).

What we have done: Written a helper program which will add that attribute to the XML files.

 

[Nerseus]

Im not sure about the codegen:nullValue thing. I use the minOccurs property - set it to 0 to allow DBNull values. I would have thought this got put in if you created the table by dragging from server explorer, but havent it in awhile.

-Nerseus