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 it's crashing on has NULL values in the CompanyName column.

I've tried re-generating the Customers section of the schema but nothing seems to work. The column's .AllowDBNull is True, so that shouldn't be an issue.

 

Can someone please explain what's 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 haven't found a better way yet).

 

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

[Nerseus]

I'm 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 haven't it in awhile.

 

-Nerseus