Error loading guid NULL-value (MS SQL)

Radzen Studio Blazor Server
1

Hi!
Asking you help with next error, while loading record from MS SQL:

Blockquote
dotnet: fail: Microsoft.EntityFrameworkCore.Query[10100]
An exception occurred while iterating over the results of a query for context type 'Lic.Data.AppLicContext'.
System.Data.SqlTypes.SqlNullValueException: Data is Null. This method or property cannot be called on Null values.
at Microsoft.Data.SqlClient.SqlBuffer.ThrowIfNull()
at Microsoft.Data.SqlClient.SqlBuffer.get_Guid()
at Microsoft.Data.SqlClient.SqlDataReader.GetGuid(Int32 i)
at lambda_method(Closure , QueryContext , DbDataReader , ResultContext , Int32 , ResultCoordinator )
at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
Blockquote

My guess is: Radzen doesn't expect NULL value in column with GUID (uniqueidentifier) type.
Is that right?

I've found a recommendation from MS to add NULL-check for function like GetGuid, m. b. this would be a solution for future releases?

In Remarks section:
Call IsDBNull to check for null values before calling this method.

Thank you!

2

Most probably nullable field is wrongly mapped to non nullable property. Can you check the property definition and the database definition?

3

All properties are generated by Radzen while creating "DataGrid with Form" page, no manual changes.

DB table fields (AD_guid is nullable)

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Data in table

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Properties of auto-generated form field for AD_guid

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image1326×193 17 KB

As far as i understand, this question mark (?) means field can be NULL

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4

If this helps:
Error strikes when trying to open a page (page just not opens)
i.e. first record is loading into the form

Here is page Load event code, just in case (also auto-generated, no manual changes)

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5

Will you post the property definition in c# model?

6

Is that file correct?
[path_to_project]\server\Models\AppLic\ListAccount.cs

Sorry, not too familiar with programming. If file is wrong - give a clue please :slight_smile:

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7

Everything looks correct, I’m not sure why you get this exception.

8

App working great after changing GUID to a value
With NULL in GUID - exception is back

Sadly, in this table GUIDs can be unknown, and then are set to NULL

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9

Sorry for asking - is exception reproduced by you?
Looks like there is need for additional check for NULL on retrieving values from GUID-type columns...