[Solved] ASP.NET Core 10 Razor Pages: how to use ObjectDatasource where data source is a method returning a ValueTuple

[Nitin]

I have a class representing a SQL Server stored procedure output. The SP returns two datasets. I have a C# method that takes in parameters and runs the SP. It returns a ValueTuple (2 Lists - 1 each for the SP returned dataset). I tried to assign this method as the data source to an ObjectDatasource in the report (using standalone Report Designer); however I get an unexpected error (screenshot attached). Probably, it doesn't support a ValueTuple since if I connect to the class itself then it connects. If this is the case, what is the workaround?

[Petar]

Hi Nitin,

Thank you for sharing the screenshot of the observed behavior.

I can confirm that `ValueTuple` is not among the supported types for the ObjectDataSource component; please check Supported object types | ObjectDataSource Component Overview for more information.

As a potential workaround, you may consider creating a wrapper method that returns data in a supported type (for example, `List`). Keep in mind that the ObjectDataSource component supports only a single result set, so you may need to combine the values from the tuple into a single collection.

I also noticed that the data source member expects a `DataService` object as its first parameter, which can be problematic to pass through the designer UI, as it is designed to work with expression-based values. To avoid potential issues, I would recommend simplifying the wrapper method’s parameters (for example, by accepting a string or another easily configurable type instead).

If you continue to experience issues after making this change, I would strongly recommend enabling a trace listener in the Standalone Report Designer, as the generated log file can provide valuable insight into the root cause of the problem (see Troubleshooting Standalone Report Designer).

Regards,
Petar
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