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New method on form datasource by extension not working

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Posted on by BrandonSA

1,673

Hi everyone

I've implemented a new method on a form datasource by extension (on the SalesLine datasource of the SalesTable form to be exact).

When I call the method however, I get this error message:

"Error executing code: FormDataSource object does not have method "xxx""

I couldn't find much documentation on how to do it, but eventually found these:

https://community.dynamics.com/365/financeandoperations/f/dynamics-365-for-finance-and-operations-forum/305905/calling-a-form-datasource-method-in-d365

https://community.dynamics.com/365/financeandoperations/f/dynamics-365-for-finance-and-operations-forum/291411/how-to-use-otb-custom-form-datasource-methods-in-extension-class-in-d365fo

I understand the principle of casting a FormDataSource object to a more generic/super object. Yet when I implement it, I get an error. Here is my implementation:

[ExtensionOf(formDataSourceStr(SalesTable, SalesLine))]

final class SalesTableDSSalesLine_Extension

{

public void blah(boolean _variable)

{

// do something

}

}

and the call:

[FormDataFieldEventHandler(formDataFieldStr(SalesTable, SalesLine, ItemId), FormDataFieldEventType::Modified)]

public static void ItemId_OnModified(FormDataObject sender, FormDataFieldEventArgs e)

{

Object dsObject = sender.datasource();

dsObject.blah(true);

}

The only difference I can see is that other implementations are calling this from a form control, and not a form data field control, but surely that makes no difference.

The error message seems to indicate that the cast isn't happening properly: It's calling the method off an 'Object' object, but it still says that the method doesn't exist for 'FormDataSource' objects - strange.

What am I doing wrong?

Any help appreciated.

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Suggested answer

Waed Ayyad 8,874 Super User 2025 Season 2 on at

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New method on form datasource by extension not working

Hi,

Try to use the following code in order to get your DataSource:
FormRun formRun = sender.formRun(); FormDataSource salesLine_ds = formRun.dataSource(formDataSourceStr(SalesTable,SalesLine)); salesLine_ds .blah(true);

Thanks,

Waed Ayyad

If this helped, please mark it as "Verified" for others facing the same issue

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Sourav Mazumdar 38 on at

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New method on form datasource by extension not working

Hi BrandonSA,

Please try the below approach inside form control event handler.

FormRun formRun = sender.formRun();

Object Table_ds = formRun.dataSource(formDataSourceStr(Formname,Datasourcename));

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AtulMP 4 on at

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New method on form datasource by extension not working

Hello,

There are some suggestions you can try to solve your problem.

1. Create an Extension Class: Define your method in an extension class for the data source.

[ExtensionOf(formDataSourceStr(SalesTable, SalesLine))]
final class SalesTableDSSalesLine_Extension
{
public void blah(boolean _variable)
{
next blah(_variable); // Call the base method if needed
// Your custom logic here
}
}

2. Use Chain of Command (CoC): Extend the method using CoC to ensure it integrates with the base method.

[ExtensionOf(formDataSourceStr(SalesTable, SalesLine))]
final class SalesTableDSSalesLine_Extension
{
public void blah(boolean _variable)
{
next blah(_variable); // Call the base method if needed
// Your custom logic here
}
}

3. Call the Extended Method: Cast the data source correctly and call the extended method.
[FormDataFieldEventHandler(formDataFieldStr(SalesTable, SalesLine, ItemId), FormDataFieldEventType::Modified)]
public static void ItemId_OnModified(FormDataObject sender, FormDataFieldEventArgs e)
{
SalesLine ds = sender.data source() as SalesLine;
if (ds)
{
SalesTableDSSalesLine_Extension extendedDs = ds as SalesTableDSSalesLine_Extension;
if (extendedDs)
{
extendedDs.blah(true);
}
}
}

This approach ensures your custom method is recognised and executed correctly.

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RAGU Veelead 6 on at

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New method on form datasource by extension not working

Hi BrandonSA,

try to change the code in the form data source field - chain of command.

[ExtensionOf(formDataFieldStr(SalesTable,SalesLine,ExternalItemId))]
final class AMM_SalesLineExtItemId_Extension
{

void modified()
{
SalesLine salesLine;
FormDataObject formdo = any2Object(this) as FormDataObject;
salesLine = formdo.datasource().cursor();
next modified();
info(salesLine.salesid);
}
}

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WillWU 22,359 on at

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RE: New method on form datasource by extension not working

Hi Brandon,

Sorry the problem cannot be reproduced in my environment.

As above said, if the method has to be reused, you could put it to another place.

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Martin Dráb 235,961 Most Valuable Professional on at

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RE: New method on form datasource by extension not working

Duplicating code would indeed be wrong, but what prevents you to put the code to a separate method that you'll call where needed? It's what you're doing with blah(), you're just trying to place to a place where it's difficult to call. Would a class method does the same job while being easy to call?

Maybe the hack with Object doesn't work with methods defined in extensions. If you wish, you can test it - create a custom form, define a data source method and call it from a handler. Then remove the method, define it through an extension and run the solution again.

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Sergei Minozhenko 23,093 on at

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RE: New method on form datasource by extension not working

Hi BrandonSA,

In examples you have provided, standard methods are used, but you are adding new method via CoC. It could be that this feature could be broken or never was implemented.

Have you considered to move your code from data source lelve to table level for reusability (if possible) or at least to form level?

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BrandonSA 1,673 on at

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RE: New method on form datasource by extension not working

Thanks Will. I could put all the blah functionality in the event handler, but then I wouldn't have a resuable method on the datasource. I would have to copy the code of blah to every place that needed to use it.

Besides, I don't understand why my code isn't working. I've implemented it in the same way as the examples I gave, and those people say their code works, so just wondering why mine isn't.

Thanks

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BrandonSA 1,673 on at

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RE: New method on form datasource by extension not working

Thanks Blue, but it is being implemented on DataSource level

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WillWU 22,359 on at

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RE: New method on form datasource by extension not working

Hi Brandon,

Try to change the code in your form data source field event handler.

FormRun formRun = sender.datasource().formRun(); Object salesLine_ds=formRun.dataSource(formDataSourceStr(SalesTable,SalesLine)); salesLine_ds.blah(true);

Actually you could write your 'blah' method in the event handler, why you have to create the new one in datasource?

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