DropDownGrid set default from parent DataGrid

i have a form i am creating that needs to edit rows of a table, one of the columns is an Id that will be edited with a dropdown. this Dropdown needs to use data from a table and show the user multiple columns.

i have the form and the DataGrid and the DropdownGrid each working to where i can put the data grid to edit mode and the dropdown Grid has the possible options to pick from.

so far so good.....

but when i got to edit mode the dropdown needs to take the current id and set that as the selected item/ default item.
i am trying to get the right way to make that work but so far i cant seem to get it...

i am trying to use the @bind-Value= but i seem to be missing somehting about how to set that up...

If the item is not part of the current DropDownDataGrid page of data it will not be selected, you can manually retrieve and set however SelectedItem property.

in my first case the item is in the first page , my datagrid displays the name of the selected item.
when i click on the grid row edit button i get the dropdowngrid to be shown but no selected item is set.
when i open the drop down i have 2 rows and none of them are selected but if i click on one it is then set.

can we get a sample of how to do the right binding ? is visual studio i have been trying to get an expression in the @bind-Value= but it keeps giving me an error about the expression cant be converted to the right type

is @bind-Value the right thing to use ?
it seems like it wants an instance of the collection not a key value ....
i was trying to give it the int key value that is the selected item....


Our samples source code is here:

I have seen the standard samples and they do not help me in this case.

also the page : GitHub shows the dropdowngrid but none of the samples shows a default selected value.

also i am trying to do the same kind of effect with a simple radzen dropdown and get the same result.
the item that shows up in the grid is not the selected item in the dropdown.
i need to know how to make this work....

still struggling with this ..... not sure what is going on...
i must not be setting the value right but cant seem to find the right way to set it.

i have a collection of a Type that is what the drop down grid will show and one property in the type is an int id that is used in the sql database relationship.

i have a type that is returned by a web service that is a parent record that has one or more child records that are "payment Details"
each payment detail has the id that relates the payment detail claim property to the list of claim types.

i am not sure if i need to set the @bind-Value to the int id or to an object of the same type as the dropdown grid will display ?
i get errors with some expressions i am trying.
they all seem to revolve around the data type and the delegate that razor is trying to hook up.

at compile time one version gives me:
CS1503 Argument 2: cannot convert from 'Microsoft.AspNetCore.Components.EventCallback' to 'Microsoft.AspNetCore.Components.EventCallback'

or at run time i get:

Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer: Warning: Unhandled exception rendering component: Operator '==' incompatible with operand types 'Int32' and 'BenefitOffering'

Operator '==' incompatible with operand types 'Int32' and 'BenefitOffering' (at index 10)
Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost: Error: Unhandled exception in circuit ...