Create and User User Define Function in edmx - entity-framework

Question

i want to create one function in edmx which return scaler value,
how to create it in SSDL and how to access it in code?

Answer 1

One problem you have is your SSDL is automatically generated by the 'EntityModelGenerator', so editing it will be wiped out by a rebuild. Your edits need to be done in th EDMX file.
So firstly, you have to decide is (1) your return value a calculation of sorts (i.e. adding values together in the application, rather than at database level), or (2) is it a direct call to a database stored procedure?
(1) First step is to add the function XML definition into your EDMX file:
<Function Name="LineTotal" ReturnType="decimal">
<Parameter Name="lineTotal" Type="MyDbModel.OrderDetail">
<DefiningExpression>
od.Price * od.Quantity
</DefiningExpression>
</Parameter>
</Function>
Now, although your EDMX knows about this function, your IntelliSense won't. So you have to add some code to make this work. It is a best practice to place these functions in a seperate class.
public class ModelDefinedFunctions
{
[EdmFunction("MyDbModel" , "LineTotal")] //Model Name and Function Name
public static decimal LineTotal(OrderDetail od)
{
throw new NotSupportedException("LineTotal cannot be directly used.");
}
}
Entity Framework will know to redirect this function call to the EDMX instead. Any direct call to this method, where the model does not exist will throw an exception.
You can then call it in your LINQ queries like
var productValues = from line in model.OrderDetails
select new
{
od.ProductID,
od.Price,
od.Quantity,
LineTotal = ModeDefinedFunctions.LineTotal(line)
};
(2) If you are adding a stored procedure directly, it is easier to drag and drop it onto the EDMX designer. There is a [FunctionImport()] attribute, but I haven't used it. You can drag and drop and see what code it generates in the EDMX file?
Alternatively, you can call the model.ExecuteCommand(<spname> , params object[] values
) stored procedure execution method.