F# / SIlverlight Binding to algebraic datatypes...

Question

Given a data structure of:

type Candidate =  SalesRep of SalesRep | Analyst of Analyst

type ScorableCandidate = {
    candidate: Candidate ;
    mutable comments: string ;
    mutable score: int ;
}

and a data grid that wants to be able to display either of the candidates, is it possible to bind (using the WPF binding) to the ScorableCandidate?

<telerik:GridViewDataColumn Header="First Name" DataMemberBinding="{Binding candidate.fname}" IsFilterable="False" Width="100"/>

I am thinking not, as the binding syntax would bneed to be able to deconstruct the type - which I don't think is possible.

Thx

T

Answer 1

I believe that you shouldn't have any trouble accessing the candidate field of the record type (because record fields appear as standard .NET properties).

Regarding the discriminated union - I like the suggestion to use custom type convertors as Juliet suggests. Another simpler option would be to expose the fname field (which is shared by both SalesRep and Analyst if I understand your example correctly) as a property of the Candidate type:

type Candidate = 
  | SalesRep of SalesRep 
  | Analyst of Analyst 
  member x.Name = 
    match x with
    | SalesRep s -> s.fname
    | Analyst a -> a.fname

Then you should be able to use standard WPF binding syntax for binding to properties.