F# insert row into Excel dynamically

Question

I need to insert rows in excel dynamically. I am generating an invoice which can have a varied number of transactions and their for require a row for each transaction.

I want to start with one row (row 17) and duplicate it for n number of transactions.

Can anyone shed any light on doing this in F#?

Answer 1

I wouldn't necessarily recommend this approach, but if you're ok with dynamically being interpreted as by means of F#'s dynamic operator ( an implementation of which can be found here ), then you can do Interop without any reference to a specific library.

let xlApp = System.Runtime.InteropServices.Marshal.GetActiveObject "Excel.Application"
let rng : obj = xlApp?ActiveWorkbook?ActiveSheet?Rows(17)
rng?Copy()
rng?Insert()

That is, copy a row to the clipboard, and insert it at the same position.

Edit

It turns out that many Reflection-based definitions of the dynamic operator aren't suited to interop, including the one linked above. Supplying my own:

let (?) (o: obj) name : 'R =
    let bindingFlags = System.Reflection.BindingFlags.GetProperty
    let invocation args =
        o.GetType().InvokeMember(name, bindingFlags, null, o, args)
    let implementation args =
        let argType, resType = FSharpType.GetFunctionElements typeof<'R>
        if argType = typeof<unit> then [| |]
        elif FSharpType.IsTuple argType then FSharpValue.GetTupleFields args 
        else [| args |]
        |> invocation
        |> fun res -> if resType = typeof<unit> then null else res

    if FSharpType.IsFunction typeof<'R> then
        FSharpValue.MakeFunction(typeof<'R>, implementation)
    else invocation null
    |> unbox<'R>

We can now define a function in order to insert a variable number of copied rows.

let copyAndInsertRow17 n =
    if n > 0 then
        let xlApp =
            System.Runtime.InteropServices.Marshal.GetActiveObject "Excel.Application"
        let sheet = xlApp?ActiveWorkbook?ActiveSheet
        sheet?Rows(17)?Copy()
        sheet?Range(sheet?Rows(17 + 1), sheet?Rows(17 + n))?Insert()