This is another take on accessing dynamic objects in F# There I'm using let y = x.Where(fun x -> x.City ="London").Select("new(City,Zip)")
to parametrize the query and extract the necessary items. These would correspond to columns in an SQL query, and be represented by a property of the datacontext. This is the part that I would like to pass in as a parameter.
type Northwind = ODataService<"http://services.odata.org/Northwind/Northwind.svc">
let db = Northwind.GetDataContext()
let query2 = query { for customer in db.Customers do
select customer} |> Seq.toArray
let qryfun (x:Northwind.ServiceTypes.Customer) =
query { for x in query2 do
select (x.City,x.CompanyName,x.Country)}
Basically I would like to pass in not only x
but also x.*
. As I'm accessing one database that is fixed, I can factor out x. However I now have 40 small functions extracting the different columns. Is it possible to factor it out to one function and pass the property as an argument? So sometimes I extractx.City
but other times x.Country
. I have tried using quotations however cannot splice it properly and maybe that is not the right approach.
Regarding quotation splicing, this works for me:
open System.Linq
type record = { x:int; y:string }
let mkQuery q =
query {
for x in [{x=1;y="test"}].AsQueryable() do
select ((%q) x)
}
mkQuery <@ fun r -> r.x, r.y @>
|> Seq.iter (printfn "%A")
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