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module SQL
open System
open System.Data
open System.Data.SqlClient
open System.Text.RegularExpressions
open Microsoft.FSharp.Reflection
open Xunit
let connectionString = "data source=.;user id=sa;password=a;initial catalog=SomeDatabase"
// primitive implementation, doesn't work
let runQuery1 (query: PrintfFormat<'a, _, _, IDataReader>) : 'a =
let proc (a: int) (b: string) : IDataReader =
printfn "%d %s" a b
null
unbox proc
let PrintfFormatProc (worker: string * obj list -> 'd) (query: PrintfFormat<'a, _, _, 'd>) : 'a =
if not (FSharpType.IsFunction typeof<'a>) then
unbox (worker (query.Value, []))
else
let rec getFlattenedFunctionElements (functionType: Type) =
let domain, range = FSharpType.GetFunctionElements functionType
if not (FSharpType.IsFunction range)
then domain::[range]
else domain::getFlattenedFunctionElements(range)
let types = getFlattenedFunctionElements typeof<'a>
let rec proc (types: Type list) (values: obj list) (a: obj) : obj =
let values = a::values
match types with
| [x;_] ->
let result = worker (query.Value, List.rev values)
box result
| x::y::z::xs ->
let cont = proc (y::z::xs) values
let ft = FSharpType.MakeFunctionType(y,z)
let cont = FSharpValue.MakeFunction(ft, cont)
box cont
| _ -> failwith "shouldn't happen"
let handler = proc types []
unbox (FSharpValue.MakeFunction(typeof<'a>, handler))
let sqlProcessor (sql: string, values: obj list) : IDataReader =
let stripFormatting s =
let i = ref -1
let eval (rxMatch: Match) =
incr i
sprintf "@p%d" !i
Regex.Replace(s, "%.", eval)
let sql = stripFormatting sql
let conn = new SqlConnection(connectionString)
conn.Open()
let cmd = conn.CreateCommand()
cmd.CommandText <- sql
let createParam i (p: obj) =
let param = cmd.CreateParameter()
param.ParameterName <- sprintf "@p%d" i
param.Value <- p
cmd.Parameters.Add param |> ignore
values |> Seq.iteri createParam
upcast cmd.ExecuteReader(CommandBehavior.CloseConnection)
let runQuery a = PrintfFormatProc sqlProcessor a
[<Fact>]
let runQueryTest() =
use results = runQuery "select top 5 * from usuario where nroid = %d and nombres = %s" 13598 "pepe"
while results.Read() do
printfn "%A" results.["nroid"]
use results = runQuery "select top 5 * from usuario"
while results.Read() do
printfn "%A" results.["nroid"]
()
Owner

mausch commented Jul 5, 2011

This is now part of the FsSql project

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