Using Postgres with F#

Question

I'm trying to connect F# with an existing Postgresql database in a way that lets me take advantage of the database types during development (via Type Providers or Entity Framework, or a combination thereof).

The raw connection is straightforward to do using Npgsql. For example, the following code segment prints the contents of a Postgres table using F#.

open Npgsql

let connectionString = "(my postgres connection string)"

let getResultSet (connection:NpgsqlConnection) (queryString:string) =
    let command = new NpgsqlCommand(queryString, connection)
    let dataReader = command.ExecuteReader()
    seq {
        while dataReader.Read() do
            yield [for i in [0..dataReader.FieldCount-1] -> dataReader.[i]]
    }

let printResults = 
    let conn = new NpgsqlConnection(connectionString)
    conn.Open()
    try
        let resultSet = getResultSet conn "select * from myTable;"
        for r in resultSet do
            for d in r do
                printf "%s\t" (d.ToString())
            printfn ""
    finally
        conn.Close()

What's the best way to get a Type Provider for this set up or enable using Entity Framework with Postgresql on F#?

Answer 1

Since Npgsql is a ADO.NET provider you should be able to use the SqlEntityConnection type provider with an entity framework DBML file.

For more information see: http://msdn.microsoft.com/en-us/library/hh362322.aspx.