f#将seq转换为seq记录。

Question

我试图从数据库中读取数据，并将它们转换为seq记录。执行时

open FSharp.Data
open FSharp.Data.SqlClient


type foo = {name:int; author:int}

[<Literal>]
let query = "Select * from Authors"

[<Literal>]//DESKTOP-5RIV0K1
let connectionString = "Data Source=DESKTOP-5RIV0K1;Initial Catalog=TestBase;Integrated Security=True"

let cmd = new SqlCommandProvider<query,connectionString>(connectionString)

let result = cmd.Execute() |> printfn "%A"

result

我得到了

seq
  [{ AuthorID = 1; Name = Some "2" }; { AuthorID = 2; Name = Some "3" };
   { AuthorID = 3; Name = Some "4" }] 

但是，当我试图用下面的代码将seq转换为seq时

let result = 
    for item in cmd.Execute() do
    match item.Name, item.AuthorID with
        | Some itemName, Some itemAuthor ->
            {name = itemName; author = Some itemAuthor }
        | _ -> ()

我搞错了

一些itemAuthor 错误FS0001这个表达式应该有'int‘类型，但是这里有’a选项‘类型

我做错什么了？

Answer 1

你想要匹配这样的记录.

{ AuthorID = 1; Name = Some "2" }

...using的图案看起来像这样..。

| Some itemName, Some itemAuthor ->

注意，您的AuthorID是一个整数。它不是Option<int>。因此，带有两个值的模式是不兼容的。你应该有这样的模式.

| Some itemName, itemAuthor ->