Server code to save uploaded files

Question

This code basically saves an uploaded file to the server. I am wondering if there is anything that I can do to tighten this code up. I am very new to F# so I'm still having trouble breaking away from the C# way of doing things.

/// Create file paths
/// Returns a tuple (server path * link path * file number)
let createPath (file : HttpPostedFileBase) =

    // server directory path
    let serverDirPath = 
        HttpContext.Current.Server.MapPath(@"~/Uploads")

    // get the file name
    let origFileName = file.FileName

    // get the extension
    let extension = Path.GetExtension(origFileName)

    // get the file size in bytes
    let fileSize = file.ContentLength

    // directory check
    let pathExists() = Directory.Exists(serverDirPath)

    // create directory
    let createDir() = 
        if not (pathExists()) then
            Directory.CreateDirectory(serverDirPath) |> ignore
    createDir()

    // find current file name
    let findCurrentFileName() = 

        // check if row exist
        let rowCount = 
            query{
                for row in db.Uploads do
                select row
                count
            }

        // get file number
        let fileNumber = 
            if rowCount < 1
                then
                    1
                else
                    query{
                        for row in db.Uploads do
                        select (row.FileNumber + 1)
                        head
                    }

        // final path
        let finalServPath = 
            serverDirPath + @"\" + fileNumber.ToString() + extension

        // download link
        let linkPath = 
            finalServPath.Replace(serverDirPath + @"\", @"~/Uploads/") 

        finalServPath, linkPath, fileNumber

    findCurrentFileName()

/// Save file to server and path to db.
let SaveUpload (file: HttpPostedFileBase) (title : string) = 


    // create the path including filename
    let servPath, linkPath, fileNumber = createPath file 

    // save file to server
    file.SaveAs(servPath)

    // create new row for db table
    let newUpload = 
        new dbSchema.ServiceTypes.Uploads(Title = title,
                                            FilePath = servPath,
                                            Size = file.ContentLength.ToString(),
                                            FileNumber = fileNumber,
                                            LinkPath = linkPath)
    // insert new row
    insertRowIn db.Uploads newUpload

    // save to db
    saveToDb()

Answer 1

I think that you're using comments unnecessarily. If you set a variable called fileNumber, the comment // get file number doesn't tell the reader anything new and only clutters the code.

---

// directory check
let pathExists() = Directory.Exists(serverDirPath)

// create directory
let createDir() = 
    if not (pathExists()) then
        Directory.CreateDirectory(serverDirPath) |> ignore
createDir()

I don't see any reason to have createDir or pathExists as separate functions, since they're short and not reusable.

And as Daniel mentioned in a comment, the check is not actually necessary. So, I would simplify this code to just:

Directory.CreateDirectory(serverDirPath) |> ignore

---

// check if row exist
let rowCount = 
    query{
        for row in db.Uploads do
        select row
        count
    }

// get file number
let fileNumber = 
    if rowCount < 1
        then
            1
        else
            query{
                for row in db.Uploads do
                select (row.FileNumber + 1)
                head
            }

You can use headOrDefault here, to get rid of the first query:

// get file number
let fileNumber = 
    query {
        for row in db.Uploads do
        select row.FileNumber
        headOrDefault
    } + 1

Also, you're not using any ordering in the query, are you sure the largest FileNumber is always going to be the first one?

---

let finalServPath = 
    serverDirPath + @"\" + fileNumber.ToString() + extension

You can use Path.Combine() to concatenate parts of a path:

let finalServPath = 
    Path.Combine(serverDirPath, fileNumber.ToString() + extension)