How to read input from a HTML form and save it in a file - Golang

Question

I am trying to set up a very simple web server where the user access a site and writes a string and an int.Then I want to save these two inputs, my idea was to do it to a text file that also can be displayed in the browser: .../textfile/

I don´t know what the norm on SO is on how much code is OK to post but here is what I have so far:

type Person struct {
    name  string
    hours int
}

const filename string = "timelister"

func upload(w http.ResponseWriter, r *http.Request) {
    t, _ := template.ParseFiles("upload.html")
    t.Execute(w, nil)
}

func (person *Person) open() {
    newFilename := filename + ".txt"
    _, err := os.OpenFile(newFilename, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0666)
    if err != nil {
        log.Fatal("Open Filename: ", err)
    }
}

func returnInput() //want to implement this
func saveInput() //want to implemet this


func main() {
    http.HandleFunc("/", upload)
    http.ListenAndServe(":8080", nil)

}

And my HTML-form: (without all the formating)

     Name: <input type="text" name="Name">
        <input type="submit" value="submit"></br>
     Hours: <input type="text" name="Hours">
            <input type="submit" value="submit">

So my initial thoughts was to implement two functions returnInput() and saveInput() but maybe there are som built in functions that are easier to use?

If somebody could point me in the right direction on how to save the input from the HTML form than I would be very greatful! Thanks in advance.

dskinner · Accepted Answer · 2012-09-20 14:10:05Z

14

You'll need to pick a format to write to the file. Let's pick JSON for no reason in particular. So given a form like:

<form action="/save" method="post"> ... </form>

you could have the following handler

import (
    "strconv"
    "http"
    "os"
    "encoding/json"
)

type Data struct {
    Name string
    Hours int
}

func save(w http.ResponseWriter, r *http.Request) {
    name := r.FormValue("Name")
    hours, err := strconv.Atoi(r.FormValue("Hours"))
    if err != nil {
        http.Error(w, err.Error(), 500)
        return
    }

    data := &Data{name, hours}

    b, err := json.Marshal(data)
    if err != nil {
        http.Error(w, err.Error(), 500)
        return
    }

    f, err := os.Open("somefile.json")
    if err != nil {
        http.Error(w, err.Error(), 500)
        return
    }

    f.Write(b)
    f.Close()
}

func init() {
    http.HandleFunc("/save", save)
}

answered Sep 20, 2012 at 14:10

dskinner

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2 Comments

miner Over a year ago

Thank, it was really helpful. I had been trying with the FormValue but since I am very new to programming I missed the bit about encoding. But you made it very clear to me.

dskinner Over a year ago

Sure, checkout the pkg docs on encoding, golang.org/pkg/encoding You could for example read/write the raw struct with encoding/binary pkg if that's what you want. JSON is just a nice middle ground for explaining something and inspecting the result easily.

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