Server-Side Scripting/Strings and Files/Go
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routes/lesson5.go
[edit | edit source]// This program reads a user-selected text file of Celsius
// temperatures and converts the temperatures to Fahrenheit.
//
// File format:
// Country,MaximumTemperature
// Bulgaria,45.2 °C
// Canada,45 °C
//
// References:
// https://www.mathsisfun.com/temperature-conversion.html
// https://golang.org/doc/
// https://tutorialedge.net/golang/go-file-upload-tutorial/
package routes
import (
"html/template"
"io/ioutil"
"net/http"
"mime/multipart"
"path/filepath"
"strconv"
"strings"
)
func Lesson5(response http.ResponseWriter, request *http.Request) {
response.Header().Set("Content-Type", "text/html; charset=utf-8")
type Data struct {
Table template.HTML
}
result := ""
switch request.Method {
case "GET":
result = ""
case "POST":
result = "<h1>Temperature Conversion</h1>";
file, handler, err := request.FormFile("file")
if err != nil {
result += err.Error()
}
result += "<h2>" + handler.Filename + "</h2>"
result += processFile(file);
default:
result = "Unexpected request method: " + request.Method
}
data := Data{template.HTML(result)}
path := filepath.Join("templates", "lesson5.html")
parsed, _ := template.ParseFiles(path)
parsed.Execute(response, data)
}
func processFile(file multipart.File) string {
result := "<table><tr><th>Fahrenheit</th><th>Celsius</th></tr>"
bytes, err := ioutil.ReadAll(file)
if (err != nil) {
return err.Error()
}
text := string(bytes)
text = strings.TrimSpace(text)
lines := strings.Split(text, "\n")
for _, line := range lines {
result += processLine(line)
}
result += "</table>"
return result
}
func processLine(line string) string {
// skip heading
index := strings.Index(line, "Country,MaximumTemperature")
if index >= 0 {
return ""
}
start := strings.Index(line, ",")
end := strings.Index(line, " °C")
if start < 0 || end < 0 {
return "Invalid file format: " + line + "<br>"
}
celsius, err := strconv.ParseFloat(line[start + 1:end], 64)
if err != nil {
return err.Error()
}
fahrenheit := celsius * 9 / 5 + 32
result := "<tr><td>" + strconv.FormatFloat(celsius, 'f', 1, 64) + "</td>"
result += "<td>" + strconv.FormatFloat(fahrenheit, 'f', 1, 64) + "</td></tr>"
return result
}
templates/lesson5.html
[edit | edit source]<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Lesson 5</title>
<link rel="stylesheet" href="styles.css">
<style>
p {
min-height: 1em;
}
</style>
</head>
<body>
<h1>Temperature Conversion</h1>
<p>Select a file of Fahrenheit temperatures for conversion:</p>
<form method="POST" enctype="multipart/form-data">
<input type="hidden" name="MAX_FILE_SIZE" value="1048576" />
<input type="file" id="file" name="file">
<input type="submit">
</form>
{{.Table}}
</body>
</html>
Try It
[edit | edit source]See Server-Side Scripting/Routes and Templates/Go to create a test environment.