Go Template

This template allows you to code functions using Golang 1.15. The skeleton of this template looks like this:

package function

import (
        "io/ioutil"
        "net/http"
)
func Handle(w http.ResponseWriter, r *http.Request) {
        var body []byte

        if r.body !=nil {
                    defer r.Body.Close()
                    body, _= ioutil.ReadAll(r.Body)
        }

        w.WriteHeader(http.StatusOK)
        w.Write(body)

Handlers are part of the Go language, so there is really nothing new in this template. Just make sure you write in the http.ResponseWriter in the correct order! You can easily find tons of great information on how to use them. Here are few sources:

• Official Go documentation
• Go by Example: HTTP Servers

Adding third-party dependencies is not allowed at the moment, although this will change in the future. For now, you can use the following pre-installed dependencies (this list will grow):

• resty: A really nice to use and simple HTTP and REST client library for Go.

Anything you write to stderr will be saved as a log entry. You can use the log package for that:

package function

import (
        "log"
        "net/http"
)

func Handle(w http.ResponseWriter, r *http.Request) {
        // ...

        log.Println("My log entry!")
        
        // ...

}

Adder

This is a really simple function that gets a comma-separated list of numbers in the request body and return the sum of them (or an error if the input format is invalid).

package function

import (
        "fmt"
        "io/ioutil"
        "net/http"
        "strconv"
        "strings"
)

func Handle(w http.ResponseWriter, r *http.Request) {
        var body []byte
        var sum float64 = 0

        //Gets function input
        if r.Body != nil {
            defer r.Body.Close()
            body, _=ioutil.ReadAll(r.Body)
        }

        // Parses input as a comma-separated list of numbers
        numbers := strings.Split(string(body), ",")

        //Tries to convert all values to numbers
        for _, number :=range numbers {
            number = strings.TrimSpace(number)
            if value, err :=strconv.ParserFloat(number, 32); err != nil {
                    //Throws an error if something is not a number
                    w.WriteHeader(http.StatusBadRequest)
                    w.Write([]byte("Invalid input format!"))
                    return
            } else {
                    sum += value
            }
        }

        w.WriterHeader(http.StatusOK)
        w.Write([]byte(fmt.Sprintf("%f", sum)))
}