Template

這也太神奇惹吧XD，印象中 Hugo (?!) 有看過這樣的寫法

Remark

直接插入 data：{{.}}

struct 寫法，後面要加入欄位：{{.field}}

true 才會顯示中間的 data：{{if .}}xxx{{end}}

迴圈：{{range .}}{{.}}{{end}}

Example

Template

package main

import (
    "log"
    "os"
    "text/template"
)

func main() {
    // {{.}}
    exeTemplate("i am not a {{.}} guy\n", "C#")
    exeTemplate("i am a {{.}} guy\n", "Go")

    // {{if .}}xxx{{end}}
    exeTemplate("{{if .}}i like Go{{end}}\n", true)
    exeTemplate("{{if .}}i like C#{{end}}\n", false)

    // {{range .}}{{.}}{{end}}
    exeTemplate("{{range .}}i am a {{.}} guy\n{{end}}\n", []string{"Go", "Java", "Python"})

    // {{.field}} struct 寫法
    exeTemplate("{{.Name}} language's salary is {{.Salary}}K.{{if .IsPopular}} Besides, it's very popular.{{end}}\n",
        Language{Name: "Go", Salary: 121, IsPopular: true})
}

func exeTemplate(text string, data interface{}) {
    tmpl, err := template.New("test").Parse(text)
    check(err)
    err = tmpl.Execute(os.Stdout, data) // Stdout (standard output) -> terminal
    check(err)
}

func check(err error) {
    if err != nil {
        log.Fatal(err)
    }
}

type Language struct {
    Name      string
    Salary    int
    IsPopular bool
}

簽到簿應用程式

• main.go

package main

import (
    "bufio"
    "fmt"
    "html/template"
    "log"
    "net/http"
    "os"
)

func main() {
    http.HandleFunc("/guestbook", viewHandler)
    http.HandleFunc("/guestbook/new", newHandler)
    http.HandleFunc("/guestbook/create", createHandler)
    err := http.ListenAndServe(":8080", nil)
    log.Fatal(err)
}

func viewHandler(writer http.ResponseWriter, request *http.Request) {
    signatures := getSignatures("signatures.txt")
    tmpl, err := template.ParseFiles("view.html")
    check(err)

    guestBook := GuestBook{SignatureCount: len(signatures), Signatures: signatures}
    err = tmpl.Execute(writer, guestBook)
    check(err)
}

func newHandler(writer http.ResponseWriter, request *http.Request) {
    tmpl, err := template.ParseFiles("new.html")
    check(err)
    err = tmpl.Execute(writer, nil)
    check(err)
}

func createHandler(writer http.ResponseWriter, request *http.Request) {
    signature := request.FormValue("signature")

    // OR 位元運算子
    options := os.O_WRONLY | os.O_APPEND | os.O_CREATE

    file, err := os.OpenFile("signatures.txt", options, os.FileMode(0600))
    check(err)
    _, err = fmt.Fprintln(file, signature)
    check(err)
    err = file.Close()
    check(err)

    http.Redirect(writer, request, "/guestbook", http.StatusFound)
}

type GuestBook struct {
    SignatureCount int
    Signatures     []string
}

func getSignatures(fileName string) []string {
    var result []string

    file, err := os.Open(fileName)
    if os.IsNotExist(err) {
        return nil
    }
    check(err)
    defer file.Close()
    scanner := bufio.NewScanner(file)
    for scanner.Scan() {
        result = append(result, scanner.Text())
    }
    check(scanner.Err())
    return result
}

func check(err error) {
    if err != nil {
        log.Fatal(err)
    }
}

• view.html

<h1>Guestbook</h1>

<div>
  {{.SignatureCount}} total signature -
  <a href="/guestbook/new">Add Your Signature</a>
</div>

<div>
  {{range .Signatures}}
  <p>{{.}}</p>
  {{end}}
</div>

• new.html

<h1>Add a Signature</h1>

<form action="/guestbook/create" method="post">
  <div><input type="text" name="signature" id="" /></div>
  <div><input type="submit" /></div>
</form>