Go Template学习2

创建一个web应用

使用html/template创建一个简单的web应用

工程文件结构如下:

webapp.png

使用到的包

// webapp
package main

import (
    "html/template"
    "log"
    "net/http"
    "strconv"
    "time"

    "github.com/gorilla/mux"
)

数据模型

type Note struct {
    Title       string
    Description string
    CreateOn    time.Time
}

main函数

func main() {
    r := mux.NewRouter().StrictSlash(false)
    fs := http.FileServer(http.Dir("public"))
    r.Handle("/public/", fs)
    r.HandleFunc("/", getNotes)
    r.HandleFunc("/notes/add", addNote)
    r.HandleFunc("/notes/save", saveNote)
    r.HandleFunc("/notes/edit/{id}", editNote)
    r.HandleFunc("/notes/update/{id}", updateNote)
    r.HandleFunc("/notes/delete/{id}", deleteNote)

    server := &http.Server{
        Addr:    ":9090",
        Handler: r,
    }
    log.Println("Listening...")
    server.ListenAndServe()
}

views 和模板文件


//base.html
{{define "base"}}

  {{template "head" .}}
  {{template "body" .}}

{{end}}

初始页面的模板
定义好的模板文件需要经过解析才能执行.解析文件只需要执行一次.执行的文件不需要每次都解析,这里的文件会被解析并且保存到一个字典中,以备后面调用.有三个HTML文件会被生成,所以map保存三个元素.定义好的模板会在init函数中使用Must方法解析.

var templates map[string]*template.Template

func init() {
    if templates == nil {
        templates = make(map[string]*template.Template)
    }

    templates["index"] = template.Must(template.ParseFiles("templates/index.html", "templates/base.html"))
    templates["add"] = template.Must(template.ParseFiles("templates/add.html", "templates/base.html"))
    templates["edit"] = template.Must(template.ParseFiles("templates/edit.html", "templates/base.html"))
}

//渲染模板的方法
func renderTemplate(w http.ResponseWriter, name string, template string, viewModel interface{}) {
    tmpl, ok := templates[name]
    if !ok {
        http.Error(w, "The template does not exist.", http.StatusInternalServerError)
    }
    err := tmpl.ExecuteTemplate(w, template, viewModel)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
    }

}

渲染index页面

//index.html
{{define "head"}}Index{{end}}

{{define "body"}}
Notes List

  Add Note



    
        {{range $key,$value := .}}

        
        {{end}}
    
        
            Title
            Description
            Create On
            Actions
        

            {{$value.Title}}
            {{$value.Description}}
            {{$value.CreateOn}}
            
                 Edit
                 Delete
            
        


{{end}}

Title	Description	Create On	Actions
{{$value.Title}}	{{$value.Description}}	{{$value.CreateOn}}	Edit Delete

在base.html定义好的模板名称:head和body,当index.html文件执行,元素是Note结构体的map会被传递.range 操作用来枚举map对象.在range操作下,两个定义好的变量key,value会被引用.一个range操作必须要用{{end}}来结束.

当我们访问路由 "/",会调用getNotes的请求handler,index页面会被渲染到浏览器,

func getNotes(w http.ResponseWriter, r *http.Request) {
    renderTemplate(w, "index", "base", noteStore)
}

渲染add添加页面

//add.html
{{define "head"}}Add Note{{end}}

{{define "body"}}
Add Note

  Title:

      
  
  Description:

       
  
  
      
  


{{end}}

//添加Note时的handler

func saveNote(w http.ResponseWriter, r *http.Request) {
    r.ParseForm()
    title := r.PostFormValue("title")
    desc := r.PostFormValue("description")
    note := Note{title, desc, time.Now()}
    id++

    k := strconv.Itoa(id)
    noteStore[k] = note
    http.Redirect(w, r, "/", 302)
}

渲染Edit编辑页面

//edit.html

{{define "head"}}
Edite Note
{{end}}

{{define "body"}}
Edit Note


  Title:

      
  
  Description:

      {{.Note.Description}}
  
  
      
  

{{end}}

//edit handler
func editNote(w http.ResponseWriter, r *http.Request) {
    var viewModel EditeNote
    vars := mux.Vars(r)
    k := vars["id"]

    if note, ok := noteStore[k]; ok {
        viewModel = EditeNote{note, k}
    } else {
        http.Error(w, "Could not find the resource to edit,", http.StatusBadRequest)
    }

    renderTemplate(w, "edit", "base", viewModel)
}

//更新Note的handler
func updateNote(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    k := vars["id"]
    var noteToUpd Note
    if note, ok := noteStore[k]; ok {
        r.ParseForm()
        noteToUpd.Title = r.PostFormValue("title")
        noteToUpd.Description = r.PostFormValue("description")
        noteToUpd.CreateOn = note.CreateOn
        delete(noteStore, k)
        noteStore[k] = noteToUpd

    } else {
        http.Error(w, "Could not find the resource to edit,", http.StatusBadRequest)
    }
    http.Redirect(w, r, "/", 302)
}

webapp.go代码

// webapp
package main

import (
    "html/template"
    "log"
    "net/http"
    "strconv"
    "time"

    "github.com/gorilla/mux"
)

type Note struct {
    Title       string
    Description string
    CreateOn    time.Time
}

type EditeNote struct {
    Note
    Id string
}

var noteStore = make(map[string]Note)
var id = 0
var templates map[string]*template.Template

func init() {
    if templates == nil {
        templates = make(map[string]*template.Template)
    }

    templates["index"] = template.Must(template.ParseFiles("templates/index.html", "templates/base.html"))
    templates["add"] = template.Must(template.ParseFiles("templates/add.html", "templates/base.html"))
    templates["edit"] = template.Must(template.ParseFiles("templates/edit.html", "templates/base.html"))
}

func renderTemplate(w http.ResponseWriter, name string, template string, viewModel interface{}) {
    tmpl, ok := templates[name]
    if !ok {
        http.Error(w, "The template does not exist.", http.StatusInternalServerError)
    }
    err := tmpl.ExecuteTemplate(w, template, viewModel)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
    }

}

func getNotes(w http.ResponseWriter, r *http.Request) {
    renderTemplate(w, "index", "base", noteStore)
}

func addNote(w http.ResponseWriter, r *http.Request) {
    renderTemplate(w, "add", "base", nil)
}

func saveNote(w http.ResponseWriter, r *http.Request) {
    r.ParseForm()
    title := r.PostFormValue("title")
    desc := r.PostFormValue("description")
    note := Note{title, desc, time.Now()}
    id++

    k := strconv.Itoa(id)
    noteStore[k] = note
    http.Redirect(w, r, "/", 302)
}

func editNote(w http.ResponseWriter, r *http.Request) {
    var viewModel EditeNote
    vars := mux.Vars(r)
    k := vars["id"]

    if note, ok := noteStore[k]; ok {
        viewModel = EditeNote{note, k}
    } else {
        http.Error(w, "Could not find the resource to edit,", http.StatusBadRequest)
    }

    renderTemplate(w, "edit", "base", viewModel)
}

func updateNote(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)
    k := vars["id"]
    var noteToUpd Note
    if note, ok := noteStore[k]; ok {
        r.ParseForm()
        noteToUpd.Title = r.PostFormValue("title")
        noteToUpd.Description = r.PostFormValue("description")
        noteToUpd.CreateOn = note.CreateOn
        delete(noteStore, k)
        noteStore[k] = noteToUpd

    } else {
        http.Error(w, "Could not find the resource to edit,", http.StatusBadRequest)
    }
    http.Redirect(w, r, "/", 302)
}

func deleteNote(w http.ResponseWriter, r *http.Request) {
    vars := mux.Vars(r)

    k := vars["id"]
    if _, ok := noteStore[k]; ok {
        delete(noteStore, k)
    } else {
        http.Error(w, "Could not find the resource to edit,", http.StatusBadRequest)
    }

    http.Redirect(w, r, "/", 302)
}

func main() {
    r := mux.NewRouter().StrictSlash(false)
    fs := http.FileServer(http.Dir("public"))
    r.Handle("/public/", fs)
    r.HandleFunc("/", getNotes)
    r.HandleFunc("/notes/add", addNote)
    r.HandleFunc("/notes/save", saveNote)
    r.HandleFunc("/notes/edit/{id}", editNote)
    r.HandleFunc("/notes/update/{id}", updateNote)
    r.HandleFunc("/notes/delete/{id}", deleteNote)

    server := &http.Server{
        Addr:    ":9090",
        Handler: r,
    }
    log.Println("Listening...")
    server.ListenAndServe()
}

小结:
在这个简单的例子,完整的使用Go的标准库创建了一个简单的web应用,动态数据渲染用户的界面.模板解析数据保存到一个字典中,这样可以轻松的获取到解析好的模板,在需要的时候.可以避免每次执行都解析模板,提升程序性能.

一些运行的截图:

![add2.png](http://upload-images.jianshu.io/upload_images/621082-659da0d146bebb96.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

get1.png

get2.png

Go Template学习2

创建一个web应用

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Add Note

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