封面.png
大家好，我叫谢伟，是一名程序员。
之前我推出了几个视频版的 golang 相关知识的讲解。看上去效果不好，毕竟简书作为写作平台，还是以阅读为主。
故以后的文章还是写出详细实例，最后再给出视频。各取所需吧。
本文的主题讲解：template 模板处理库
Package template implements data-driven templates for generating textual output.
即在MVC 设计模式的中View 层处理，html 文件中很多是静态数据，但也需要部分动态数据。template 库即是用来完成这个任务的, 即将动态数据填充入静态模板中。
机制如下：
My Name is {{ Name }}, you can call me {{ NickName }}
Name = xieWei
NickName = xiexiaolu
结果：
My Name is xiewei, you can call me xiexiaolu
在Go 语言中如何使用 template ?
1. 官方实例
package main
import (
"log"
"os"
"text/template"
)
func main() {
// Define a template.
const letter = `
Dear {{.Name}},
{{if .Attended}}
It was a pleasure to see you at the wedding.
{{- else}}
It is a shame you couldn't make it to the wedding.
{{- end}}
{{with .Gift -}}
Thank you for the lovely {{.}}.
{{end}}
Best wishes,
Josie
`
// Prepare some data to insert into the template.
type Recipient struct {
Name, Gift string
Attended bool
}
var recipients = []Recipient{
{"Aunt Mildred", "bone china tea set", true},
{"Uncle John", "moleskin pants", false},
{"Cousin Rodney", "", false},
}
// Create a new template and parse the letter into it.
t := template.Must(template.New("letter").Parse(letter))
// Execute the template for each recipient.
for _, r := range recipients {
err := t.Execute(os.Stdout, r)
if err != nil {
log.Println("executing template:", err)
}
}
}
结果：
Dear Aunt Mildred,
It was a pleasure to see you at the wedding.
Thank you for the lovely bone china tea set.
Best wishes,
Josie
Dear Uncle John,
It is a shame you couldn't make it to the wedding.
Thank you for the lovely moleskin pants.
Best wishes,
Josie
Dear Cousin Rodney,
It is a shame you couldn't make it to the wedding.
Best wishes,
Josie
Program exited.
2. 基本使用方法
1. 新建或者加载一个模板对象
type Template
func New(name string) *Template
func ParseFiles(filenames ...string) (*Template, error)
func Must(t *Template, err error) *Template
即：比如： t := template.New("test template")
2. 加载模板, 定义动态数据占位符
func (t *Template) Parse(text string) (*Template, error)
func (t *Template) ParseFiles(filenames ...string) (*Template, error)
即：比如
var templateText = `This is a test for template:
Name: {{.Name}}
Age: {{.Age}}
School: {{.School}}
Married: {{.MarriedOK}}
`
t, err = t.Parse(templateText)
3. 定义动态数据，执行
var example = struct {
Name string
Age int
School string
MarriedOK bool
}{
Name: "xiewei",
Age: 18,
School: "shanghaiUniversity",
MarriedOK: true,
}
t.Execute(os.Stdout, example)
结果：
This is a test for template
Name: xiewei
Age: 18
School: shanghaiUniversity
Married: true
3. 说明
1. 字段
-
{{.}}表示当前字段 -
{{.Name}}表示某个结构体的 Name 字段 - 结构体字段需能被外部访问：即 字段首字母大写
2. 循环操作
{{range .Field}}
{{.ChildFieldOne}} -- {{.ChildFieldTwo }}
{{ end }}
3. 判断
{{if .Field}} if部分的输出 {{else}} else 部分的输出 {{end}}
4. pipelines
即：处理经由前面一个指令传出的正确输出信息，对错误信息信息没有直接处理能力
管道符: |
{{.Field | html }}
5. 模板函数
即：可以对某个字段使用函数操作。适用于稍微复杂的字段处理。
type FuncMap map[string]interface{}
t = t.Funcs(template.FuncMap{"handleFieldName": HandleFunc})
内置模板函数：
var builtins = FuncMap{
"and": and,
"call": call,
"html": HTMLEscaper,
"index": index,
"js": JSEscaper,
"len": length,
"not": not,
"or": or,
"print": fmt.Sprint,
"printf": fmt.Sprintf,
"println": fmt.Sprintln,
"urlquery": URLQueryEscaper,
}
4. 示例
package main
import (
"fmt"
"html/template"
"os"
)
var Text = `
This is a test Template:
Name: {{.Name}}
Age:{{.Age}}
Married: {{.Married}}
School: {{.School}}
`
var TextTwo = `
This is a test Template:
Name: {{.Name |handleString | printf }}
Age: {{.Age | handleInt}}
Married: {{.Married }}
School: {{.School | handleString}}
`
var TextThree = `
{{if .Fields }}{{range .Fields }}
Name: {{.Name}} - Age:{{.Age}} - School:{{.School}} - Married:{{.Married}}
{{ end }}{{end}}
{{if .Names}}{{ range .Names }} {{.}} {{ end }}{{end}}
`
type Information struct {
Name string
Age int
Married bool
School string
}
func (this Information) String() string {
return fmt.Sprintf(`
This is a test String interface.
Name: %s
Age: %d
Married: %t
School: %s
`, this.Name, this.Age, this.Married, this.School)
}
func (this Information) Template(text string) {
var (
t *template.Template
)
t = template.New("New template for information")
var (
err error
)
if t, err = t.Parse(text); err != nil {
fmt.Println("Template parse err" + err.Error())
return
}
t.Execute(os.Stdout, this)
}
func (this Information) TemplateWithFuncMap(text string) {
var (
t *template.Template
err error
)
t = template.New("123").Funcs(InfoFuncMap())
//t = template.New("template with funcmap")
//t = t.Funcs(template.FuncMap{"handleString": handleString,
// "handleInt": handleInt})
if t, err = t.Parse(text); err != nil {
fmt.Println("err" + err.Error())
return
}
t.Execute(os.Stdout, this)
}
func InfoFuncMap() template.FuncMap {
return template.FuncMap{
"handleString": handleString,
"handleInt": handleInt,
}
}
func handleString(field string) string {
if field == "" {
return "None"
} else {
return " xiewei-test-for: " + field
}
}
func handleInt(number int) int {
return number + 20
}
type NewInformation struct {
Fields []Information
Names []string
}
func RangeTemplate(args NewInformation, text string) {
var (
t *template.Template
err error
)
t = template.New("new template")
if t, err = t.Parse(text); err != nil {
fmt.Println("err" + err.Error())
return
}
t.Execute(os.Stdout, args)
}
func main() {
var (
newInfor Information
)
newInfor = Information{
Name: "xiewei",
Age: 18,
School: "shanghaiUniversity",
Married: true,
}
fmt.Println("1")
fmt.Println(newInfor)
fmt.Println("2")
newInfor.Template(Text)
fmt.Println("3")
newInfor.TemplateWithFuncMap(TextTwo)
fmt.Println("4")
var (
newInformations NewInformation
)
newInformations = NewInformation{
Fields: []Information{
Information{Name: "xiexiaolu", Age: 19, Married: false, School: "pekingUniversity"},
Information{Name: "xiexie", Age: 20, Married: true, School: "XXXXX"},
},
Names: []string{
"jiewu", "baidu", "google", "aiqiyi", "wangyi",
},
}
RangeTemplate(newInformations, TextThree)
}
结果：
1
This is a test String interface.
Name: xiewei
Age: 18
Married: true
School: shanghaiUniversity
2
This is a test Template:
Name: xiewei
Age:18
Married: true
School: shanghaiUniversity
3
This is a test Template:
Name: xiewei-test-for: xiewei
Age: 38
Married: true
School: xiewei-test-for: shanghaiUniversity
4
Name: xiexiaolu - Age:19 - School:pekingUniversity - Married:false
Name: xiexie - Age:20 - School:XXXXX - Married:true
jiewu baidu google aiqiyi wangyi
5. 视频
唉 , 我好像英文发音不准叻。我会注意的。
6. 开源库处理方式
- beego --> bee
func Tmpl(text string, data interface{}) {
output := colors.NewColorWriter(os.Stderr)
t := template.New("Usage").Funcs(BeeFuncMap())
template.Must(t.Parse(text))
err := t.Execute(output, data)
if err != nil {
beeLogger.Log.Error(err.Error())
}
}
func BeeFuncMap() template.FuncMap {
return template.FuncMap{
"trim": strings.TrimSpace,
"bold": colors.Bold,
"headline": colors.MagentaBold,
"foldername": colors.RedBold,
"endline": EndLine,
"tmpltostr": TmplToString,
}
}
var usageTemplate = `Bee is a Fast and Flexible tool for managing your Beego Web Application.
{{"USAGE" | headline}}
{{"bee command [arguments]" | bold}}
{{"AVAILABLE COMMANDS" | headline}}
{{range .}}{{if .Runnable}}
{{.Name | printf "%-11s" | bold}} {{.Short}}{{end}}{{end}}
Use {{"bee help [command]" | bold}} for more information about a command.
{{"ADDITIONAL HELP TOPICS" | headline}}
{{range .}}{{if not .Runnable}}
{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
Use {{"bee help [topic]" | bold}} for more information about that topic.
`
var AppHelpTemplate = `NAME:
{{.Name}}{{if .Usage}} - {{.Usage}}{{end}}
USAGE:
{{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} {{if .VisibleFlags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Version}}{{if not .HideVersion}}
VERSION:
{{.Version}}{{end}}{{end}}{{if .Description}}
DESCRIPTION:
{{.Description}}{{end}}{{if len .Authors}}
AUTHOR{{with $length := len .Authors}}{{if ne 1 $length}}S{{end}}{{end}}:
{{range $index, $author := .Authors}}{{if $index}}
{{end}}{{$author}}{{end}}{{end}}{{if .VisibleCommands}}
COMMANDS:{{range .VisibleCategories}}{{if .Name}}
{{.Name}}:{{end}}{{range .VisibleCommands}}
{{join .Names ", "}}{{"\t"}}{{.Usage}}{{end}}{{end}}{{end}}{{if .VisibleFlags}}
GLOBAL OPTIONS:
{{range $index, $option := .VisibleFlags}}{{if $index}}
{{end}}{{$option}}{{end}}{{end}}{{if .Copyright}}
COPYRIGHT:
{{.Copyright}}{{end}}
`
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