Golang 模板(并将函数传递给模板) [英] Golang templates (and passing funcs to template)
问题描述
当我尝试访问传递给模板的函数时出现错误:
I'm getting an error when I try and access a function I'm passing to my template:
Error: template: struct.tpl:3: function "makeGoName" not defined
谁能告诉我我做错了什么?
Can anyone please let me know what I'm doing wrong?
模板文件(struct.tpl):
Template file (struct.tpl):
type {{.data.tableName}} struct {
{{range $key, $value := .data.tableData}}
{{makeGoName $value.colName}} {{$value.colType}} `db:"{{makeDBName $value.dbColName}},json:"{{$value.dbColName}}"`
{{end}}
}
调用文件:
type tplData struct {
tableName string
tableData interface{}
}
func doStuff() {
t, err := template.ParseFiles("templates/struct.tpl")
if err != nil {
errorQuit(err)
}
t = t.Funcs(template.FuncMap{
"makeGoName": makeGoName,
"makeDBName": makeDBName,
})
data := tplData{
tableName: tableName,
tableData: tableInfo,
}
t.Execute(os.Stdout, data)
}
func makeGoName(name string) string {
return name
}
func makeDBName(name string) string {
return name
}
这是用于生成结构样板代码的程序(以防有人想知道我为什么要在模板中这样做).
This is for a program that generates struct boilerplate code (in case anyone is wondering why I'm doing that in my template).
推荐答案
在解析模板之前需要注册自定义函数,否则解析器将无法判断标识符是否是有效的函数名称.模板被设计为可静态分析的,这是对模板的要求.
Custom functions need to be registered before parsing the templates, else the parser would not be able to tell whether an identifier is a valid function name or not. Templates are designed to be statically analyzable, and this is a requirement to that.
您可以首先使用 template.New()<创建一个新的未定义模板/code>
,除了 template.ParseFiles()
功能,template.Template
类型(由 New()
返回)也有一个 Template.ParseFiles()
方法,你可以调用它.
You can first create a new, undefined template with template.New()
, and besides the template.ParseFiles()
function, the template.Template
type (returned by New()
) also has a Template.ParseFiles()
method, you can call that.
像这样:
t, err := template.New("").Funcs(template.FuncMap{
"makeGoName": makeGoName,
"makeDBName": makeDBName,
}).ParseFiles("templates/struct.tpl")
请注意,template.ParseFiles()
函数还在后台调用了 template.New()
,将第一个文件的名称作为模板名称传递.
Note that the template.ParseFiles()
function also calls template.New()
under the hood, passing the name of the first file as the template name.
还有 Template.Execute()
返回一个 error
,打印出来看看是否没有输出,例如:
Also Template.Execute()
returns an error
, print that to see if no output is generated, e.g.:
if err := t.Execute(os.Stdout, data); err != nil {
fmt.Println(err)
}
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