How to Resolve 'function not defined' Errors When Parsing Go Templates with Custom Functions?

Parsing Templates with Custom Functions in Go

Custom functions need to be registered before parsing templates in Go. When attempting to access an unregistered function, you may encounter an error like:

Error: template: struct.tpl:3: function "makeGoName" not defined

To resolve this issue, create a new, undefined template using template.New(). The template.Template type returned by template.New() has a Template.ParseFiles() method that should be used instead of template.ParseFiles().

Here's an example:

t, err := template.New("struct.tpl").Funcs(template.FuncMap{
    "makeGoName": makeGoName,
    "makeDBName": makeDBName,
}).ParseFiles("templates/struct.tpl")

When using template.ParseFiles(), you must specify the basename of the file being executed in template.New().

Remember, Template.Execute() also returns an error. If no output is generated, print the error:

if err := t.Execute(os.Stdout, data); err != nil {
    fmt.Println(err)
}

The above is the detailed content of How to Resolve 'function not defined' Errors When Parsing Go Templates with Custom Functions?. For more information, please follow other related articles on the PHP Chinese website!