内存错误，Go中的html / template

Question

I get some memory error when trying to execute this code:

package web

import (
    "net/http"
    "html/template"
)

type Hello struct {
    Level string
}

func Main(w http.ResponseWriter, r *http.Request) {

    h := Hello{Level: "gsdfg"}

    t, _ := template.ParseFiles("web.html")
    t.Execute(w, h)
}

The error message I get in the browser is this:

the runtime process gave a bad HTTP response: ''

2015/03/26 11:34:56 http: panic serving 127.0.0.1:43269: runtime error: invalid memory address or nil pointer dereference

I dont understand what I am doing wrong...

Answer 1

template.ParseFiles returns an error

func ParseFiles(filenames ...string) (*Template, error)

If an error occurs, parsing stops and the returned *Template is nil.

You should check the error in case there is an issue.
That could explain why 't' might be nil.

In general, the best practice is to never ignore error.

Here:

var t *Template
if t, err := template.ParseFiles("web.html"); err != nil {
    // do something
    // return err
    // or
    // panic(err)
}