diff options
Diffstat (limited to 'doc/codelab/wiki/index.html')
| -rw-r--r-- | doc/codelab/wiki/index.html | 60 |
1 files changed, 32 insertions, 28 deletions
diff --git a/doc/codelab/wiki/index.html b/doc/codelab/wiki/index.html index cc187ad90..50e9db5e9 100644 --- a/doc/codelab/wiki/index.html +++ b/doc/codelab/wiki/index.html @@ -429,7 +429,9 @@ Of course, there is a better way. <h2>The <code>template</code> package</h2> <p> -The <code>template</code> package is part of the Go standard library. We can +The <code>template</code> package is part of the Go standard library. +(A new template package is coming; this code lab will be updated soon.) +We can use <code>template</code> to keep the HTML in a separate file, allowing us to change the layout of our edit page without modifying the underlying Go code. @@ -454,10 +456,10 @@ Open a new file named <code>edit.html</code>, and add the following lines: </p> <pre> -<h1>Editing {Title}</h1> +<h1>Editing {{.Title |html}}</h1> -<form action="/save/{Title}" method="POST"> -<div><textarea name="body" rows="20" cols="80">{Body|html}</textarea></div> +<form action="/save/{{.Title |html}}" method="POST"> +<div><textarea name="body" rows="20" cols="80">{{printf "%s" .Body |html}}</textarea></div> <div><input type="submit" value="Save"></div> </form> </pre> @@ -474,7 +476,7 @@ func editHandler(w http.ResponseWriter, r *http.Request) { if err != nil { p = &Page{Title: title} } - t, _ := template.ParseFile("edit.html", nil) + t, _ := template.ParseFile("edit.html") t.Execute(w, p) } </pre> @@ -485,19 +487,21 @@ The function <code>template.ParseFile</code> will read the contents of </p> <p> -The method <code>t.Execute</code> replaces all occurrences of -<code>{Title}</code> and <code>{Body}</code> with the values of -<code>p.Title</code> and <code>p.Body</code>, and writes the resultant -HTML to the <code>http.ResponseWriter</code>. +The method <code>t.Execute</code> executes the template, writing the +generated HTML to the <code>http.ResponseWriter</code>. +The <code>.Title</code> and <code>.Body</code> dotted identifiers refer to +<code>p.Title</code> and <code>p.Body</code>. </p> <p> -Note that we've used <code>{Body|html}</code> in the above template. -The <code>|html</code> part asks the template engine to pass the value -<code>Body</code> through the <code>html</code> formatter before outputting it, -which escapes HTML characters (such as replacing <code>></code> with -<code>&gt;</code>). -This will prevent user data from corrupting the form HTML. +Template directives are enclosed in double curly braces. +The <code>printf "%s" .Body</code> instruction is a function call +that outputs <code>.Body</code> as a string instead of a stream of bytes, +the same as a call to <code>fmt.Printf</code>. +The <code>|html</code> part of each directive pipes the value through the +<code>html</code> formatter before outputting it, which escapes HTML +characters (such as replacing <code>></code> with <code>&gt;</code>), +preventing user data from corrupting the form HTML. </p> <p> @@ -511,11 +515,11 @@ While we're working with templates, let's create a template for our </p> <pre> -<h1>{Title}</h1> +<h1>{{.Title |html}}</h1> -<p>[<a href="/edit/{Title}">edit</a>]</p> +<p>[<a href="/edit/{{.Title |html}}">edit</a>]</p> -<div>{Body}</div> +<div>{{printf "%s" .Body |html}}</div> </pre> <p> @@ -526,7 +530,7 @@ Modify <code>viewHandler</code> accordingly: func viewHandler(w http.ResponseWriter, r *http.Request) { title := r.URL.Path[lenPath:] p, _ := loadPage(title) - t, _ := template.ParseFile("view.html", nil) + t, _ := template.ParseFile("view.html") t.Execute(w, p) } </pre> @@ -706,16 +710,17 @@ var templates = make(map[string]*template.Template) <p> Then we create an <code>init</code> function, which will be called before <code>main</code> at program initialization. The function -<code>template.MustParseFile</code> is a convenience wrapper around -<code>ParseFile</code> that does not return an error code; instead, it panics -if an error is encountered. A panic is appropriate here; if the templates can't -be loaded the only sensible thing to do is exit the program. +<code>template.Must</code> is a convenience wrapper that panics when passed a +non-nil <code>os.Error</code> value, and otherwise returns the +<code>*Template</code> unaltered. A panic is appropriate here; if the templates +can't be loaded the only sensible thing to do is exit the program. </p> <pre> func init() { for _, tmpl := range []string{"edit", "view"} { - templates[tmpl] = template.MustParseFile(tmpl+".html", nil) + t := template.Must(template.ParseFile(tmpl + ".html")) + templates[tmpl] = t } } </pre> @@ -761,10 +766,9 @@ var titleValidator = regexp.MustCompile("^[a-zA-Z0-9]+$") <p> The function <code>regexp.MustCompile</code> will parse and compile the regular expression, and return a <code>regexp.Regexp</code>. -<code>MustCompile</code>, like <code>template.MustParseFile</code>, -is distinct from <code>Compile</code> in that it will panic if -the expression compilation fails, while <code>Compile</code> returns an -<code>os.Error</code> as a second parameter. +<code>MustCompile</code> is distinct from <code>Compile</code> in that it will +panic if the expression compilation fails, while <code>Compile</code> returns +an <code>os.Error</code> as a second parameter. </p> <p> |