This library offers a better approach toward the management of Go's built-in templates.
The goal is to be able to configure a set of root templates, presumably for a website, and then be able to render overrides as needed.
Run
go get github.com/kurrik/tmpl
Include in your source:
import "github.com/kurrik/tmpl"
See http://godoc.org/github.com/kurrik/tmpl
In the project root run:
go test
Start by defining a root template which contains placeholders for all referenced sub-templates. In the example, one file is used to hold all these but they could easily be split out into multiple files.
templates/root/root.tmpl
<html>
<head>{{template "head" .}}</head>
<body>{{template "body" .}}</body>
</html>
{{define "head"}}<title>{{.Title}}</title>{{end}}
{{define "body"}}{{end}}
Then define overrides which will be selectively used. For example, here is a post template which overrides body:
templates/post.tmpl
{{define "body"}}
<div>
<h2>{{.Title}}</h2>
<p>{{timeformat .Date "UnixDate"}}</p>
<p>{{.Body}}</p>
</div>
{{end}}
Note that it does not reside in the same directory as the root template, this allows us to parse the root template directory in a single command, and selectively use the post template override as needed.
Here's another body override which renders a list of posts:
templates/index.tmpl
{{define "body"}}
{{range .Posts}}
<div>
<h2>{{.Title}}</h2>
<p>{{timeformat .Date "UnixDate"}}</p>
<p>{{textcontent .Body}}</p>
</div>
{{end}}
{{end}}
To render templates call tmpl.NewTemplates and then parse the root template
structure. Since the example organized the root template into a directory,
this is as simple as calling AddTemplatesFromDir.
templates := tmpl.NewTemplates()
if err = templates.AddTemplatesFromDir("templates/root"); err != nil {
fmt.Printf("Error: %v\n", err)
return
}
Set up some sample data to render:
var (
out string
err error
)
post1 := map[string]interface{}{
"Title": "Hello World",
"Date": time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC),
"Body": "<em>Hi!</em>",
}
post2 := map[string]interface{}{
"Title": "Hello Again",
"Date": time.Date(2009, time.November, 10, 24, 0, 0, 0, time.UTC),
"Body": "<em>Hi there!</em>",
}
posts := map[string]interface{}{
"Title": "My Site",
"Posts": []map[string]interface{}{
post1,
post2,
},
}
Rendering templates is done by calling any of the RenderXXXX methods,
passing in override templates as needed. Here is the call to render the
index list of posts:
// Render the index.
if out, err = templates.RenderFile("templates/index.tmpl", posts); err != nil {
fmt.Printf("Error: %v\n", err)
} else {
fmt.Println("Index\n=============================")
fmt.Println(out)
}
This produces:
Index
=============================
<html>
<head><title>My Site</title></head>
<body>
<div>
<h2>Hello World</h2>
<p>Tue Nov 10 23:00:00 UTC 2009</p>
<p>Hi!</p>
</div>
<div>
<h2>Hello Again</h2>
<p>Wed Nov 11 00:00:00 UTC 2009</p>
<p>Hi there!</p>
</div>
</body>
</html>
Here is the call to render the first post:
// Render a post.
if out, err = templates.RenderFile("templates/post.tmpl", post1); err != nil {
fmt.Printf("Error: %v\n", err)
} else {
fmt.Println("Post\n=============================")
fmt.Println(out)
}
This produces:
Post
=============================
<html>
<head><title>Hello World</title></head>
<body>
<div>
<h2>Hello World</h2>
<p>Tue Nov 10 23:00:00 UTC 2009</p>
<p><em>Hi!</em></p>
</div>
</body>
</html>
You may also render a template string with the RenderText method:
// Render an ad-hoc template.
if out, err = templates.RenderText(`{{define "body"}}{{.Title}}{{end}}`, post1); err != nil {
fmt.Printf("Error: %v\n", err)
} else {
fmt.Println("Ad-hoc\n=============================")
fmt.Println(out)
}
This produces:
Ad-hoc
=============================
<html>
<head><title>Hello World</title></head>
<body>Hello World</body>
</html>
Some template functions are provided:
timeformat
This function takes a time.Time value as its first argument and renders
it according to a format string supplied as its second argument. If a string
is passed which matches a predefined format defined in the time package, that
format is used, otherwise it is treated as a literal format string:
{{timeformat .Date "UnixDate"}}
{{timeformat .Date "Mon Jan 02 15:04:05 -0700 2006"}}
textcontent This performs rudmentary stripping of HTML tags so that only text content is output. IMPORTANT! Do not use this method as a security measure - proper sanitization should be performed on untrusted input.
{{textcontent .Body}}