英文:
Pulling model directly from Revel template engine
问题
在Go/Revel的模板中，可以像在erb文件中那样直接从视图中获取模型数据吗？例如：
<script>
var vm = {
rows: {{ .ModelName.Rows | jsonify }}
};
// 使用客户端JavaScript渲染vm.rows
</script>
<div>
bla bla
</div>
在Go/Revel的模板中，使用双大括号{{ }}来包裹模型数据，并使用管道符号|来调用相应的函数或过滤器。在上面的示例中，我们使用了.ModelName.Rows来获取模型数据，并使用jsonify过滤器将其转换为JSON格式。然后，我们将结果赋值给JavaScript变量vm.rows，以便在客户端使用JavaScript进行渲染。
英文:
I come from Ruby/PHP background, usually I use pull the model from the View directly without controller, for example inside an erb file:
<script>
var vm = {
rows: <%= ModelName.rows.to_json %>
};
// render vm.rows using client-side javascript
</script>
<div>
bla bla
</div>
Is it possible to pull model just like what I did in erb, inside Go/Revel's template?
答案1
得分: 2
将代码直接嵌入模板的方法只适用于解释型语言，如Ruby和PHP。Go模板包支持一些简单的指令（如if、else、range等-详见这里），但这种语法远远不及完整的脚本语言-这可能也不是预期的。你可以从模板中调用诸如to_json方法之类的方法。然而（正如twotwotwo正确指出的那样），你甚至可能不需要额外的方法将数据转换为JSON-如果将其放置在<script>标签之间，Go会自动进行转换。要自定义转换，请实现Marshaler接口，提供一个MarshalJSON方法，如这里所述。
以下示例演示了直接输出结构体，在“script”上下文中使用方法：
package main
import (
"html/template"
"log"
"os"
"strings"
)
type Greeter struct {
Repeat int
Salutation string
}
func (g Greeter) Perform() string {
return strings.Repeat(g.Salutation+" ", g.Repeat)
}
func main() {
sayHi := Greeter{Repeat: 3, Salutation: "Hi!"}
tmpl, err := template.New("").Parse("{{.}}\n<script>{{.}}</script>\n{{.Perform}}")
if err != nil {
log.Fatalf("Parse: %v", err)
}
tmpl.Execute(os.Stdout, sayHi)
}
输出：
{3 Hi!}
<script>{"Repeat":3,"Salutation":"Hi!"}</script>
Hi! Hi! Hi!
Revel是基于Go模板包构建的，而不是实现自己的模板系统，因此上述内容也适用于Revel。
英文:
This method of embedding code directly into a template can only be done with interpreted languages such as Ruby and PHP. The Go template packages support some simple instructions (if, else, range etc. - see here for details) but this syntax doesn't come close to a full scripting language - that's probably not intended either. You can call methods such as your to_json method from templates. However (as twotwotwo rightfully pointed out) you may not even need an extra method to convert your data to JSON - if you place it between <script> tags, Go will do the conversion by itself. To customize the conversion, implement the Marshaler interface by providing a MarshalJSON method as described here.
The following example demonstrates outputting a struct directly, in a "script" context and using a method:
package main
import (
"html/template"
"log"
"os"
"strings"
)
type Greeter struct {
Repeat int
Salutation string
}
func (g Greeter) Perform() string {
return strings.Repeat(g.Salutation+" ", g.Repeat)
}
func main() {
sayHi := Greeter{Repeat: 3, Salutation: "Hi!"}
tmpl, err := template.New("").Parse("{{.}}\n<script>{{.}}</script>\n{{.Perform}}")
if err != nil {
log.Fatalf("Parse: %v", err)
}
tmpl.Execute(os.Stdout, sayHi)
}
http://play.golang.org/p/f3HShZfd6H
Output:
{3 Hi!}
<script>{"Repeat":3,"Salutation":"Hi!"}</script>
Hi! Hi! Hi!
Revel builds on the Go template packages rather than implementing its own template system, so the above applies to Revel as well.
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