add an app.View example for parsing and writing templates outside of the HTTP scope(context.View)

Former-commit-id: e65d8ece521c778dedf45cf2f522383c26b9901b

_examples/README.md

@@ -294,7 +294,7 @@ Follow the examples below,
 - [The `url` tmpl func](view/template_html_4/main.go)
 - [Inject Data Between Handlers](view/context-view-data/main.go)
 - [Embedding Templates Into App Executable File](view/embedding-templates-into-app/main.go)
-
+- [Write to a custom `io.Writer`](view/write-to)
 
 You can serve [quicktemplate](https://github.com/valyala/quicktemplate) and [hero templates](https://github.com/shiyanhui/hero/hero) files too, simply by using the `context#ResponseWriter`, take a look at the [http_responsewriter/quicktemplate](http_responsewriter/quicktemplate) and [http_responsewriter/herotemplate](http_responsewriter/herotemplate) examples.
 

_examples/view/write-to/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"os"
+
+	"github.com/kataras/iris"
+)
+
+type mailData struct {
+	Title    string
+	Body     string
+	RefTitle string
+	RefLink  string
+}
+
+func main() {
+	app := iris.New()
+	app.Logger().SetLevel("debug")
+	app.RegisterView(iris.HTML("./views", ".html"))
+
+	// you need to call `app.Build` manually before using the `app.View` func,
+	// so templates are built in that state.
+	app.Build()
+
+	// Or a string-buffered writer to use its body to send an e-mail
+	// for sending e-mails you can use the https://github.com/kataras/go-mailer
+	// or any other third-party package you like.
+	//
+	// The template's parsed result will be written to that writer.
+	writer := os.Stdout
+	err := app.View(writer, "email/simple.html", "shared/email.html", mailData{
+		Title:    "This is my e-mail title",
+		Body:     "This is my e-mail body",
+		RefTitle: "Iris web framework",
+		RefLink:  "https://iris-go.com",
+	})
+
+	if err != nil {
+		app.Logger().Errorf("error from app.View: %v", err)
+	}
+
+	app.Run(iris.Addr(":8080"))
+}

_examples/view/write-to/views/email/simple.html

@@ -0,0 +1 @@
+{{.Body}}

_examples/view/write-to/views/shared/email.html

@@ -0,0 +1,6 @@
+<h1>{{.Title}}</h1>
+<p class="body">
+    {{yield}}
+</p>
+
+<a href="{{.RefLink}}" target="_new">{{.RefTitle}}</a>