i18n: add the ability to register template funcs per locale

HISTORY.md

@@ -650,6 +650,7 @@ New Context Methods:
 
 Breaking Changes:
 
+- The `i18n#LoaderConfig.FuncMap template.FuncMap` field was replaced with `Funcs func(iris.Locale) template.FuncMap` in order to give current locale access to the template functions. A new `app.I18n.Loader` was introduced too, in order to make it easier for end-developers to customize the translation key values.
 - Request Logger's `Columns bool` field has been removed. Use the new [accesslog](https://github.com/kataras/iris/tree/master/_examples/logging/request-logger/accesslog/main.go) middleware instead.
 - The `.Binary` method of all view engines was removed: pass the go-bindata's latest version `AssetFile()` exported function as the first argument instead of string. All examples updated.
 - `ContextUploadFormFiles(destDirectory string, before ...func(*Context, *multipart.FileHeader) bool) (uploaded []*multipart.FileHeader, n int64, err error)` now returns the total files uploaded too (as its first parameter) and the "before" variadic option should return a boolean, if false then the specific file is skipped.

_examples/README.md

@@ -170,7 +170,8 @@
     * [Client-Side](compression/client/main.go)
     * [Client-Side (using Iris)](compress/client-using-iris/main.go)
 * Localization and Internationalization
-    * [i18n](i18n/main.go)
+    * [i18n](i18n)
+    * [i18n templates and functions](i18n/i18n-template)
 * Authentication, Authorization & Bot Detection 
     * [Basic Authentication](auth/basicauth/main.go)
     * [CORS](auth/cors)

_examples/i18n/i18n-template/main.go

@@ -1,12 +1,18 @@
 package main
 
 import (
-	"github.com/kataras/iris/v12"
+	"text/template"
 
+	"github.com/kataras/iris/v12"
 	// go get -u github.com/gertd/go-pluralize
 	"github.com/gertd/go-pluralize"
 )
 
+/*
+ Iris I18n supports text/template inside the translation values.
+ Follow this tutorial to learn how to use that feature.
+*/
+
 func main() {
 	app := newApp()
 	app.Listen(":8080")
@@ -16,18 +22,23 @@ func newApp() *iris.Application {
 	app := iris.New()
 
 	pluralize := pluralize.NewClient()
-	app.I18n.Loader.FuncMap = map[string]interface{}{
+
-		"plural": func(word string, count int) string {
+	// Set custom functions per locale!
-			// Your own implementation or use a 3rd-party package
+	app.I18n.Loader.Funcs = func(current iris.Locale) template.FuncMap {
-			// like we do here.
+		return template.FuncMap{
-			//
+			"plural": func(word string, count int) string {
-			// Note that this is only for english,
+				// Your own implementation or use a 3rd-party package
-			// but you can accept the language code
+				// like we do here.
-			// and use a map with dictionaries to
+				//
-			// pluralize words based on the given language.
+				// Note that this is only for english,
-			return pluralize.Pluralize(word, count, true)
+				// but you can accept the language code
-		},
+				// and use a map with dictionaries to
+				// pluralize words based on the given language.
+				return pluralize.Pluralize(word, count, true)
+			},
+		}
 	}
+
 	app.I18n.Load("./locales/*/*.yml", "en-US", "el-GR")
 
 	app.Get("/", func(ctx iris.Context) {

_examples/i18n/main.go

@@ -7,6 +7,10 @@ import (
 	"github.com/kataras/iris/v12"
 )
 
+/*
+	See i18n-template for a more advanced translation key-values.
+*/
+
 func newApp() *iris.Application {
 	app := iris.New()
 

aliases.go

@@ -159,6 +159,9 @@ type (
 	//
 	// An alias for the `context.N`.
 	N = context.N
+	// Locale describes the i18n locale.
+	// An alias for the `context.Locale`.
+	Locale = context.Locale
 )
 
 // Constants for input argument at `router.RouteRegisterRule`.

i18n/loader.go

@@ -26,8 +26,8 @@ type (
 	LoaderConfig struct {
 		// Template delimeters, defaults to {{ }}.
 		Left, Right string
-		// Template functions map, defaults to nil.
+		// Template functions map per locale, defaults to nil.
-		FuncMap template.FuncMap
+		Funcs func(context.Locale) template.FuncMap
 		// If true then it will return error on invalid templates instead of moving them to simple string-line keys.
 		// Also it will report whether the registered languages matched the loaded ones.
 		// Defaults to false.
@@ -43,17 +43,21 @@ type (
 
 // Apply implements the `LoaderOption` interface.
 func (c *LoaderConfig) Apply(cfg *LoaderConfig) {
-	for k, v := range c.FuncMap {
+	if c.Left != "" {
-		if cfg.FuncMap == nil {
+		cfg.Left = c.Left
-			cfg.FuncMap = make(template.FuncMap)
-		}
-
-		cfg.FuncMap[k] = v
 	}
 
-	cfg.Left = c.Left
+	if c.Right != "" {
-	cfg.Right = c.Right
+		cfg.Right = c.Right
-	cfg.Strict = c.Strict
+	}
+
+	if c.Funcs != nil {
+		cfg.Funcs = c.Funcs
+	}
+
+	if c.Strict {
+		cfg.Strict = true
+	}
 }
 
 // Glob accepts a glob pattern (see: https://golang.org/pkg/path/filepath/#Glob)
@@ -160,14 +164,22 @@ func load(assetNames []string, asset func(string) ([]byte, error), options ...Lo
 						// we assume it's template?
 						// each file:line has its own template funcs so,
 						// just map it.
-						builtinFuncs := template.FuncMap{
+
+						// builtin funcs.
+						funcs := template.FuncMap{
 							"tr": locale.GetMessage,
 						}
 
+						if c.Funcs != nil {
+							// set current locale's template's funcs.
+							for k, v := range c.Funcs(locale) {
+								funcs[k] = v
+							}
+						}
+
 						if t, err := template.New(k).
 							Delims(c.Left, c.Right).
-							Funcs(builtinFuncs).
+							Funcs(funcs).
-							Funcs(c.FuncMap).
 							Parse(value); err == nil {
 							templateKeys[k] = t
 							continue