Use Scratch function get global variable in partial template.

layouts/partials/head/open_graph.html

@@ -1,9 +1,9 @@
 {{- $Site := .Site -}}
 {{- $Params := .Site.Params -}}
 {{- $Page := .Page -}}
+{{- $langCode := .Scratch.Get "langCode" -}}
 {{- with .Site.Params.openGraph -}}
 {{- if .enable -}}
-{{- $langCode := replaceRE "-([a-z]+)" (upper (substr $Site.Language -3)) $Site.Language }}
   <meta property="og:type" content="website">
   <meta property="og:title" content="{{ $Page.Title }}">
   <meta property="og:description" content="{{ default $Params.description $Page.Description }}">
@@ -12,7 +12,6 @@
   <meta property="og:site_name" content="{{ $Site.Title }}">
   <meta property="og:locale" content="{{ $langCode }}">
   <meta property="article:author" content="{{ default $Params.author $Page.Params.Author }}">
-
 {{- with .twitter -}}
 {{- range $attr, $val := . }}
   <meta name="twitter:{{ $attr }}" content="{{ $val }}">