【RazorEngine】套寄信、罐頭訊息內容的好幫手

本篇使用套件 : RazorEngine   【官方文件 】

遙想當年巷口寶之林還開著時，我這鄉野村夫每每需要套Email寄信格式以及一些罐頭訊息時，總是串一堆字串，既醜又難維護

public ActionResult Test(string name)
        {

            var sb = new StringBuilder();
            sb.AppendLine(string.Format(@"Hello {0}, welcome to RazorEngine!",name));

            return Content(sb.ToString());
        }

如果碰到麻煩一點的，像是什麼狀況要套表頭，某某狀況又要移除Footer，那整個字串的邏輯東拼西湊，最後不執行根本難以看出結果會變成如何，往往就變成維護的黑洞跟死角誰接手誰倒楣。

自從我認識了RazorEngine這套件後，世界就變美好了，只要你會套.Net MVC的View，那基本上這個套件絕對是適合你的神兵利器，廢話不多說，我們先來將剛剛版本改成用RazorEngine處理

先去Nuget安裝套件

[](https://3.bp.blogspot.com/-C5_gHPnJWEc/Wl64J_9mh5I/AAAAAAAAISA/GiHxPzZP9Qs9OyY_eVI4FrxHeD7MELXxQCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

套上RazorEngine後，可以改成這樣

public ActionResult TestRazorEngine(string name)
        {
            string template = "Hello @Model.Name, welcome to RazorEngine!";

            var Result = Engine.Razor.RunCompile(
                            templateSource: template,
                            name: "HelloWorldTemplateKey", 
                            modelType: null,
                            model: new { Name = name });

            return Content(Result);
        }

這邊解說一下程式碼，RazorEnginr提供了幾種方法來產生編譯過的Template，分別是

**Run **: 依據帶入的Name去尋找Cache中是否有編譯過的Template，如果Cache沒有這個Name的模板，則會跳Exception

**Compile **: 將帶入的模板內容編譯，並存進Cache

**RunCompile **: 等於上面兩者個結合，先去Cache中找看看有無這個Name的模板，有則直接回傳，沒有則先編譯後存入Cache，並回傳

依據官方文件所提到的，Compile Template是很耗效能的，所以建議都要存入Cache，避免每次去Compile(預設行為就是如此，當然之後也會提到如何改寫)

有了初步的認識後，應該會發現目前的做法跟拼湊字串一樣，如果只是這樣也就失去了使用RazorEngine的意義了，所以下一步是將這個Template內容變成.cshtml，可以大大的增加可讀性跟維護姓

[](https://3.bp.blogspot.com/-pfz4iweMebY/Wl68R2ISmxI/AAAAAAAAISM/aEjP8lgBlY0krsOinpRLB1Q88251KecqQCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

新增_HelloWorld.cshtml Template

將剛剛的字串貼進去，並且就像我們一般套版一樣，建立對應的ViewModel

[](https://2.bp.blogspot.com/-cEGoNuCIBPc/Wl68rMWc_6I/AAAAAAAAISQ/wECO1yhBn2My81LPW3lK9aKo9QfXMHnOACLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

public class HellowWorldRazorModel
    {
        public string Name { get; set; }
    }

原本的程式碼改寫成如下

public ActionResult TestRazorEngine(string name)
        {
            var Result =  Engine.Razor.RunCompile(
                            "_HelloWorld", 
                            typeof(HellowWorldRazorModel), 
                            new HellowWorldRazorModel { Name = name });

            return Content(Result);
        }

但執行之後就會出Exception，原因是”_HelloWorld”這個Template Name它不知道怎麼對應到哪個cshtml模板

[](https://4.bp.blogspot.com/-8LQ2IYJBnmI/Wl6-F94TFFI/AAAAAAAAISg/FuId2F7jKVYBpu3wOMLY1UPSkOY2P5E2QCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

所以我們要自己寫RazorEngine的ITemplateManager :  官方文件參考

public class MyTemplateManager : ITemplateManager
    {
        public ITemplateSource Resolve(ITemplateKey key)
        {
            // Resolve your template here (ie read from disk)
            // if the same templates are often read from disk you propably want to do some caching here.
            var template = Tools.ChkCache(key.Name) as string;
            if (string.IsNullOrWhiteSpace(template))
            {
                var FilePath = string.Format("~/Views/RazorTemplate/{0}.cshtml", key.Name);
                template = File.ReadAllText(HttpContext.Current.Server.MapPath(FilePath));

                Tools.SaveToCache(key.Name, template, 3600, CacheType.Absolute, null);
            }
            // Provide a non-null file to improve debugging
            return new LoadedTemplateSource(template, null);
        }

        public ITemplateKey GetKey(string name, ResolveType resolveType, ITemplateKey context)
        {
            // If you can have different templates with the same name depending on the 
            // context or the resolveType you need your own implementation here!
            // Otherwise you can just use NameOnlyTemplateKey.
            return new NameOnlyTemplateKey(name, resolveType, context);
            // template is specified by full path
            //return new FullPathTemplateKey(name, fullPath, resolveType, context);
        }

        public void AddDynamic(ITemplateKey key, ITemplateSource source)
        {
            // You can disable dynamic templates completely. 
            // This just means all convenience methods (Compile and RunCompile) with
            // a TemplateSource will no longer work (they are not really needed anyway).
            throw new NotImplementedException("dynamic templates are not supported!");
        }
    }

這邊我只改寫Resolve這個方法，其他都沿用官方文件的範本，內容只要是依據帶入的Name去確認Cache是否已經有Template(因為用公司的底層套件，所以確認Cache跟Save Cache可能跟一般認知的方法不同，請忽略或用.Net提供的Cache方法即可)，如果沒有快取，則依據帶入的Name去對應的Folder位置讀取.cshtml並且Cache，然後透過RazorEngine提供的方法LoadedTemplateSource回傳TemplateSource。

這一段可以讓RazorEngine知道如何將Name對應到我們的cshtml，寫完客製的MyTemplateManager後接著是設定

Global.asax加上這段

protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            //RazorEngine Setting
            var config = new TemplateServiceConfiguration();
            config.TemplateManager = new MyTemplateManager();

            var service = RazorEngineService.Create(config);
            Engine.Razor = service;
        }

接著剛剛的程式就能執行了!!

[](https://3.bp.blogspot.com/-NWxWGypeAdo/Wl7AVFb9jRI/AAAAAAAAISs/24bA9qjOkTwoY1ca8SDc8_OXhuB3vI_2QCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

RazorEngine也提供Layout的套版方法，可以在cshmtl上面設定對應的Layout，不用像先前提到的，拼字串拼得亂七八糟了

[](https://3.bp.blogspot.com/-lOts6puSj9Q/Wl7BYAAbwJI/AAAAAAAAIS0/E05MfohLLpgG0Cp2x63uJ8i6ZL-ifJdagCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

新增_OurLayout.cshmtl

[](https://3.bp.blogspot.com/-e3Q9NSlCVuk/Wl7Bsff9odI/AAAAAAAAIS4/J0XN1F7PPW0rqsRmvA9yw5cGcTeAjJiawCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

Layout的內容

[](https://3.bp.blogspot.com/-ugzdMhXnb3w/Wl7CFh0QMAI/AAAAAAAAITA/yxDlQmxK1f4X_4zjamWyCEJnoTUWgwfkgCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

執行結果

[](https://1.bp.blogspot.com/-t8lTrthvFXQ/Wl7CXvDYDMI/AAAAAAAAITE/k4aTtPG7zsIUmvUG4U5hvI7nyOpV6JzmACLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

RazorEngine PartialView的用法

在一般套版，我們可能會把共用的區塊挖成PartialView重複使用，但這邊的用法比較特別，須改用Include這個方法取代

[](https://4.bp.blogspot.com/-m5NwrfUZcMs/Wl7C11d-lnI/AAAAAAAAITM/AA-QS-UbaEgFXr8MUjx3olooVMgAEkLbwCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

新增PartialView

[](https://1.bp.blogspot.com/-NvEYUWh1nkw/Wl7DBfTkNOI/AAAAAAAAITQ/SBSCU6uWL2ck3U7nncXsEo4q5mdRFboiQCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

PartialView的內容，而且也可以使用ViewBag傳遞參數

[](https://1.bp.blogspot.com/-Ll9MHoSaYtM/Wl7Dk_WcOGI/AAAAAAAAITY/8CF1z0SXs2M21_tS3YCH5KrEY6WP6zAAgCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

改寫原本的_HelloWorld.cshtml，套入PartialView

執行結果!!

[](https://3.bp.blogspot.com/-osb6w9vTl8o/Wl7D2hzXn2I/AAAAAAAAITc/KpzyaZf08Fseqa10QxbEEaIdKAJDELv6gCLcBGAs/s1600/%25E6%259C%25AA%25E5%2591%25BD%25E5%2590%258D.png)

希望對大家有幫助~