Looking for a good technique for storing email templates

Question

Hello,

I am building a site in which we are making moderate use of email templates. As in, HTML templates which we pass tokens into like {UserName}, {Email}, {NameFirst}, etc.

I am struggling with where to store these, as far as best practice goes. I'll first show the approach I took, and I'd be really excited to hear some expert perspective as a far as alternate approaches.

I created HTML templates in a folder called /Templates/.

I call a static method in my service layer, which takes in the following arguments:

1. UserName
2. UserID
3. Email
4. TemplatePath ("~/Templates")
5. Email Subject

Within the service layer I have my static method SendUserEmail() which makes use of a Template class - which takes a path, loads it as a string, and has a AddToken() Method.

Within my static SendUserEmail(), I build the token list off of the method signature, and send the email.

This makes for a quite long method call in my actual usage, especially since I am calling from the web.config the "TemplatePath", and "Email Subject". I could create a utility that has a shorter method call than the ConfigurationManager.AppSettings, but my concern is more that I don't usually see method signatures this long and I feel like it's because I'm doing something wrong.

This technique works great for the emails I have now, which at the most are using the first 3 tokens. However in the future I will have more tokens to pass in, and I'm just wondering what approach to take.

Do I create methods specific to the email needing to be sent? ie. SendNewUserRegistration(), SendMarketingMaterial(), and each has a different signature for the parameters?

I am using ASP.NET Membership, which contains probably the extend of all the fields I'll ever need. There are three main objects, aspnet_User, aspnet_Mebership and aspnet_profile. If it was all contained in one object, I would have just passed that in. Is there performance concerns with passing in all 3, to get all the fields I need? That is versus just passing in aspnet_User.UserID, aspnet_User.Email, etc?

I could see passing in a dictionary with the token entries, but I'm just wondering if that is too much to ask the calling page?

Is there a way to stick these in a config file of it's own called Templates.config, which has tags like -

<Templates>
<EmailTemplate Name="New User Registration">
<Tokens>
<UserName>
<UserID>
<Email>
</Tokens>
<Message Subject="Hi welcome...">
   Hi {UserName}...
</Message>
</EmailTemplate>
</Templates>

I guess the main reason I'm asking, is because I'm having a hard time determining where the responsibility should be as far as determining what template to use, and how to pass in parameters. Is it OK if the calling page has to build the dictionary of TokenName, TokenValue? Or should the method take each in as a defined parameter? This looks out of place in the web.config, because I have 2 entries for and , and it feels like it should look more nested.

Thank you. Any techniques or suggestions of an objective approach I can use to ask whether my approach is OK.

Answer 1

First of all I would like to suggest you to use NVelocity as a template engine. As for main problem I think you can create an abstract class MailMessage and derive each one for every needed message (with unique template). So you will use this like following:

MailMessage message = new UserRegistrationMessage(tokens);
//some code that sends this message

Going this way you force each concrete XXXMessage class to be responsible for storing a template and filling it with the given tokens. How to deal with tokens? The simpliest way is to create a dictionary before passing it to the message, so each concrete message class will know how to deal with passed dictionary and what tokens it should contain, but you also need to remember what tokens it should contain. Another way (I like it more) is to create a general abstract type TokenSet and a derived one for every needed unique set of tokens. For example you can create a UserMessageTokenSet : TokenSet and several properties in it:

UserNameToken
SomeUserProfileDataToken

etc. So using this way you will always know, what data you should set for each token set and
UserRegistrationMessage will know what to take from this tokenSet.

There are a lot of ways to go. If you will describe you task better I think I will try suggest you something more concrete. But general idea is listed above. Hope it helps =)