@bardev provides a good solution, but unfortunately it's not ideal in all cases. Mine was one of them.
I'm using WebForms in a Website (I swear I'll never use a Website again--what a PITA) in VS 2013.
I tried the Razor suggestion, but mine being a Website I didn't get the all-important IntelliSense that the IDE delivers in an MVC project. I also like to use the designer for my templates--a perfect spot for a UserControl.
Nix on Razor again.
So I came up with this little framework instead (hat tips to @mun for UserControl and @imatoria for Strong Typing). Just about the only potential trouble spot I can see is that you have to be careful to keep your .ASCX filename in sync with its class name. If you stray, you'll get a runtime error.
FWIW: In my testing at least the RenderControl() call doesn't like a Page control, so I went with UserControl.
I'm pretty sure I've included everything here; let me know if I left something out.
HTH
Usage:
Partial Class Purchase
Inherits UserControl
Private Sub SendReceipt()
Dim oTemplate As MailTemplates.PurchaseReceipt
oTemplate = MailTemplates.Templates.PurchaseReceipt(Me)
oTemplate.Name = "James Bond"
oTemplate.OrderTotal = 3500000
oTemplate.OrderDescription = "Q-Stuff"
oTemplate.InjectCss("PurchaseReceipt")
Utils.SendMail("{0} <james.bond@mi6.co.uk>".ToFormat(oTemplate.Name), "Purchase Receipt", oTemplate.ToHtml)
End Sub
End Class
Base Class:
Namespace MailTemplates
Public MustInherit Class BaseTemplate
Inherits UserControl
Public Shared Function GetTemplate(Caller As TemplateControl, Template As Type) As BaseTemplate
Return Caller.LoadControl("~/MailTemplates/{0}.ascx".ToFormat(Template.Name))
End Function
Public Sub InjectCss(FileName As String)
If Me.Styler IsNot Nothing Then
Me.Styler.Controls.Add(New Controls.Styler(FileName))
End If
End Sub
Private ReadOnly Property Styler As PlaceHolder
Get
If _Styler Is Nothing Then
_Styler = Me.FindNestedControl(GetType(PlaceHolder))
End If
Return _Styler
End Get
End Property
Private _Styler As PlaceHolder
End Class
End Namespace
"Factory" Class:
Namespace MailTemplates
Public Class Templates
Public Shared ReadOnly Property PurchaseReceipt(Caller As TemplateControl) As PurchaseReceipt
Get
Return BaseTemplate.GetTemplate(Caller, GetType(PurchaseReceipt))
End Get
End Property
End Class
End Namespace
Template Class:
Namespace MailTemplates
Public MustInherit Class PurchaseReceipt
Inherits BaseTemplate
Public MustOverride WriteOnly Property Name As String
Public MustOverride WriteOnly Property OrderTotal As Decimal
Public MustOverride WriteOnly Property OrderDescription As String
End Class
End Namespace
ASCX Header:
<%@ Control Language="VB" ClassName="_Header" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional //EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!--
See https://www.campaignmonitor.com/blog/post/3317/ for discussion of DocType in HTML Email
-->
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<asp:PlaceHolder ID="plcStyler" runat="server"></asp:PlaceHolder>
</head>
<body>
ASCX Footer:
<%@ Control Language="VB" ClassName="_Footer" %>
</body>
</html>
ASCX Template:
<%@ Control Language="VB" AutoEventWireup="false" CodeFile="PurchaseReceipt.ascx.vb" Inherits="PurchaseReceipt" %>
<%@ Register Src="_Header.ascx" TagName="Header" TagPrefix="uc" %>
<%@ Register Src="_Footer.ascx" TagName="Footer" TagPrefix="uc" %>
<uc:Header ID="ctlHeader" runat="server" />
<p>Name: <asp:Label ID="lblName" runat="server"></asp:Label></p>
<p>Order Total: <asp:Label ID="lblOrderTotal" runat="server"></asp:Label></p>
<p>Order Description: <asp:Label ID="lblOrderDescription" runat="server"></asp:Label></p>
<uc:Footer ID="ctlFooter" runat="server" />
ASCX Template CodeFile:
Partial Class PurchaseReceipt
Inherits MailTemplates.PurchaseReceipt
Public Overrides WriteOnly Property Name As String
Set(Value As String)
lblName.Text = Value
End Set
End Property
Public Overrides WriteOnly Property OrderTotal As Decimal
Set(Value As Boolean)
lblOrderTotal.Text = Value
End Set
End Property
Public Overrides WriteOnly Property OrderDescription As Decimal
Set(Value As Boolean)
lblOrderDescription.Text = Value
End Set
End Property
End Class
Helpers:
'
' FindNestedControl helpers based on tip by @andleer
' at http://stackoverflow.com/questions/619449/
'
Public Module Helpers
<Extension>
Public Function AllControls(Control As Control) As List(Of Control)
Return Control.Controls.Flatten
End Function
<Extension>
Public Function FindNestedControl(Control As Control, Id As String) As Control
Return Control.Controls.Flatten(Function(C) C.ID = Id).SingleOrDefault
End Function
<Extension>
Public Function FindNestedControl(Control As Control, Type As Type) As Control
Return Control.Controls.Flatten(Function(C) C.GetType = Type).SingleOrDefault
End Function
<Extension>
Public Function Flatten(Controls As ControlCollection) As List(Of Control)
Flatten = New List(Of Control)
Controls.Traverse(Sub(Control) Flatten.Add(Control))
End Function
<Extension>
Public Function Flatten(Controls As ControlCollection, Predicate As Func(Of Control, Boolean)) As List(Of Control)
Flatten = New List(Of Control)
Controls.Traverse(Sub(Control)
If Predicate(Control) Then
Flatten.Add(Control)
End If
End Sub)
End Function
<Extension>
Public Sub Traverse(Controls As ControlCollection, Action As Action(Of Control))
Controls.Cast(Of Control).ToList.ForEach(Sub(Control As Control)
Action(Control)
If Control.HasControls Then
Control.Controls.Traverse(Action)
End If
End Sub)
End Sub
<Extension()>
Public Function ToFormat(Template As String, ParamArray Values As Object()) As String
Return String.Format(Template, Values)
End Function
<Extension()>
Public Function ToHtml(Control As Control) As String
Dim oSb As StringBuilder
oSb = New StringBuilder
Using oSw As New StringWriter(oSb)
Using oTw As New HtmlTextWriter(oSw)
Control.RenderControl(oTw)
Return oSb.ToString
End Using
End Using
End Function
End Module
Namespace Controls
Public Class Styler
Inherits LiteralControl
Public Sub New(FileName As String)
Dim _
sFileName,
sFilePath As String
sFileName = Path.GetFileNameWithoutExtension(FileName)
sFilePath = HttpContext.Current.Server.MapPath("~/Styles/{0}.css".ToFormat(sFileName))
If File.Exists(sFilePath) Then
Me.Text = "{0}<style type=""text/css"">{0}{1}</style>{0}".ToFormat(vbCrLf, File.ReadAllText(sFilePath))
Else
Me.Text = String.Empty
End If
End Sub
End Class
End Namespace
Public Class Utils
Public Shared Sub SendMail(Recipient As MailAddress, Subject As String, HtmlBody As String)
Using oMessage As New MailMessage
oMessage.To.Add(Recipient)
oMessage.IsBodyHtml = True
oMessage.Subject = Subject.Trim
oMessage.Body = HtmlBody.Trim
Using oClient As New SmtpClient
oClient.Send(oMessage)
End Using
End Using
End Sub
End Class
