OK, I admit it. I've caught the CRM development bug. What started as a harmless bit of fun working on document library integration between CRM & SharePoint has now developed into an obsession. In this post I will describe how to build a plug-in that examines the body of any e-mail promoted promoted from Outlook or the e-mail router and converts the HTML into plain text.
After a bit of searching, I found a good article which showed how you could use regular expressions to remove unwanted HTML tags leaving just the plain text - Convert HTML to Plain Text. Converting this from C# to VB (my preferred choice of language) and stripping out some of the bits I didn't need, I came up with the following code which forms the basis of this plug-in.
Private Function ConvertHTMLToText(ByVal Source As String) As String
Dim result As String = Source
' Remove formatting that will prevent regex from running reliably ' \r - Matches a carriage return \u000D. ' \n - Matches a line feed \u000A. ' \f - Matches a form feed \u000C. ' For more details see http://msdn.microsoft.com/en-us/library/4edbef7e.aspxresult = Replace(result, "[\r\n\f]", String.Empty, Text.RegularExpressions.RegexOptions.IgnoreCase)
' replace the most commonly used special characters:result = Replace(result, "<", "<", RegexOptions.IgnoreCase)
result = Replace(result, ">", ">", RegexOptions.IgnoreCase)
result = Replace(result, " ", " ", RegexOptions.IgnoreCase)
result = Replace(result, """, """", RegexOptions.IgnoreCase)
result = Replace(result, "&", "&", RegexOptions.IgnoreCase)
' Remove ASCII character code sequences such as &#nn; and &#nnn;result = Replace(result, "&#[0-9]{2,3};", String.Empty, RegexOptions.IgnoreCase)
' Remove all other special characters. More can be added - see the following for more details: ' http://www.degraeve.com/reference/specialcharacters.php ' http://www.web-source.net/symbols.htmresult = Replace(result, "&.{2,6};", String.Empty, RegexOptions.IgnoreCase)
' Remove all attributes and whitespace from the <head> tagresult = Replace(result, "< *head[^>]*>", "<head>", RegexOptions.IgnoreCase)
' Remove all whitespace from the </head> tagresult = Replace(result, "< */ *head *>", "</head>", RegexOptions.IgnoreCase)
' Delete everything between the <head> and </head> tagsresult = Replace(result, "<head>.*</head>", String.Empty, RegexOptions.IgnoreCase)
' Remove all attributes and whitespace from all <script> tagsresult = Replace(result, "< *script[^>]*>", "<script>", RegexOptions.IgnoreCase)
' Remove all whitespace from all </script> tagsresult = Replace(result, "< */ *script *>", "</script>", RegexOptions.IgnoreCase)
' Delete everything between all <script> and </script> tagsresult = Replace(result, "<script>.*</script>", String.Empty, RegexOptions.IgnoreCase)
' Remove all attributes and whitespace from all <style> tagsresult = Replace(result, "< *style[^>]*>", "<style>", RegexOptions.IgnoreCase)
' Remove all whitespace from all </style> tagsresult = Replace(result, "< */ *style *>", "</style>", RegexOptions.IgnoreCase)
' Delete everything between all <style> and </style> tagsresult = Replace(result, "<style>.*</style>", String.Empty, RegexOptions.IgnoreCase)
' Insert tabs in place of <td> tags result = Replace(result, "< *td[^>]*>", vbTab, RegexOptions.IgnoreCase) ' Insert single line breaks in place of <br> and <li> tags result = Replace(result, "< *br[^>]*>", vbCrLf, RegexOptions.IgnoreCase) result = Replace(result, "< *li[^>]*>", vbCrLf, RegexOptions.IgnoreCase) ' Insert double line breaks in place of <p>, <div> and <tr> tags result = Replace(result, "< *div[^>]*>", vbCrLf + vbCrLf, RegexOptions.IgnoreCase) result = Replace(result, "< *tr[^>]*>", vbCrLf + vbCrLf, RegexOptions.IgnoreCase) result = Replace(result, "< *p[^>]*>", vbCrLf + vbCrLf, RegexOptions.IgnoreCase) ' Remove all reminaing html tagsresult = Replace(result, "<[^>]*>", String.Empty, RegexOptions.IgnoreCase)
' Replace repeating spaces with a single spaceresult = Replace(result, " +", " ")
' Remove any trailing spaces and tabs from the end of each line result = Replace(result, "[ \t]+\r\n", vbCrLf) ' Remove any leading whitespace charactersresult = Replace(result, "^[\s]+", String.Empty)
' Remove any trailing whitespace charactersresult = Replace(result, "[\s]+$", String.Empty)
' Remove extra line breaks if there are more than two in a row result = Replace(result, "\r\n\r\n(\r\n)+", vbCrLf + vbCrLf) ' Thats it. Return resultEnd FunctionAll that remains is to implement the IPlugin.Execute method. In order to be able to modify the e-mail message before the e-mail activity gets created in the database, I had to figure out which event(s) to intercept. Through a bit of trial and error, I observed that any e-mail promoted from Outlook triggers the "DeliverPromote" event, whereas any incoming e-mail handled by the e-mail router triggers the "DeliverIncoming" event. Interestingly enough, the "Create" event was also called as a child pipeline for these events, but modifying the message here didn't have any effect, even in the pre-processing stage.
Because plug-ins have the potential to introduce significant performance and scalability issues into your environment, it is important to ensure that the code is as efficient as possible. To that end I added additional checks to ensure that the even if registered on multiple events, the main code will only run if the plug-in:
- is running on the 'DeliverPromote' or 'DeliverIncoming' messages
- is running synchronously
- is running against the 'Email' entity
- is running in the 'pre-processing' stage of the pipeline
- is running in a 'Parent' pipeline
Public Class ConvertHtmlToText
Implements IPluginPublic Sub Execute(ByVal context As IPluginExecutionContext) Implements IPlugin.Execute
' Exit if any of the following conditions are true: ' 1. plug-in is not running synchronously ' 2. plug-in is not running against the 'Email' entity ' 3. plug-in is not running in the 'pre-processing' stage of the pipeline ' 4. plug-in is not running in a 'Parent' pipelineIf Not (context.Mode = 0) Or Not (context.PrimaryEntityName = "email") Or Not (context.Stage = 10) Or Not (context.InvocationSource = 0) Then
Exit Sub
End If
If (context.MessageName = "DeliverPromote") Or (context.MessageName = "DeliverIncoming") Then
For Each item In context.InputParameters.Properties
If (item.Name = "Body") Then
context.InputParameters.Properties.Item("Body") = ConvertHTMLToText(CStr(item.Value))
End If
NextEnd If
End Sub
End ClassAs always, I have include the source code to my project here. Please do bear in mind that I haven't included any error handling or logging, so it's not production-ready. However, it should provide you with a good head-start.
This posting is provided "AS IS" with no warranties, and confers no rights.
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