Question

I am using Dynamic Data and to apply Unique key and other database level validations i have overridden the SubmitChanges function.

This gives me original error, which i am able to show to the end user. But, this message is like this:

Violation of UNIQUE KEY constraint 'UK_CountryName_Country'. Cannot insert duplicate key in object 'dbo.Country'. The duplicate key value is (America).
The statement has been terminated.

I need the following keywords of the message:

1. UNIQUE KEY
2. UK_CountryName_Country
3. America

I have written following Regex:

System.Text.RegularExpressions.Regex.Split(e.Message.ToString(), "^Violation of (UNIQUE KEY){1} constraint '([a-zA-Z_]*)'. Cannot insert duplicate key in object 'dbo.([a-zA-Z]*)'. The duplicate key value is ")

I have succeeded in getting #1 & #2, but #3.

Can anyone help me. Also, is there any cleaner way to achieve it.
FYI: I would be catching other types of database errors as well.

Thanks

Answer 1

With your example expression, it seemed you were trying to match the Country from dbo.Country instead of America as you asked, so I included both in my expression/code:

 Dim ExpressionText As String = "^Violation of (?<KeyType>.*?) constraint '(?<ConstraintName>[^']*)'\.[^']*'(?<ObjectName>[^']*)'[^(]*\((?<KeyValue>[^)]*)\)"
 Dim SearchText As String = "Violation of UNIQUE KEY constraint 'UK_CountryName_Country'. Cannot insert duplicate key in object 'dbo.Country'. The duplicate key value is (America). " _
                               & vbCrLf & "The statement has been terminated."
 Dim regex As New System.Text.RegularExpressions.Regex(ExpressionText)
 Dim mc As System.Text.RegularExpressions.Match = regex.Match(SearchText)

 Response.Write(mc.Groups("KeyType").Value)           ' writes UNIQUE KEY
 Response.Write(mc.Groups(1).Value)                   ' writes UNIQUE KEY
 Response.Write(mc.Groups("ConstraintName").Value)    ' writes UK_CountryName_Country
 Response.Write(mc.Groups(2).Value)                   ' writes UK_CountryName_Country
 Response.Write(mc.Groups("ObjectName").Value)        ' writes dbo.Country
 Response.Write(mc.Groups(3).Value)                   ' writes dbo.Country
 Response.Write(mc.Groups("KeyValue").Value)          ' writes America
 Response.Write(mc.Groups(4).Value)                   ' writes America

The expression is designed to be very tolerant of the type of error message, as there are other types of Key Constraints that can be violated. I could not find a list of the possible errors, but here is a breakdown of the expression:

^Violation of                   # Match literal text
(?<KeyType>.*?) constraint      # Capture the words that come before  " constraint"
'(?<ConstraintName>[^']*)'\.    # Capture whatever is inside the single quotes:  '
[^']*                           # Match anything up to the next single quote
'(?<ObjectName>[^']*)'          # Capture whatever is inside the single quotes
[^(]*                           # Match anything up to the next open parentheses:  ( 
\((?<KeyValue>[^)]*)\)          #Capture whatever is inside the parentheses

You can get rid of the parts that look like ?<Something> if you do not want to use named capturing groups, and only want to use the numbers