.net - How to change exception message of Exception object?

Question

How can i change the Message of an Exception object in C#?

Bonus Chatter

The Message property of Exception is read-only:

public virtual string Message { get; } 

Additional Reading

The same question, in PHP, was answered, "You can't", but gave a workaround:

You can however determine it's class name and code, and throw a new one, of the same class, with same code, but with different message.

How can i determine an exception's class name, and throw a new one of the same class, but with a different message, in C#?

e.g.:

catch (Exception e) {    Exception e2 = Activator.CreateInstance(e.GetType());    throw e2; } 

doesn't work because the Message property of an exception is read-only and .NET. See original question.

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Update

i tried catching each type of exception i expect:

try {     reader.Read(); } catch (OleDbException e) {    throw new OleDbException(e, sql); } catch (SqlException e) {    throw new SqlException (e, sql); } catch (IBM.DbException e) {    throw new IBM.DbException(e, sql); } catch (OdbcException e) {    throw new OdbcException (e, sql); } catch (OracleException e) {    throw new OracleException (e, sql); } 

Except that now my code forces a dependency on assemblies that won't be present in every solution.

Also, now the exception seems to come from my code, rather than the line that threw it; i lose the exception's location information

Answer 1

You create a new Exception (or – better – specific subtype) that has the new message (and pass the original exception as InnerException).

Eg.

throw new MyExceptionType("Some interesting message", originalException); 

NB. If you really want to use Activator.CreateInstance you can use an overload that can be passed parameters, but different Exception derived types cannot be relied on to have an constructor overload for (message, innerException).

Answer 2

i found the solution in a blog post linked from a news site:

catch (Exception e) {    Exception e2 = (Exception)Activator.CreateInstance(e.GetType(), message, e);    throw e2; } 

It's not perfect (you lose your stack trace); but that's the nature of .NET.