How to use the inner exception when writing custom exception in c#

Question

I am writing custom exception class and using them to log to elmah whenever required.

public class MyCustomLogException : Exception
{
    public string Property1 { get; protected set; }
    public string Property2 { get; protected set; }
    public string Property3 { get; protected set; }

    internal MyCustomLogException(string property1, string property2, string property3)
    {
        Property1 = property1;
        Property2 = property2;
        Property3 = property3;        
    }

    public override string Message
    {
        get
        {
            return string.Format("Error logging to db using Property1 = {0}, Property2 = {1} and Property3 = {2}", Property1, Property2, Property3);
        }
    }
}

and I am using

public int LogSomethingToDb(SomeModel log)
{
    try
    {
        // log to db
    }
    catch(Exception exception)
    {
        // to do how to use this exception ?
        throw new MyCustomLogException(log.Property1, log.Property2, log.Property3);
    }
}

How do I use the above exception message, stack trace etc so that I dont end up eating the 'exception' message.

I want the exact detail of the exception to also be logged for eg if its a entity framework exception or a null ref exception etc just by reading the elmah logs.

Update

Yea sure earlier with my code i was getting MyCustomLogException as the exception logged and message of "Error logging to db using Property1 = {0}, Property2 = {1} and Property3 = {2}" as the exception message. This way just by reading the log I can figure out what is wrong and then may be read the inner exception to get more details. – Yasser 8 mins ago

Now with the new code the actual exception class Sql in my case is getting logged and the exception message of "Violation of UNIQUE KEY constraint 'IX_abc_log'. Cannot insert duplicate key in object 'dbo.abc'. The statement has been terminated." is logged and my custom exception class and message are logged as inner exception

Answer 1

When you are writing custom exceptions, your custom exception should look like this as minimum:

[Serializable]
public class CustomException : Exception
{
    public CustomException()
        : base() { }

    public CustomException(string message)
        : base(message) { }

    public CustomException(string format, params object[] args)
        : base(string.Format(format, args)) { }

    public CustomException(string message, Exception innerException)
        : base(message, innerException) { }

    public CustomException(string format, Exception innerException, params object[] args)
        : base(string.Format(format, args), innerException) { }

    protected CustomException(SerializationInfo info, StreamingContext context)
        : base(info, context) { }
}

You'll see that now the Exception can take an inner exception in it's constructor and this is what you're looking for.

When you want to add your properties, you can add one more constructor which looks like:

    public CustomException(string message, Exception innerException, string property1, string property2)
        : base(message, innerException) { 
    // Do whatever you want with the extra properties here.    
}

EDIT The questionater, would like to see a custom exception message, therefore the CustomException is modified like:

[Serializable]
public class CustomException : Exception
{
    public CustomException()
        : base() { }

    public CustomException(string message)
        : base(message) { }

    public CustomException(string format, params object[] args)
        : base(string.Format(format, args)) { }

    public CustomException(string message, Exception innerException)
        : base(message, innerException) { }

    public CustomException(string format, Exception innerException, params object[] args)
        : base(string.Format(format, args), innerException) { }

    protected CustomException(SerializationInfo info, StreamingContext context)
        : base(info, context) { }

    // Added a custom constructor to allow adding the custom properties:
    internal CustomException(string message, Exception innerException, string property1, string property2, string property3) 
        : base(message, innerException) { }
    {
        Property1 = property1;
        Property2 = property2;
        Property3 = property3;        
    }

    // 3 properties holding all the values of the properties passed to it.
    public string Property1 { get; protected set; }
    public string Property2 { get; protected set; }
    public string Property3 { get; protected set; }

    // Override the message to allow custom exception message to be passed to Elmah.
    public override string Message
    {
        get
        {
            return string.Format("Error logging to db using Property1 = {0}, Property2 = {1} and     Property3 = {2}", Property1, Property2, Property3);
        }
    }
}