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Revati S Misra

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Aryan Kumar

Aryan Kumar

12-Oct-2023

Creating custom exceptions in .NET Core allows you to define exception types that are specific to your application's needs. This is valuable for more precise error handling and conveying detailed information about exceptional situations. Here's how to create custom exceptions in .NET Core:

Define a Custom Exception Class: To create a custom exception, you need to define a new class that derives from the built-in Exception class or one of its derivatives, such as ApplicationException. Here's a basic example:

public class CustomException : Exception
{
    public CustomException()
    {
    }

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

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

Custom Properties and Constructors: You can add custom properties and constructors to your exception class to provide additional information about the exceptional situation. For example, you might include properties to indicate error codes, error categories, or specific context details.

public class CustomException : Exception
{
    public int ErrorCode { get; }

    public CustomException(int errorCode)
    {
        ErrorCode = errorCode;
    }

    // Other constructors...
}

Throwing Custom Exceptions: In your code, when you encounter a situation that warrants raising the custom exception, you can throw it using the throw keyword. You can also pass in additional information, such as the error message or context-specific details.

if (someConditionIsNotMet)
{
    throw new CustomException("The condition is not met.");
}

Handling Custom Exceptions: To handle custom exceptions, use try-catch blocks in your code as you would for built-in exceptions. Catch the custom exception type and handle it as needed. You can access the custom properties to gain insight into the exception.

try
{
    // Code that may throw CustomException
}
catch (CustomException ex)
{
    Console.WriteLine($"Custom Exception: {ex.Message}");
    Console.WriteLine($"Error Code: {ex.ErrorCode}");
}

Exception Inheritance Hierarchy: It's a good practice to define a clear inheritance hierarchy for your custom exceptions. You can create more specific custom exceptions that inherit from a base custom exception to represent different error scenarios. This allows you to handle exceptions at various levels of granularity.

public class SpecificException : CustomException
{
    public SpecificException() : base("A specific error occurred.")
    {
    }

    // Additional custom properties and constructors...
}

Documentation and Usage: Document your custom exceptions, including their purpose and usage, in your API documentation or code comments. This helps other developers understand the exceptions and how to handle them correctly.

By creating custom exceptions in .NET Core, you can add meaningful context to error situations in your application and improve error handling. Custom exceptions help you communicate specific error scenarios more clearly and enable you to respond to exceptional situations in a tailored and predictable way.

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