Fermat.Domain.Exceptions 0.0.1

Fermat.Domain.Exceptions

Fermat.Exceptions is a library that provides a comprehensive exception handling system for .NET applications. It includes predefined exception types and interfaces for standardized error handling across your application.

Features

• Predefined exception types for common scenarios
• Standardized exception interfaces
• HTTP status code mapping
• Validation error handling
• Business rule violation handling
• Entity not found handling
• User-friendly error messages
• Correlation ID support

Installation

   dotnet add package Fermat.Domain.Exceptions

Content

Exception Types

Base Exception

• AppException: Base exception class with common properties and behaviors
  • Error code
  • Error details
  • Timestamp
  • Correlation ID

Domain Exceptions

• AppEntityNotFoundException: Thrown when an entity is not found

  • Entity type
  • Entity ID
  • Search criteria
  • Custom message

• AppBusinessException: Thrown when business rules are violated

  • Business rule code
  • Business rule message
  • Additional context

• AppValidationException: Thrown when validation fails

  • Validation errors collection
  • Field-specific errors
  • Custom validation messages

• AppAuthorizationException: Thrown when authorization fails

  • Required permissions
  • Access denied reason
  • User context

• AppUserFriendlyException: Thrown for user-friendly error messages

  • User-friendly message
  • Technical details (optional)
  • Suggested actions

Exception Interfaces

Core Interfaces

• IHasErrorCode: Interface for exceptions with error codes
• IHasErrorDetails: Interface for exceptions with detailed error information
• IHasTimestamp: Interface for exceptions with timestamp information
• IHasCorrelationId: Interface for exceptions with correlation ID tracking
• IHasStatusCode: Interface for exceptions with HTTP status codes
• IHasValidationErrors: Interface for exceptions with validation errors

Usage

Basic Exception Usage

// Entity not found
throw new AppEntityNotFoundException(typeof(User), userId);

// Business rule violation
throw new AppBusinessException("USER_INACTIVE", "User account is inactive");

// Authorization error
throw new AppAuthorizationException("ADMIN_REQUIRED", "Admin access required");

// User-friendly error
throw new AppUserFriendlyException(
    "Unable to process your request at this time",
    "Please try again later or contact support"
);

AppException Methods

AppException provides a fluent API for configuring exception properties:

// Basic usage
throw new AppBusinessException("User account is inactive")
    .WithCode("USER:INACTIVE:1001")
    .WithDetails("Account was deactivated by admin")
    .WithStatusCode(400)
    .WithCorrelationId("corr-123")
    .WithData("UserId", userId)
    .AppendData(new Dictionary<string, object>
    {
        { "LastLoginDate", lastLoginDate },
        { "DeactivationReason", reason }
    });

Available Methods

• WithData(string name, object value): Adds a single key-value pair to exception data
• AppendData(IDictionary<string, object> data): Adds multiple key-value pairs to exception data
• WithCode(string code): Sets the error code
• WithDetails(string details): Sets the error details
• WithStatusCode(int statusCode): Sets the HTTP status code
• WithCorrelationId(string correlationId): Sets the correlation ID

Features

• Standardized exception handling
• HTTP status code mapping
• Validation error collection
• Business rule violation handling
• Entity not found handling
• User-friendly messages
• Correlation tracking