DainnCommon 9.0.2

DainnCommon

A shared library containing common functionality used across Dainn projects.

Overview

This library provides shared infrastructure components that are used by multiple Dainn projects, including:

• Exception handling classes
• Middleware components
• Database provider configuration helpers
• Entity Framework Core extensions

Components

Exceptions

Common exception classes for consistent error handling:

• BusinessRuleException - Thrown when business rules are violated
• NotFoundException - Thrown when requested resources are not found
• ValidationException - Thrown when input validation fails

Middleware

• ExceptionMiddleware - Global exception handling middleware that formats exceptions into consistent JSON responses

Extensions

• DbContextProviderExtensions - Extension methods for configuring database providers (SQLite, SQL Server, PostgreSQL, MySQL, InMemory)
• PostgreSQL UUID configuration helpers

Data

• DbContextFactoryHelper - Helper methods for creating DbContext instances at design time

Logging

• DailyFileLogger - Thread-safe file logger that creates separate log files for each day
• IDailyFileLogger - Interface for daily file logging
• DailyFileLoggerOptions - Configuration options for daily file logging
• Log files are automatically organized by date (e.g., app-2025-12-25.log)
• Automatic log file rotation and cleanup based on retention policy

Usage

Adding to Your Project

Add a project reference to DainnCommon:

<ProjectReference Include="..\DainnCommon\DainnCommon.csproj" />

Using Exceptions

using DainnCommon.Exceptions;

throw new NotFoundException("User", userId);
throw new BusinessRuleException("Cannot delete active user");
throw new ValidationException(validationErrors);

Using Exception Middleware

using DainnCommon.Middleware;

app.UseMiddleware<ExceptionMiddleware>();

Configuring Database Providers

using DainnCommon.Extensions;

services.AddDbContext<MyDbContext>(options =>
{
    options.ConfigureDatabaseProvider(provider, connectionString);
});

Configuring PostgreSQL UUIDs

using DainnCommon.Extensions;

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    if (Database.IsNpgsql())
    {
        modelBuilder.ConfigurePostgreSqlUuids(setDefaultValue: true);
    }
}

Using DbContext Factory Helper

using DainnCommon.Data;

public class MyDbContextFactory : IDesignTimeDbContextFactory<MyDbContext>
{
    public MyDbContext CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<MyDbContext>();
        var configuration = DbContextFactoryHelper.BuildConfiguration();
        var (provider, connectionString) = DbContextFactoryHelper.GetDatabaseConfiguration(configuration);
        DbContextFactoryHelper.ConfigureDbContext(optionsBuilder, provider, connectionString);
        return new MyDbContext(optionsBuilder.Options);
    }
}

Using Daily File Logger

Configuration in appsettings.json

{
  "DailyFileLogging": {
    "LogDirectory": "logs",
    "LogFilePrefix": "app",
    "MinimumLogLevel": "Information",
    "IncludeTimestamp": true,
    "TimestampFormat": "yyyy-MM-dd HH:mm:ss.fff",
    "IncludeLogLevel": true,
    "RetentionDays": 30,
    "CreateDirectoryIfNotExists": true
  }
}

Registering the Logger

using DainnCommon.Extensions;

// With configuration
builder.Services.AddDailyFileLogging(builder.Configuration);

// Or with explicit options
builder.Services.AddDailyFileLogging(options =>
{
    options.LogDirectory = "logs";
    options.LogFilePrefix = "myapp";
    options.MinimumLogLevel = LogLevel.Information;
    options.RetentionDays = 30;
});

Using the Logger

using DainnCommon.Logging;

public class MyService
{
    private readonly IDailyFileLogger _logger;

    public MyService(IDailyFileLogger logger)
    {
        _logger = logger;
    }

    public void DoSomething()
    {
        _logger.LogInformation("Operation started");
        
        try
        {
            // Your code here
            _logger.LogInformation("Operation completed successfully");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Operation failed");
        }
    }
}

Log File Format

Log files are created with the format: {LogFilePrefix}-{yyyy-MM-dd}.log

Example: app-2025-12-25.log

Each log entry includes:

• Timestamp (if enabled)
• Log level (if enabled)
• Message
• Exception details (if provided)

Supported Database Providers

• SQLite
• SQL Server
• PostgreSQL / Npgsql
• MySQL / MariaDB
• InMemory

Requirements

• .NET 8.0 or later
• Entity Framework Core 8.0.11 or later