DataAccess

Repository and Unit Of Work implementation over a relational database.

Overview

This library provides an abstraction and implementation of data access to a relational database. It targets two main goals:

• support for consistent development model for reading or modifying data in the entire application
• enforce good separation of concerns by separating data access from business logic

The implementation is done with Entity Framework, but the client code should not have any direct dependencies (reference assemblies) to it. The client code depends only on the abstract interface provided by the library and does not know details about the underlying ORM.

Usage Patterns

IRepository is a generic interface for querying data for read-only purposes:

private readonly IRepository rep; // injected w/ Dependency Injection
public IEnumerable<Order> GetAllLargeOrders(int amount)
{
	var orders = rep.GetEntities<Order>()
					.Where(o => o.OrderLines.Any(ol => ol.Amount > amount)
	return orders.ToList();
}

Queries may be returned to be composed and executed by caller code:

private readonly IRepository rep; // injected w/ Dependency Injection
private IQueriable<Order> GetAllLargeOrders(int amount)
{
	var orders = rep.GetEntities<Order>()
					.Where(o => o.OrderLines.Any(ol => ol.Amount > amount)
	return orders;
}

public IEnumerable<OrderSummary> GetRecentLargeOrders(int amount)
{
   int thisYear = DateTime.UtcNow.Year;
   var orders = GetAllLargeOrders(amount)
				   .Where(o.Year == thisYear)
				   .Select(o => new OrderSummary
				                {
				                ...
				                });
	return orders;
}

IUnitOfWork is a generic interface for creating a well defined scope for adding, modifying or deleting data:

public void ReviewLargeAmountOrders(int amount, ReviewData data)
{
	using (IUnitOfWork uof = rep.CreateUnitOfWork())
	{
		IQueryable<Order> orders = uof.GetEntities<Order>()
					.Where(o => o.OrderLines.Any(ol => ol.Ammount > amount);
		foreach(var order in orders)
		{
			order.Status = Status.Reviewed;
			order.Cutomer.Name = data.CustomerNameUpdate;
			...
		}
		
		ReviewEvent re = new ReviewEvent {...}
		uof.Add(re)
		
		uof.SaveCanges();
	}
}

Getting Started

Create a data model project which contains the POCOs that are mapped to the database model. This will also contain the Entity Framework DbContext.

Register into your Dependency Injection container the following mappings:

Contract	Implementation
IDbContextFactory	DbContextFactory<MyEntities>
IRepository	Repository
IInterceptorsResolver	InterceptorsResolver

Related Repository

iQuarc.AppBoot