# AutoMapper.Collection.EntityFrameworkCore `Automapper.Collection.EntityFrameworkCore` will help you when mapping an EntityFramework Core DbContext-object. [](https://www.nuget.org/packages/Automapper.Collection.EntityFrameworkCore/) ## Configuration examples - Usage together with Dependency injection and AutoMapper.Extensions.Microsoft.DependencyInjection package ``` var services = new ServiceCollection(); services .AddEntityFrameworkInMemoryDatabase() .AddDbContext(); services.AddAutoMapper((serviceProvider, automapper) => { automapper.AddCollectionMappers(); automapper.UseEntityFrameworkCoreModel(serviceProvider); }, typeof(DB).Assembly); var serviceProvider = services.BuildServiceProvider(); ``` **Note:** User defined equality expressions will overwrite primary key expressions. What about comparing to a single existing Entity for updating? -------------------------------- Automapper.Collection.EntityFrameworkCore does that as well through extension method from of DbSet. Translate equality between dto and EF object to an expression of just the EF using the dto's values as constants. ``` dbContext.Orders.Persist(mapper).InsertOrUpdate(newOrderDto); dbContext.Orders.Persist(mapper).InsertOrUpdate(existingOrderDto); dbContext.Orders.Persist(mapper).Remove(deletedOrderDto); dbContext.SubmitChanges(); ``` **Note:** This is done by converting the OrderDTO to Expression> and using that to find matching type in the database. You can also map objects to expressions as well. Persist doesn't call submit changes automatically How to get it -------------------------------- Use NuGet Package Manager to install the package or use any of the following commands in NuGet Package Manager Console. ``` PM> Install-Package AutoMapper.Collection.EntityFrameworkCore ```