entity-framework.md

Entity Framework (EF)

O/RM in .NET Core

What is EF?

• Object-relational mapper (O/RM)
• Supports many different DB providers (list)
  examples:
  • MS SQL Server
  • SQLite
  • PostgreSQL
  • MySQL
  • In-Memory (for testing)
• Latest version: EF Core 3.0
• NuGet (example): Microsoft.EntityFrameworkCore.SqlServer

Getting Started

• Follow installing docs to add EF to project
  • Make sure to install global EF tools: dotnet tool install --global dotnet-ef
• Work through tutorials in EF docs
  • Tutorial for ASP.NET Core
• Tips:
  • Run local SQL Server using Docker:
    docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=yourStrong(!)Password' -e 'MSSQL_PID=Express' -p 1433:1433 -d mcr.microsoft.com/mssql/server
  • Install and use free SQL Server Developer Edition or SQL Server 2017 Express LocalDB
  • Use In-Memory DB for simple test scenarios

Building a Model

<!--#include file="entity-framework/0010-intro/Person.cs" -->

• Read more about creating a Model

Setting up the Context

<!--#include file="entity-framework/0010-intro/Context.cs" -->

Writing Data

<!--#include file="entity-framework/0010-intro/WriteToDB.cs" -->

• Read more about writing data

Writing Data to Related Sets

<!--#include file="entity-framework/0030-joins/AddingWithJoin.cs" -->

• Note single call to Add and SaveChangesAsync

Querying Data

<!--#include file="entity-framework/0010-intro/ReadFromDB.cs" -->

• Read more about querying data

Querying Data

<!--#include file="entity-framework/0030-joins/QueryWithJoin.cs" -->

• Include: Getting Order with related Customer

Learn by Example

• Address Book example on GitHub
• AddJsonOptions in Startup.cs for handling loops in JSON serialization
• services.AddDbContext in Startup.cs for adding EF context to ASP.NET Core Dependency Injection
• AutoMapper in Startup.cs
• Migrations
  • Read more about migrations...
• Visual Studio Scaffolding for controllers
• EF's Include in GroupsController.cs

EF Core + ASP.NET Core Cheat Sheet

Entity Framework Cheat Sheet

Further Readings and Exercises

• Readings
  • Entity Framework Documentation
  • EF Tutorial with ASP.NET Core
• Videos
  • Want to know more details? Watch Entity Framework Core on Channel 9
• Exercises
  • Cash Desk Quiz