Keep Up with Entity Framework Core Migrations: 3 EF Core Tutorials Worth Bookmarking

As you develop new apps, your data model changes by necessity. Entity Framework Core migrations—or EF Core migrations as the cool kids call them—help you keep your data model in sync with the database. It helps your apps run smoothly as they evolve and as you develop new apps that might draw upon the same database. Here are a few tutorials we found that can help ease the process:

Migrations—EF Core with ASP.NET Core MVC Tutorial

You'd expect our buddies at Microsoft to present some compelling tutorials on complex and semi-complex technical topics like this. And indeed they do. This tutorial—fourth in a series of 10—takes us through using EF core migrations to manage data model changes.

They open with,

"When you develop a new application, your data model changes frequently, and each time the model changes, it gets out of sync with the database. You started these tutorials by configuring the Entity Framework to create the database if it doesn't exist. Then each time you change the data model—add, remove, or change entity classes or change your DbContext class—you can delete the database and EF creates a new one that matches the model and seeds it with test data.

This method of keeping the database in sync with the data model works well until you deploy the application to production. When the application is running in production, it is usually storing data that you want to keep, and you don't want to lose everything each time you make a change such as adding a new column. The EF Core Migrations feature solves this problem by enabling EF to update the database schema instead of creating a new database."

Walkthrough: Entity Framework Core 1.1 with Migrations

Veteran Visual Studio Live! presenter Ben Day maintains his own blog, on which he has some excellent step-by-step tutorials and walkthroughs. To help ease some of the confusion around EF migrations, he has—as you would expect—a perfectly well-organized and easy to understand walkthrough, complete with section headers to break up the sections, screen shots, and code samples.

It's a nice straightforward entry. "Here's a walk-through on how to create a new solution that uses an ASP.NET Core project, an MSTest unit test project, and Entity Framework Core 1.1 (EFCore1.1). I'm not sure if you’ve found this to be the case but I've been struggling with the documentation for a few days trying to figure out how to get EF Core Migrations working with the "dotnet ef" command line. This sample will show you how to do all of this with the current version of the .NET Core SDK. For this walk-through I'm going to use the solution name of "Benday.EfCore." We'll start by using my "create" script from that blog post."

Ben's walkthrough also lets you simply go directly to the code if you'd like. He provides a link to do so before he gets into his walkthrough.

Entity Framework Core Migrations

This is another thoughtfully and cleanly organized tutorial. It breaks up each section with section headers (as represented in the mini table of contents), and show code samples in tinted boxes along the way. This tutorial begins with a roadmap of what you'll be learning.
"The following topics are covered in this document:
  • Creating a Migration
  • Removing a Migration
  • Applying a Migration
  • Reversing a Migration
  • Applying a Migration to a Remote Database
  • Executing Custom SQL
  • Targeting Multiple Providers

When developing applications, the model is likely to change often as new requirements come to light. The database needs to be kept in sync with the model. The migrations feature enables you to make changes to your model and then propagate those changes to your database schema. Migrations are enabled by default in EF Core. They are managed by executing commands. If you have Visual Studio, you can use the Package Manager Console (PMC) to manage migrations. Alternatively, you can use a command line tool to execute Entity Framework CLI commands to create a migration."

Posted by Lafe Low on 12/21/2017

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