For Visual Studio. Create a migration. After you've defined your initial model, it's time to create the database. To add an initial migration, run the following command. Add-Migration InitialCreate dotnet ef migrations add InitialCreate Three files are added to your project under the Migrations directory: 0000_InitialCreate.cs. EF Core migrations are a set of commands which you can execute in NuGet Package Manager Console or in dotnet Command Line Interface (CLI). Open the Package Manager Console from the menu Tools -> NuGet Package Manager -> Package Manager Console in Visual Studio and execute.
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: 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.' Veteran presenter Ben Day maintains his own, 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. 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 at 10:20 AM.
Recently I’ve been playing around with Entity Framework Core and it’s been a great positive experience overall, however as I started to port one of my projects over I fell foul of the lack of Seeding support. For those that haven’t used the Seed functionality in EF 6, it’s basically a method to populate the database with data that is invoked when migrations finish. There is a open regarding seeding support in EF Core. My requirements are simple I’d like to use the dotnet CLI to run environment specific Migrations and Seeding from my continuous deployment pipeline.
In this post I’m going to show you how I got environment specific Migrations and Seeding working. There are a couple of things that work differently that we need to workaround but that’s fine. The first problem to solve is the, this is easily solved and not an issue at all. You can use a empty migration and seed the data in the migration, this is a great because the seed is ran once if I need to update the data I create a new migration.
We also benefit from being able to roll back any seed migrations. The second problem I came across is that. No problem I created a console app and problem solved. The third problem to solve is how to get the environment switch from ef database update. This is what took a little bit of work – it turns out that currently EF Core tools are geared around a ASP.NET project hence not supporting targeting class library projects, running migrations on web start isn’t something I wanted to do for my production apps.
Reviewing the EF Core (which is one of the benefits of open source) confirmed that EF tools are looking for a Startup class and the switch is set via the injected IHostingEnvironment. My first attempt was to pull the EnvironmentName directly from the environment variable turns out this won’t work as it is only set for the current cmd session. It was feeling like I was hitting friction so I changed direction and tried using WebHostBuilder instead, and bingo it worked, it turns out that you can have a Startup class and call Build but you don’t have to call Run so you don’t end up running Kestrel by mistake.
Below is a gist of the working solution with some commentary: Here I’m just bootstrapping our Startup class but notice I’m not calling Run. In the Startup ctor I take IHostingEnvironment and set it to a private variable, then when ConfigureServices is called I set a Environment Variable for future use. Note that if “Development” is passed as the environment we default to “local”, this is because “Development” is the default and I wanted to avoid using the default in CD. DbContext changes are quite simple if a database connectionstring is passed via OnConfiguring then we return.
Otherwise if no connectionstring is passed we set up the config using the environment variable we set in startup, it’s this code that will be called during a migration. Here is an example migration notice that DalSoftDbContext parameterless ctor is called allowing OnConfiguring (as described above) to use the environment config that was set using the environment variable.
Here is my project.json for reference but nothing special going on here. Now all my migrations using the dotnet CLI use the correct appsettings for example for appsettings.production.json: dotnet ef -project./DalSoft.Data -startup-project./DalSoft.Data database update -environment production.