In this tutorial, you start using the EF Core migrations feature for managing data model changes. In later tutorials, you'll add more migrations as you change the data model.
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's 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. These tutorials show how to use CLI commands. Information about the PMC is at the end of this tutorial. In the appsettings. This change sets up the project so that the first migration will create a new database. This isn't required to get started with migrations, but you'll see later why it's a good idea.
As an alternative to changing the database name, you can delete the database. Save your changes and build the project. Then open a command window and navigate to the project folder. Here's a quick way to do that:. If you see an error message No executable found matching command "dotnet-ef"see this blog post for help troubleshooting.
If you see an error message " cannot access the file When you executed the migrations add command, EF generated the code that will create the database from scratch. The Up method of the InitialCreate class creates the database tables that correspond to the data model entity sets, and the Down method deletes them, as shown in the following example. Migrations calls the Up method to implement the data model changes for a migration. When you enter a command to roll back the update, Migrations calls the Down method.
This code is for the initial migration that was created when you entered the migrations add InitialCreate command. The migration name parameter "InitialCreate" in the example is used for the file name and can be whatever you want. It's best to choose a word or phrase that summarizes what is being done in the migration.
I'd like to understand how to run the command and have it actually execute. I am learning how to use ASP. Net Core 1. It is a Microsoft tutorial that can be found here. The completed tutorial can be downloaded from git, as instructed. Performing these steps I open the download project and follow the steps in the readme. It states the following:.
After downloading the project, create the database by entering dotnet ef database update at a command-line prompt. Which I attempted. I used visual studio developer command prompt as admin and first change directory to the project root, where the appsettings.
I then typed in the following:. What is strange to me is that if I run the following command I get output, which indicates to me that dotnet. I have both the ASP.
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm using the latest 1. I have a migration to run on a quite big database. Timeout expired.
The timeout period elapsed prior to completion of the operation or the server is not responding. The error message you are getting is for a Command timeout, not a connection timeout.
As mentioned by Pace in comments, since EF Core 2. Create a separate class in your project that implements the IDesignTimeDbContextFactory interface and use the DbContextoptionsBuilder to configure the behaviour you want - in this case, setting the command timeout value to seconds:. Make sure that your existing DbContext has a constructor that takes a DbContextOptions object as a parameter:.
When the tooling runs the migration, it looks first for a class that implements IDesignTimeDbContextFactory and if found, will use that for configuring the context. Runtime behaviour is not affected. There is no way to set the CommandTimeout on a context when using EF commands. But you can set it globally in the constructor, and then remove it later if you don't need to keep it:. You can set the timeout for migration only by setting the timeout on the context before calling the Migrations method:.
Set timeout for migrations ef. CommandTimeout property. CommandTimeout Property. Note that I also use a different connection string during migrations - the user has higher permissions than the website and the connection timeout is longer.
See this question - How to use a different connection string but same database for migrations. Learn more. How to set Entity Framework Core migration timeout? Ask Question. Asked 3 years, 7 months ago. Active 1 year, 4 months ago. Viewed 17k times. How should I do this? Artiom 6, 2 2 gold badges 32 32 silver badges 43 43 bronze badges.
Andrzej Gis Andrzej Gis Active Oldest Votes. Create a separate class in your project that implements the IDesignTimeDbContextFactory interface and use the DbContextoptionsBuilder to configure the behaviour you want - in this case, setting the command timeout value to seconds: using Microsoft.I'm currently working on an inherited. NET Core project and I'm loving the experience.
I'm still using the project. NET Core projects. The project also makes use of the newest EF Core so it's all running on the edge of the. NET technology. EF Core Code First is great but the tooling is still rough around the edges. Some things are not there or some of them are not feature complete.Intro to EntityFrameworkCore: One-to-Many Relationships
So my problem in this instance was working with migrations against an existing database and model. In the old EF6x world, I could use this command:. This command creates a baseline, a starting point to allow us to apply further schema changes through migrations. Unfortunately, this is one of the EF Core features that's missing.
The -ignoreChanges parameter is not available. Below, I explain my workaround and hopefully this can help you as well if you are faced with the same problem. First, you need to add the tooling to the necessary projects. And there's a caveat here. In other words, EF Core tools can't run against a class library.
You need a. NET Core website. However, you still need to install the EF Core tools to your DB project if this lives outside your application project, which is common on larger projects.
EF Core migrations with existing database schema and data
Add the appropriate NuGet package under the "tools" section in the project. Next, on your website or console app ASP. NET [Core] you need to add the following NuGet packages in the "references" and "tools" sections respectively. Open the command line in order to use the. This will ensure that the migration will run against your database without altering your existing schema assuming there are no changes. You can leave the Down method as is.
Next, you want to run this migration against your database so type and run the following command: dotnet ef database update. With the baseline in place, we can go ahead an implement our code changes.
This is where you can add new tables, columns etc to your code-first model. Once you're happy with the code changes, you need to apply these changes to the database to be able to run and test your code.For example, they create migrationsapply migrations, and generate code for a model based on an existing database.
The commands are an extension to the cross-platform dotnet command, which is part of the. These tools work with. NET Core projects. Most developers will install dotnet ef as a global tool with the following command:. You can also use dotnet ef as local tool.
To use it as a local tool, restore the dependencies of a project that declares it as a tooling dependency using a tool manifest file. Install the. Install the current. This is all that is needed for ASP. NET Core 2. Design package is included in the Microsoft. App metapackage. The dotnet ef commands are included in the. Design package. Configure the application to use the 2. This file is normally included in the solution directory one above the project. Edit the project file and add Microsoft.
Specify the latest 1. See the project file example at the end of this section.
Subscribe to RSS
Install the latest 1. Design package, for example:. This restriction is especially useful for packages that are typically only used during development. The project is also known as the target project because it's where the commands add or remove files. By default, the project in the current directory is the target project. You can specify a different project as target project by using the --project option.
The startup project is the one that the tools build and run. The tools have to execute application code at design time to get information about the project, such as the database connection string and the configuration of the model. By default, the project in the current directory is the startup project. You can specify a different project as startup project by using the --startup-project option.
The startup project and target project are often the same project.For example, they create migrationsapply migrations, and generate code for a model based on an existing database. These tools work with both. NET Framework and. NET Core projects. The CLI tools are cross-platform and run inside a command prompt. The procedures for installing and updating the tools differ between ASP.
NET Core 2. The tools are automatically included in an ASP. Tools package is included in the Microsoft. App metapackage.
To make sure that you're getting the latest version of the tools, we recommend that you also do the following step:. Edit your. Tools package. For example, the. The EF Core tools version '2. Update the tools for the latest features and bug fixes. The project is also known as the target project because it's where the commands add or remove files.
By default, the Default project selected in Package Manager Console is the target project. You can specify a different project as target project by using the --project option. The startup project is the one that the tools build and run. The tools have to execute application code at design time to get information about the project, such as the database connection string and the configuration of the model.
By default, the Startup Project in Solution Explorer is the startup project.In this tutorial, you create a. You can follow the tutorial by using Visual Studio on Windows, or by using the. View this article's sample on GitHub. This tutorial uses SQLite because it runs on all platforms that. NET Core supports. For a list of available providers, see Database Providers. Tip: You can also install packages by right-clicking on the project and selecting Manage NuGet Packages.
EF Core can also reverse engineer a model from an existing database. Tip: In a real app, you put each class in a separate file and put the connection string in a configuration file or environment variable. To keep the tutorial simple, everything is contained in one file.
The following steps use migrations to create a database. This installs dotnet ef and the design package which is required to run the command on a project. The migrations command scaffolds a migration to create the initial set of tables for the model. The database update command creates the database and applies the new migration to it. The Add-Migration command scaffolds a migration to create the initial set of tables for the model. The Update-Database command creates the database and applies the new migration to it.
Visual Studio uses an inconsistent working directory when running. NET Core console apps. To update the working directory:. You may also leave feedback directly on GitHub. Skip to main content. Exit focus mode.
Prerequisites Install the following software:. Visual Studio version Design dotnet ef migrations add InitialCreate dotnet ef database update This installs dotnet ef and the design package which is required to run the command on a project. Is this page helpful?
Yes No. Any additional feedback? Skip Submit. Send feedback about This product This page. This page.