如何将ASPNETCORE_ENVIRONMENT设置为生产？ [英] How do I set ASPNETCORE_ENVIRONMENT to production?

问题描述

你好，我正在尝试在Windows计算机和 SQL Server EF核心迁移 -core-3-simple-api-for-authentication-registration-and-user-management＃user-model-cs rel = nofollow noreferrer>教学课程我要说的是运行命令

Hello I am trying to do a SQL Server EF Core Migration on a Windows computer and the tutorial I am following says to run the command

set ASPNETCORE_ENVIRONMENT =生产

当我收到以下消息时：

dotnet ef迁移添加InitialCreate --context DataContext --output-dir迁移/ SqlServerMigrations

得到消息：

Build started...
Build succeeded.

An error occurred while accessing the Microsoft.Extensions.Hosting services.
Continuing without the application service provider. 
Error: Object reference not set to an instance of an object.

Unable to create an object of type 'DataContext'. 
For the different patterns supported at design time, 
see https://go.microsoft.com/fwlink/?linkid=851728

本教程说，此错误将来自未将环境设置为生产环境。我已经尝试运行上面列出的set命令，但是它似乎没有用。我的 launchSettings.json 中的环境变量没有变化。当我在 launchSettings.json 中将环境变量手动更改为生产时，migrations命令仍然不起作用。

The tutorial says that this error will come from not setting the environment to production. I have tried to run the set command listed above, but it doesn't appear to work. The environment variables in my launchSettings.json don't change. When I manually change the environment variable to production in launchSettings.json, the migrations command still doesn't work.

我有两个问题，是 set ASPNETCORE_ENVIRONMENT =生产要运行正确的命令？如果我需要手动更改它，除了launchSettings.json之外，还需要更改其他地方吗？

I have two questions, is set ASPNETCORE_ENVIRONMENT=Production the correct command to run? If I need to change it manually, where else other than launchSettings.json do I need to change?

作为参考，这是DataContext类的样子：

For reference, this is what the DataContext class looks like:

 public class DataContext : DbContext
    {
        protected readonly IConfiguration Configuration;

        public DataContext(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        protected override void OnConfiguring(DbContextOptionsBuilder options)
        {
            // connect to sql server database
            string conString = Configuration.GetConnectionString("WebApiDatabase");
            options.UseSqlServer(conString);
        }

        public DbSet<User> Users { get; set; }
    }

并在我的appsettings.json文件中（没有真正的细节，但格式相同）：

and in my appsettings.json file (no real details, but same format):

"ConnectionStrings": {
    "WebApiDatabase": "Data Source=dbServer;Initial Catalog=fakeDb;User ID=admin;Password=password"
  }

我正在使用 3.1.402 作为 .net核心SDK 。我为 entity框架核心库安装了版本 3.1.8 。谢谢！

I am using 3.1.402 as the version for the .net core sdk. I have version 3.1.8 installed for the entity framework core library. Thank you!

推荐答案

当EF核心无法创建您的DbContext实例时，就会发生这种情况。尝试将以下类添加到您的项目中：

This happens when EF core is not able to create an instance of your DbContext. Try adding the following class to your project:

/// <summary>
/// Database context factory to be used during EF migrations.
/// </summary>
public class DataContextFactory : IDesignTimeDbContextFactory<DataContext>
{
    /// <summary>
    /// Creates a <see cref="DataContext"/>.
    /// </summary>
    /// <param name="args">Arguments.</param>
    /// <returns>Database context.</returns>
    public DataContext CreateDbContext(string[] args)
    {
        // NOTE:
        // Right now, database migration can only be performed on Windows.
        // A file called "temp.db" will be placed on the desktop and can be deleted after migration.

        var builder = new DbContextOptionsBuilder<DataContext>();

        builder.UseSqlite($"Data Source={Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory), "temp.db")}");

        return new DataContext(builder.Options);
    }
}

这应提供创建数据库所需的功能。在创建过程中，将在桌面上放置一个名为temp.db的文件。

This should provide the required functionality for creating the database. During creation a file called temp.db will be placed on your desktop.

根据需要更改数据库类型（UseSqlite）以及数据库文件的名称和路径。

Change the database type (UseSqlite) and the name and path of the database file according to your needs.

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