Microsoft.EntityFrameworkCore.Tools - Azure Functions with .NET 5 (Isolated) Design-time DbContext Creation with HostBuilder

问题描述

我在 Visual Studio Version 16.10.0 中使用模板 Azure Functions 和 .NET 5(隔离)和Http触发器.

然后我创建了以下文件:

博客.cs

公开课博客{公共 int Id { 获取；放;}公共字符串名称 { 获取；放;}}

ApplicationDbContext.cs

公共类 ApplicationDbContext : DbContext{公共应用程序数据库上下文(DbContextOptions选项):基础(选项){}公共数据库集博客 { 得到;放;}}

程序.cs

公共类程序{public static void Main(){var host = new HostBuilder().ConfigureFunctionsWorkerDefaults().ConfigureServices(services =>{var connectionString = Environment.GetEnvironmentVariable("ConnectionStrings:DefaultConnection");services.AddDbContext(options =>options.UseSqlServer(连接字符串，sqlServerOptions =>sqlServerOptions.CommandTimeout(600)));}).建造();主机.运行();}}

Function1.cs

公共类Function1{私有只读 ApplicationDbContext _applicationDbContext;公共功能1(ApplicationDbContext applicationDbContext){_applicationDbContext = applicationDbContext;}[功能(功能1")]public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, get", post")] HttpRequestData req,FunctionContext executionContext){var logger = executionContext.GetLogger("Function1");logger.LogInformation(C# HTTP 触发器函数处理了一个请求.");var connectionString = _applicationDbContext.Database.GetDbConnection().ConnectionString;var response = req.CreateResponse(HttpStatusCode.OK);response.Headers.Add("Content-Type", "text/plain; charset=utf-8");response.WriteString(欢迎使用 Azure 函数！");返回响应；}}

local.settings.json:

{连接字符串":{DefaultConnection":Server=(localdb)\mssqllocaldb;Database=FunctionApp1.Test;Trusted_Connection=True;MultipleActiveResultSets=true"},IsEncrypted":假，值":{AzureWebJobsStorage":UseDevelopmentStorage=true"，FUNCTIONS_WORKER_RUNTIME":dotnet 隔离"}}

host.json

{版本":2.0"，记录":{应用洞察":{采样设置":{isEnabled":真，excludedTypes":请求"}}}}

我已经通过 Program.cs 验证了依赖注入是有效的 ->新的HostBuilder

如果我在包管理器控制台中运行 Add-Migration InitialCreate，我会收到以下错误:

无法创建类型为ApplicationDbContext"的对象.为了设计时支持的不同模式，请参阅https://go.microsoft.com/fwlink/?linkid=851728

https://docs.microsoft.com/en-us/ef/core/managing-schemas/migrations/?tabs=vs

https://docs.microsoft.com/en-us/ef/core/cli/dbcontext-creation?tabs=vs

要从应用程序的服务提供者处获取 DbContext 对象，示例代码如下所示:

公共类程序{public static void Main(string[] args)=>CreateHostBuilder(args).Build().Run();//EF Core 在设计时使用此方法访问 DbContext公共静态 IHostBuilder CreateHostBuilder(string[] args)=>Host.CreateDefaultBuilder(args).ConfigureWebHostDefaults(webBuilder =>webBuilder.UseStartup());}公开课启动{public void ConfigureServices(IServiceCollection 服务)=>services.AddDbContext();公共无效配置(IApplicationBuilder 应用程序，IWebHostEnvironment 环境){}}公共类 ApplicationDbContext : DbContext{公共 ApplicationDbContext(DbContextOptions options):基础(选项){}}

工具首先尝试通过调用获取服务提供者Program.CreateHostBuilder()，调用Build()，然后访问服务属性.

有没有办法让工具与 HostBuilder 一起工作?

解决方案

几天来我遇到了类似的问题.我刚刚看了你的解决方案，它对我帮助很大.但是我没有创建一个 StartUp 类来添加数据库上下文

public static IHostBuilder CreateHostBuilder(string[] args)=>新的主机构建器().ConfigureFunctionsWorkerDefaults().ConfigureServices(service => ConfigureServices(service));

在 ConfigureServices 里面我只有:

services.AddDbContext();

它有效.

I have created a new FunctionApp in Visual Studio Version 16.10.0 using the template Azure Functions with .NET 5 (Isolated) and Http trigger.

I have then created the following files:

Blog.cs

public class Blog
{
    public int Id { get; set; }
    public string Name { get; set; }
}

ApplicationDbContext.cs

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(
        DbContextOptions<ApplicationDbContext> options) : base(options)
    {
    }

    public DbSet<Blog> Blogs { get; set; }
}

Program.cs

public class Program
{
    public static void Main()
    {
        var host = new HostBuilder()
            .ConfigureFunctionsWorkerDefaults()
            .ConfigureServices(services =>
            {
                var connectionString = Environment.GetEnvironmentVariable("ConnectionStrings:DefaultConnection");
                services.AddDbContext<ApplicationDbContext>(options =>
                        options.UseSqlServer(
                        connectionString,
                        sqlServerOptions => sqlServerOptions.CommandTimeout(600)));
            })
            .Build();

        host.Run();
    }
}

Function1.cs

public class Function1
{
    private readonly ApplicationDbContext _applicationDbContext;

    public Function1(ApplicationDbContext applicationDbContext)
    {
        _applicationDbContext = applicationDbContext;
    }

    [Function("Function1")]
    public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req,
        FunctionContext executionContext)
    {
        var logger = executionContext.GetLogger("Function1");
        logger.LogInformation("C# HTTP trigger function processed a request.");

        var connectionString = _applicationDbContext.Database.GetDbConnection().ConnectionString;

        var response = req.CreateResponse(HttpStatusCode.OK);
        response.Headers.Add("Content-Type", "text/plain; charset=utf-8");

        response.WriteString("Welcome to Azure Functions!");

        return response;
    }
}

local.settings.json:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=(localdb)\mssqllocaldb;Database=FunctionApp1.Test;Trusted_Connection=True;MultipleActiveResultSets=true"
  },
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated"
  }
}

host.json

{
    "version": "2.0",
    "logging": {
        "applicationInsights": {
            "samplingSettings": {
                "isEnabled": true,
                "excludedTypes": "Request"
            }
        }
    }
}

I have verified that dependency injection works from Program.cs -> new HostBuilder

If I run Add-Migration InitialCreate in Package Manager Console I get the following error:

https://docs.microsoft.com/en-us/ef/core/managing-schemas/migrations/?tabs=vs

https://docs.microsoft.com/en-us/ef/core/cli/dbcontext-creation?tabs=vs

To obtain the DbContext object from the application's service provider the example code looks like this:

public class Program
{
    public static void Main(string[] args)
        => CreateHostBuilder(args).Build().Run();

    // EF Core uses this method at design time to access the DbContext
    public static IHostBuilder CreateHostBuilder(string[] args)
        => Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(
                webBuilder => webBuilder.UseStartup<Startup>());
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
        => services.AddDbContext<ApplicationDbContext>();

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
    }
}

public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }
}

Is there anyway to make Tools work with HostBuilder instead?

解决方案

I had similar issue for few days now. I just watched your solution and it helped me a lot. But I didn't create a StartUp class to add database context

public static IHostBuilder CreateHostBuilder(string[] args)
        => new HostBuilder()
        .ConfigureFunctionsWorkerDefaults()
        .ConfigureServices(service => ConfigureServices(service));

Inside ConfigureServices i just have :

services.AddDbContext<ApplicationDbContext>();

and it works.

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