使用EF7命令时IHostingEnvironment.WebRootPath为null

本文介绍了使用EF7命令时IHostingEnvironment.WebRootPath为null的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

问题

当我尝试向代码中添加迁移时，例如:dnx ef migrations add initial，

When I try to add a migration to my code, e.g: dnx ef migrations add initial,

Startup(IHostingEnvironment env)中的env.WebRootPath为空.

在添加新的迁移或更新数据库时，这将给我带来编译错误.

This will give me compilation errors when adding a new migration or updating the database.

代码

在 Startup.cs 类中，我在构造函数中具有以下几行:

In the Startup.cs class I have these lines in the constructor:

public Startup(IHostingEnvironment env) { // ... MyStaticClass.Initialize(env.WebRootPath); // ... _hostingEnvironment = env; }

此处env.WebRootPath为空，并且在Initialize函数中将引发异常.

Here env.WebRootPath is null and in the Initialize function this throws an exception.

在 Startup.cs 的 ConfigureServices 函数中，我解决了类依赖项:

In the ConfigureServices function of the Startup.cs I resolve my class dependencies:

public void ConfigureServices(IServiceCollection services) { // ... services.AddInstance<IMyService>(new MyService(_hostingEnvironment.WebRootPath)) // Note: _hostingEnvironment is set in the Startup constructor. // ... }

注释

• 我可以很好地构建，运行和部署代码.一切正常！

• I can build, run, and deploy the code fine. Everything works!

但是我对模型进行了更改，并希望使用以下命令添加迁移:dnx ef migrations add MyMigration然后我在包管理器控制台中看到了编译错误.

However I made a change in the model and want to add a migration with this command: dnx ef migrations add MyMigration then I see the compilation errors in the package manager console.

我正在使用ASP 5 Web应用程序和Entity Framework 7

I am using ASP 5 web application, and Entity Framework 7

推荐答案

在github上有一个关于我的问题的问题报告:

There is an issue reported on github regarding my problem:

github/aspnet/EntityFramework/issues/4494

我现在在评论中使用了变通方法，看来它工作正常:

I used the workaround in the comments now it seems to be working fine:

if (string.IsNullOrWhiteSpace(_env.WebRootPath)) { env.WebRootPath = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot"); }