entity-framework - How to get file path in Entity Framework Seed method without HttpContext (executed from package manager command)

Question

In my entity framework Seed method I have the following line to get a file from a different project:

 var filePath = new DirectoryInfo(HostingEnvironment.ApplicationPhysicalPath).Parent.FullName + "\\Com.ProjectX\\companies.xls";

This works when a HttpContext is available, like when using this action method to trigger it:

public ActionResult About()
    {
        var configuration = new Com.EntityModel.Configuration();
        var migrator = new System.Data.Entity.Migrations.DbMigrator(configuration);
        migrator.Update();

        return View();
    }

However, it doesn't work when I execute Update-Database from the package manager console (the file isn't found and it's hard to debug because I also can't breakpoint when doing that.

I'd like to be able to use Update-Database command and have it work without an HttpContext. How can I get the path?

Answer 1

我使用这个函数来映射 Seed 方法中的路径，不是很干净，但它可以工作：

private string MapPath(string seedFile)
{
    if(HttpContext.Current!=null)
        return HostingEnvironment.MapPath(seedFile);

    var absolutePath = new Uri(Assembly.GetExecutingAssembly().CodeBase).AbsolutePath;
    var directoryName = Path.GetDirectoryName(absolutePath);
    var path = Path.Combine(directoryName, ".." + seedFile.TrimStart('~').Replace('/','\\'));

    return path;
}

然后只需使用以下命令调用它：

        using (var streamReader = new StreamReader(MapPath("~/Data/MyFile.csv")))

此外，为了调试 Seed 方法，我喜欢只抛出一个带有我想要显示的消息的异常（我是 EF 的初学者，我还没有弄清楚如何写入 NuGet 包管理器控制台:)）

Answer 2

private string GetPath(string relativeFilePath)
{
    var absolutePath = new Uri(Assembly.GetExecutingAssembly().CodeBase).AbsolutePath;
    var directoryName = Path.GetDirectoryName(absolutePath);
    var path = Path.Combine(directoryName, ".." + relativeFilePath.TrimStart('~').Replace('/', '\\'));

    return System.Web.HttpUtility.UrlDecode(path); // decode spaces in path :(
}