Migrating Configuration From ASP.NET MVC 5 to MVC

相关阅读：http://blog.developers.ba/read-config-file-in-asp-net-vnext/

原文：http://aspnetmvc.readthedocs.org/projects/mvc/en/latest/migration/migratingconfig.html

By Steve Smith, Scott Addie

In the previous article, we began migrating an ASP.NET MVC 5 project to MVC 6. In this article, we migrate the configuration feature from ASP.NET MVC 5 to ASP.NET MVC 6.

In this article:

• Setup Configuration
• Migrate Configuration Settings from web.config
• Summary

You can download the finished source from the project created in this article here.

Setup Configuration

ASP.NET 5 and ASP.NET MVC 6 no longer use the Global.asax and web.config files that previous versions of ASP.NET utilized. In earlier versions of ASP.NET, application startup logic was placed in anApplication_StartUp method within Global.asax. Later, in ASP.NET MVC 5, a Startup.cs file was included in the root of the project; and, it was called using an OwinStartupAttribute when the application started. ASP.NET 5 (and ASP.NET MVC 6) have adopted this approach completely, placing all startup logic in the Startup.cs file.

The web.config file has also been replaced in ASP.NET 5. Configuration itself can now be configured, as part of the application startup procedure described in Startup.cs. Configuration can still utilize XML files, but typically ASP.NET 5 projects will place configuration values in a JSON-formatted file, such asappsettings.json. ASP.NET 5’s configuration system can also easily access environment variables, which can provide a more secure and robust location for environment-specific values. This is especially true for secrets like connection strings and API keys that should not be checked into source control.

For this article, we are starting with the partially-migrated ASP.NET MVC 6 project from the previous article. To setup configuration using the default MVC 6 settings, add the following constructor and property to the Startup.cs class located in the root of the project:

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public Startup(IHostingEnvironment env){    // Set up configuration sources.    var builder = new ConfigurationBuilder()        .AddJsonFile("appsettings.json")        .AddEnvironmentVariables();    Configuration = builder.Build();}public IConfigurationRoot Configuration { get; set; }

Note that at this point the Startup.cs file will not compile, as we still need to add the following usingstatement:

using Microsoft.Extensions.Configuration;

Add an appsettings.json file to the root of the project using the appropriate item template:

Migrate Configuration Settings from web.config

Our ASP.NET MVC 5 project included the required database connection string in web.config, in the<connectionStrings> element. In our MVC 6 project, we are going to store this information in theappsettings.json file. Open appsettings.json, and note that it already includes the following:

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{"Data": {"DefaultConnection": {"ConnectionString": "Server=(localdb)\\MSSQLLocalDB;Database=_CHANGE_ME;Trusted_Connection=True;"}}}

In the highlighted line depicted above, change the name of the database from _CHANGE_ME. We are going to point to a new database, which will be named NewMvc6Project to match our migrated project name.

Summary

ASP.NET 5 places all startup logic for the application in a single file, in which the necessary services and dependencies can be defined and configured. It replaces the web.config file with a flexible configuration feature that can leverage a variety of file formats, such as JSON, as well as environment variables.