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ASP.NET MVC系列:为已有模型添加新的属性

  在模型类Movie中添加一个新的属性Rating

ASP.NET MVC系列:为已有模型添加新的属性

  重新编译重新生成解决方案,快捷键Ctrl+Shift+B;然后对去对应的视图添加新的数据,如Index.cshtml

ASP.NET MVC系列:为已有模型添加新的属性

  编辑完成,运行之后系统报了一个异常:“System.InvalidOperationException”类型的异常在 EntityFramework.dll 中发生,但未在用户代码中进行处理

ASP.NET MVC系列:为已有模型添加新的属性

  造成这个异常的原因是Movie类中比数据库中多出了一个Rating列,所以我们需要去数据库中添加上Rating字段,你只需要打开数据库文件编辑就行;

  现在我们来介绍另外一种方法:使用 Code First 迁移更新数据库;首先我们需要将App_Data文件夹下的数据库文件(Movies.mdf)删除,然后打开“程序包管理器控制台”(你可以在“工具”菜单下的“NUGet程序包管理器”中找到它),并在控制台中输入 Enable-Migrations -ContextTypeName MvcMovie.Models.MovieDBContext

ASP.NET MVC系列:为已有模型添加新的属性

  成功后你会看到解决方案中多了一个Migrations文件夹和Configuration.cs文件,数据库每次迁移都会调用Configuration类中的Seed方法,所以我们可以在该方法中对数据库做一些操作,如初始化值什么的

  现在,你还需要创建一个用于数据库迁移的 DbMigration类;在控制台中继续输入命令 add-migration Initial

ASP.NET MVC系列:为已有模型添加新的属性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

  查看数据库表结构,我们看到了新增的Rating列;现在,我们添加新的属性可以不用再删除数据库而直接添加了,只需要在控制台执行 add-migration 属性名 和 update-database 指令就行;如果在执行 update-database 过程中一直遇到错误,你可以将Migrations文件夹删除了之后重新开始做上面的操作

  http://www.asp.net/mvc/overview/older-versions/getting-started-with-aspnet-mvc4/adding-a-new-field-to-the-movie-model-and-table

 




原标题:ASP.NET MVC系列:为已有模型添加新的属性

关键词:ASP.NET

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