ASP.NET MVC4：IQueryable的不包含定义“添加” [英] ASP.NET MVC4: IQueryable does not contain a definition for 'Add'

问题描述

我试图让一个MVC新闻系统。我开始使用这是用来创建雇员的部门一个pluralsight教程。我改变了主意，适合我自己的目的，改变了部门类别和员工newspost。这一切都优秀作品，但是现在我想删除的类别，因为我不需要为我的新闻系统类。但我可以使用的EntityFramework当我这样做不添加到数据库中。

I have tried to make an MVC news system. I started by the use a pluralsight tutorial which was used to create a department with employees. I changed the idea to fit my own purposes, changing the departments to "category" and employees to "newspost". This all works out fine, but now I want to remove the categories, since I don't need categories for my news system. But I can't add to the database using entityframework when I do this.

我有一个看起来像这样的数据源的接口：

I have an interface for the datasource that looks like this:

INewMvcSiteDataSource

public interface INewMvcSiteDataSource
{
    IQueryable<NewsPost> NewsPosts { get; }

    void Save();
}

这是我的数据库上下文类继承的：

This is inherited by my DB Context class:

NewMvcSiteDb

public class NewsMvcSiteDb : DbContext, INewMvcSiteDataSource
{
    public NewsMvcSiteDb() : base("DefaultConnection")
    {
    }

    public DbSet<NewsPost> NewsPosts { get; set; }

    IQueryable<NewsPost> INewMvcSiteDataSource.NewsPosts
    {
        get { return NewsPosts; }
    }

    public void Save()
    {
        SaveChanges();
    }
}

然后我想用它的控制器到newspost添加到数据库：

I then want to use it in the controller to add a newspost to the database:

NewsController

var newsPost = new NewsPost()
                    {
                        Subject = newsModel.Subject,
                        Content = newsModel.Content,
                        ImagePath = newsModel.ImagePath
                    };
_db.NewsPosts.Add(newsPost);
_db.Save();

但是，这是在ADD失败消息：System.Linq.IQueryable不包含添加的定义，并没有扩展方法'添加'接受一个类型的第一个参数'System.Linq的.IQueryable'可以找到（是否缺少using指令或程序集引用？）的

现在的错误说其因使用IQueryable的，但我不知道怎么回事做到这一点。

Now as the error says, its caused by using IQueryable, but I have no idea how else to do it.

你们能帮忙吗？

感谢。

推荐答案

如果你不介意通过你的接口暴露DbSet（有些人不喜欢ORM出血到应用程序），你应该能够做到以下内容：

If you don't mind exposing DbSet via your interface (some people don't like the ORM bleeding into the application),you should be able to do the following:

public interface INewMvcSiteDataSource
{
    DbSet<NewsPost> NewsPosts { get; }

    void Save();
} 



public class NewsMvcSiteDb : DbContext, INewMvcSiteDataSource
{
    public NewsMvcSiteDb() : base("DefaultConnection")
    {
    }

    public DbSet<NewsPost> NewsPosts { get; set; }

    public void Save()
    {
        SaveChanges();
    }
}

这篇关于ASP.NET MVC4：IQueryable的不包含定义“添加”的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！