EF代码首先：如何以一对多关系种植表格？ [英] EF Code First: how to seed tables in a One-To-Many relationship?

问题描述

这是我的模型

public class Movie
{
    public int MovieID { get; set; }

    public int GenreID { get; set; }

    [Required, StringLength(200)]
    public string Title { get; set; }

    public int MovieLength { get; set; }

    [Required, StringLength(1000)]
    public string MovieSummary { get; set; }

    public virtual Genre Genre { get; set; }

}

public class Genre
{
    public int GenreID { get; set; }
    public string GenreName { get; set; }

    public virtual IEnumerable<Movie> Movies { get; set; }
}

public class ZimelleShopDbContext : DbContext
{
    public DbSet<Movie> Movies { get; set; }
    public DbSet<Genre> Genres { get; set; }
}

ScottGu已经写了一个教程，显示如何种子表。我想知道如何种上上面的例子，以便在一对多关系中使用这两个表。

ScottGu has written a Tutorial that shows how to seed a table. I'd like to know how to seed the above example with in case of those 2 tables in One-To-Many relationship.

感谢您的帮助

编辑

我做到了另一回事，它的工作。我唯一需要照顾的是实例化ICollection。

I did it the other way around, and it worked. The only thing I had to take care of is to instantiate the ICollection.

public class Genre
{
    public Genre()
    {
        Movies = new List<Movie>();
    }

    //...
}

然后我做了这个

protected override void Seed(ZimelleShopDbContext context)
    {
        var genre = new Genre { GenreName = "Foo" };
        var movie = new Movie { Title = "Bar", MovieSummary = "Baz" };

        genre.Movies.Add(movie);
        context.Genres.Add(genre);
        context.SaveChanges();
    }

它仍然有效。

推荐答案

您需要替换 IEnumerable< Movie>电影与 ICollection< Movie>电影因为 IEnumerable 不是收集界面。

You need to replace IEnumerable<Movie> Movies with ICollection<Movie> Movies because IEnumerable is not a collection interface.

public class Genre
{
    public int GenreID { get; set; }
    public string GenreName { get; set; }

    public virtual ICollection<Movie> Movies { get; set; }
}

在您的初始化程序中

protected override void Seed(ZimelleShopDbContext context)
{
     var genre = new Genre { GenreName = "Foo" };
     var movie = new Movies { Title = "Bar", MovieSummary = "Baz", Genre = genre };

     context.Movies.Add(movie);

     context.SaveChanges ();
}

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