CTP5 - Code First不在数据库中生成关联集合 [英] CTP5 - Code First not generating associated collections in the Database

问题描述

 

采取以下简单类和关联的DbContext

Take the following simple class and associated DbContext

public class Test
{
	public Test()
	{
		Keywords = new Collection<string>();
	}

	public int Id { get; set; }
	public string Name { get; set; }
	public ICollection<string> Keywords { get; set; }
}

public class TestDbContext : DbContext
{
	public TestDbContext()
	{
		Database.Delete();
		Database.CreateIfNotExists();
	}

	public DbSet<Test> Tests { get; set; }

	protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder)
	{		
		base.OnModelCreating(modelBuilder);
	}
}

The type 'System.Collections.Generic.ICollection<string>' must be a non-nullable value type in order to use it as parameter 'T' 
in the generic type or method 'System.Data.Entity.ModelConfiguration.Configuration.Types.StructuralTypeConfiguration<TStructuralType>
.Property<T>(System.Linq.Expressions.Expression<System.Func<TStructuralType,T>>)'

Any ideas how to create the necessary table relationships between test class and the keywords property?

推荐答案

如果您在数据库术语中考虑这一点，则无法存储集合就像这样的字符串。



相反，你应该创建一个类KeyWord，并让Test类有一个KeyWords列表。

类似于：

If you think about this in database terms, it is not possible to store a collection of strings just like that.

Instead, you should create a class, KeyWord, and make the Test class have a list of KeyWords.
Something like:

 

public class Test
{
	public Test()
	{
		Keywords = new Collection<KeyWord>();
	}

	public int Id { get; set; }
	public string Name { get; set; }
	public ICollection<KeyWord> Keywords { get; set; }
}


public class KeyWord
{ <br/>
       public int Id { get; set; }
    public string Word { get; set; }
    // ..
}

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