Question

我正在尝试明确定义多对多关系。明确地说，我的意思是我正在定义中间实体并使用Fluent API对其进行配置。以下是我的代码：

public class ContentType
{
    public Int64 Id { get; set; }
    public Guid SID { get; set; }
    public String Name { get; set; }
    public ContentType Parent { get; set; }
    public Nullable<Int64> ParentId { get; set; }
    public Category Category { get; set; }
    public Nullable<Int64> CategoryId { get; set; }
    public Boolean IsLocked { get; set; }
    public virtual ICollection<ContentTypeColumn> ContentTypeColumns { get; set; }
}

public class Column
{
    public Int64 Id { get; set; }
    public Guid SID { get; set; }
    public String SchemaName { get; set; }
    public DataType DataType { get; set; }
    public Int32 DataTypeId { get; set; }
    public virtual ICollection<ContentTypeColumn> ContentTypeColumns { get; set; }
}

public class ContentTypeColumn
{
    public Int64 Id { get; set; }
    public Int64 ColumnId { get; set; }
    public Column Column { get; set; }
    public ContentType ContentType { get; set; }
    public Int64 ContentTypeId { get; set; }
    public Boolean IsRequired { get; set; }
    public Boolean IsCalculated { get; set; }
    public String Title { get; set; }
    public Boolean IsSystem { get; set; }
    public Expression Expression { get; set; }
    public Int32 ExpressionId { get; set; }
    public virtual ICollection<ColumnRule> Rules { get; set; }
}

public class ContentTypeConfiguration : EntityTypeConfiguration<ContentType>
{
    public ContentTypeConfiguration()
    {
        this.ToTable("ContentType");
        this.Property(x => x.Id).HasColumnName("ContentTypeId").IsRequired();

        this.Property(x => x.Name).HasMaxLength(30);
        this.HasOptional(x => x.Parent)
            .WithMany()
            .HasForeignKey(x => x.ParentId);

        this.Property(x => x.SID).IsRequired();
    }
}

public class ContentTypeColumnConfiguration : EntityTypeConfiguration<ContentTypeColumn>
{
    public ContentTypeColumnConfiguration()
    {
        this.ToTable("ContentTypeColumn");
        this.HasRequired(x => x.ContentType)
            .WithMany()
            .HasForeignKey(x => x.ContentTypeId);
        this.Property(x => x.Title).HasMaxLength(50).IsRequired();
        this.Property(x => x.Id).HasColumnName("ContentTypeColumnId");
    }
}

由于某种原因，在结果ContentTypeColumn表上创建了两个外键。一个是可以为空的外键，另一个是不可为空的。我只想生成后者，我不知道可以为空的密钥来自哪里。

有什么想法吗？

Answer 1

这是错误的：

this.HasRequired(x => x.ContentType)
    .WithMany()
    .HasForeignKey(x => x.ContentTypeId);

你有反向导航属性所以你必须在WithMany中使用int或EF可能会创建两个关系：

this.HasRequired(x => x.ContentType)
    .WithMany(y => y.ContentTypeColumns)
    .HasForeignKey(x => x.ContentTypeId);

顺便说一下。根本不需要这种映射，因为它是通过默认约定自动发现的。

在实体框架5中映射与定义的中间实体的多对多关系

1 个答案: