问题描述
在我的数据库我有一个表的类别，与列编号，类别名称，ParentCategoryId，其中ParentCategoryId对Category.Id的约束。
In my database I have a table Category, with columns Id, CategoryName, ParentCategoryId, where ParentCategoryId has a constraint on Category.Id.
我使用的是实体框架代码首先，在实体如下：
I'm using entity framework code first, where the entity looks like:
public class Category
{
public long Id { get; private set; }
public string CategoryName { get; private set; }
public long? ParentCategoryId { get; private set; }
public Category ParentCategory { get; private set; }
public virtual ICollection<Category> SubCategories { get; private set; }
}
如果我试图运行对这一查询时，我得到的异常：
If I try to run a query against this, I get the exception:
The relationship 'ComplaintModel.FK_Complaint_Category' was not loaded because the type 'ComplaintModel.Category' is not available.\r\nThe following information may be useful in resolving the previous error:\r\nThe required property 'Category1' does not exist on the type 'EC.Complaint.Services.Command.Domain.Entities.Category'.\r\n\r\n"} System.Exception {System.Data.MetadataException}
所以，现在看来，这需要导航属性，如果我添加这些：
So it seems it needs navigation properties, if I add these:
public ICollection<Category> Category1 { get; private set; }
public long? Category2Id { get; private set; }
public Category Category2 { get; private set; }
查询工作。
但当然，我不希望组别和组别的属性，我想使用ParentCategory和子类别属性。
But of course, I don't want the Category1 and Category2 properties, I want ParentCategory and SubCategories properties being used.
我怎么能告诉代码首先要使用正确的导航属性？
How can I tell code first to use the correct navigation properties?
推荐答案
您POCO类应该是这样的...
your POCO class should look like this ...
public class Category
{
public long Id { get; private set; }
public string CategoryName { get; private set; }
public long? ParentCategoryId { get; private set; }
public virtual Category ParentCategory { get; private set; }
public virtual ICollection<Category> SubCategories { get; private set; }
}
public class CategoryConfiguration : EntityTypeConfiguration<Category>
{
public CategoryConfiguration()
{
this.HasKey(x => x.Id);
this.HasMany(category => category.SubCategories)
.WithOptional(category => category.ParentCategoryId)
.HasForeignKey(course => course.UserId)
.WillCascadeOnDelete(false);
}
}
这篇关于映射在EF代码首先自我引用实体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！