我有这个同伴实体:
public class Post
{
public long PostId { get; private set; }
public DateTime date { get; set; }
[Required]
public string Subject { get; set; }
public User User { get; set; }
public Category Category { get; set; }
[Required]
public string Body { get; set; }
public virtual ICollection<Tag> Tags { get; private set; }
public Post()
{
Category = new Category();
}
public void AttachTag(string name, User user)
{
if (Tags.Count(x => x.Name == name) == 0)
Tags.Add(new Tag {
Name = name,
User = user
});
else
throw new Exception("Tag with specified name is already attached to this post.");
}
public Tag DeleteTag(string name)
{
Tag tag = Tags.Single(x => x.Name == name);
Tags.Remove(tag);
return tag;
}
public bool HasTags()
{
return (Tags != null || Tags.Count > 0);
}
问题在于虚拟ICollection标签{get;私人集; }
当里面没有标签时,它实际上显示为null。我无法初始化它,因为它需要是虚拟的。
如何处理实体中的空值?如何初始化标签以及在哪里?
感谢。
答案 0 :(得分:3)
您可以初始化(实际上您必须),即使它是虚拟的。这是从POCO T4模板生成的代码:
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("Csob.Arm.EntityGenerator", "1.0.0.0")]
public virtual ICollection<TransactionCodeGroup> TransactionCodeGroups
{
get
{
if (_transactionCodeGroups == null)
{
_transactionCodeGroups = new FixupCollection<TransactionCodeGroup>();
}
return _transactionCodeGroups;
}
set
{
_transactionCodeGroups = value;
}
}
private ICollection<TransactionCodeGroup> _transactionCodeGroups;
如您所见,首次调用getter时会初始化集合。