EF外键添加

public partial class YXTDemand : FullAuditedEntity<int, User>
{
    public virtual YXTOrigin Origin { get; set; }   
}
public partial class YXTOrigin : FullAuditedEntity<int, User>
{
    public virtual ICollection<YXTDemand> YXTDemands { get; set; }
}

var entity= var entity = input.MapTo<YXTDemand>();
var merchandise = await _yXTMerchandiseRepository.GetAsync(Merchandise_Id);
entity.SpecifiedOrigin = origin.OriginName;
await _yXTDemandRepository.InsertAsync(entity);