C# 使用automapper更新实体框架时出错。角色''；关系的''；具有重数1或0..1

我正在尝试更新由automapper bind获取的模型

当我的更新函数执行时

Context.Entry(obj).State = EntityState.Modified;

实体框架引发此异常

违反了多重性约束。角色 关系的“立法类别\立法\来源” “Creci.Infra.Data.Context.legictionCategory_legictions”已 多重数1或0..1

如果我尝试在不使用automapper的情况下更新模型，效果会很好

关系是

public class LegislationCategoryMap : EntityTypeConfiguration<LegislationCategory>
    {
        public LegislationCategoryMap()
        {
            ...

            HasMany(x => x.Legislations)
                .WithRequired(x => x.Category)
                .WillCascadeOnDelete(true);
        }
    }

public class LegislationMap : EntityTypeConfiguration<Legislation>
    {
        public LegislationMap()
        {
            ...

            HasRequired(x => x.Category);
        }
    }

以及更新功能

public void Update(TEntity obj)
        {
            Validate(obj);

            using (var transaction = Context.Database.BeginTransaction())
            {
                try
                {
                    Context.Entry(obj).State = EntityState.Modified;
                    Context.SaveChanges();
                    transaction.Commit();
                }
                catch (Exception)
                {
                    transaction.Rollback();
                    throw;
                }
            }
        }

var model = Mapper.Map(viewModel, repository.GetById(id));
            repository.Update(model);

public void Update(TEntity obj)
        {
            Validate(obj);

            using (var transaction = Context.Database.BeginTransaction())
            {
                try
                {
                    Context.Entry(obj).State = EntityState.Modified;
                    Context.SaveChanges();
                    transaction.Commit();
                }
                catch (Exception)
                {
                    transaction.Rollback();
                    throw;
                }
            }
        }