Linq 通过反射动态查询对象

public IQueryable<TEntity> Find<TEntity>(TEntity obj) where TEntity : class
        {
            //获得所有property的信息
            PropertyInfo[] properties = obj.GetType().GetProperties(BindingFlags.Public |
 BindingFlags.Instance);
            //构造初始的query
            IQueryable<TEntity> query = this.GetTable<TEntity>().AsQueryable<TEntity>();
            //遍历每个property
            foreach (PropertyInfo p in properties)
            {
                if (p != null)
                {
                    Type t = p.PropertyType;
                    //加入object，Binary，和XDocument， 支持sql_variant，imager 和xml等的影射。
                    if (t.IsValueType || t == typeof(string) || t == typeof(System.Byte[])
                        || t == typeof(object) || t == typeof(System.Xml.Linq.XDocument)
                        || t == typeof(System.Data.Linq.Binary))
                    {
                        //如果不为null才算做条件
                        if ( p.GetValue(obj, null) != null)
                        {
                            ParameterExpression param = Expression.Parameter(typeof(TEntity), "c");
                            Expression right = Expression.Constant(p.GetValue(obj, null));
                            Expression left = Expression.Property(param, p.Name);
                            Expression filter = Expression.Equal(left,right);

                            Expression<Func<TEntity, bool>> pred = Expression.Lambda<Func
<TEntity, bool>>(filter, param);
                            query = query.Where(pred);
                        }
                    }
                }
            }
            return query;
        }

 

调用：

            Customer c = new Customer();
            c.City = "London";
            c.Phone = "23236133";

            var q = db.Find<Customer>(c).ToList();