简易orm 主要是为了旧平台查询方便

Posted 2020-12-21 jiamiemie

直接新建个文件即可

ExLogic.cs

	public class ExLogic
	{


		public static int Execute(string sqlCommand, string dbConnection = "WebDb")
		{
			Database db = DatabaseFactory.CreateDatabase(dbConnection);
			DbCommand dbCommand = db.GetSqlStringCommand(sqlCommand);
			try
			{
				return Convert.ToInt32(db.ExecuteScalar(dbCommand));
			}
			catch (Exception ex)
			{
				Logging.WriteLog(ex);
				throw ex;
			}

		}



		/// <summary>
		/// 获取对象
		/// </summary>
		/// <typeparam name="T">对象</typeparam>
		/// <param name="where">非必填</param>
		/// <returns></returns>
		public static T Get<T>(Expression<Func<T, bool>> where = null, string dbConnection = "WebDb") where T : class, new()
		{
			var whereSql = LambdaToSqlHelper.GetWhereSql(where);

			Database db = DatabaseFactory.CreateDatabase(dbConnection);
			string sqlCommand = $"SELECT * FROM {typeof(T).Name} WHERE " + (where == null ? "1==1" : whereSql);
			DbCommand dbCommand = db.GetSqlStringCommand(sqlCommand);
			try
			{
				var res = new T();
				using (IDataReader dr = db.ExecuteReader(dbCommand))
				{
					if (dr.Read())
					{
						var typeoft = typeof(T);
						var proper = typeoft.GetProperties();
						foreach (var item in proper)
						{
							if (item.PropertyType == typeof(int))
								item.SetValue(res, DataReaderHelper.GetInt32(dr, item.Name), null);
							else if (item.PropertyType == typeof(long))
								item.SetValue(res, DataReaderHelper.GetInt64(dr, item.Name), null);
							else if (item.PropertyType == typeof(string))
								item.SetValue(res, DataReaderHelper.GetString(dr, item.Name), null);
							else if (item.PropertyType == typeof(bool))
								item.SetValue(res, DataReaderHelper.GetBoolean(dr, item.Name), null);
							else if (item.PropertyType == typeof(decimal))
								item.SetValue(res, DataReaderHelper.GetDecimal(dr, item.Name), null);
							else if (item.PropertyType == typeof(double))
								item.SetValue(res, DataReaderHelper.GetDouble(dr, item.Name), null);
							else if (item.PropertyType == typeof(DateTime))
								item.SetValue(res, DataReaderHelper.GetDateTime(dr, item.Name), null);
						}
					}
				}
				return res;
			}
			catch (Exception ex)
			{
				throw;
			}
		}


		  



	}

/// <summary>
		/// 这部分代码网上可找,自行百度 ,我有稍作修改
		/// </summary>
	public static class LambdaToSqlHelper
	{


		#region 基础方法

		#region 获取条件语句方法

		public static string GetWhereSql<T>(Expression<Func<T, bool>> func) where T : class
		{
			string res;
			if (func.Body is BinaryExpression)
			{
				//起始参数

				BinaryExpression be = ((BinaryExpression)func.Body);
				res = BinarExpressionProvider(be.Left, be.Right, be.NodeType);
			}
			else if (func.Body is MethodCallExpression)
			{
				MethodCallExpression be = ((MethodCallExpression)func.Body);
				res = ExpressionRouter(func.Body);
			}
			else
			{
				res = " ";
			}

			return res;
		}

		#endregion 获取条件语句方法



		#region 获取排序语句 order by

		public static string GetOrderSql<T>(Expression<Func<T, object>> exp) where T : class
		{
			var res = "";
			if (exp.Body is UnaryExpression)
			{
				UnaryExpression ue = ((UnaryExpression)exp.Body);
				res = "order by `" + ExpressionRouter(ue.Operand).ToLower() + "`";
			}
			else
			{
				MemberExpression order = ((MemberExpression)exp.Body);
				res = "order by `" + order.Member.Name.ToLower() + "`";
			}
			return res;
		}

		#endregion 获取排序语句 order by



		#endregion 基础方法

		#region 底层

		public static bool In<T>(this T obj, T[] array)
		{
			return true;
		}

		public static bool NotIn<T>(this T obj, T[] array)
		{
			return true;
		}

		public static bool Like(this string str, string likeStr)
		{
			return true;
		}

		public static bool NotLike(this string str, string likeStr)
		{
			return true;
		}

		private static string GetValueStringByType(object oj)
		{
			if (oj == null)
			{
				return "null";
			}
			else if (oj is ValueType)
			{
				return oj.ToString();
			}
			else if (oj is string || oj is DateTime || oj is char)
			{
				return string.Format("‘{0}‘", oj.ToString());
			}
			else
			{
				return string.Format("‘{0}‘", oj.ToString());
			}
		}

		private static string BinarExpressionProvider(Expression left, Expression right, ExpressionType type)
		{
			var sb = string.Empty;
			//先处理左边
			string reLeftStr = ExpressionRouter(left);
			sb += reLeftStr;

			sb += ExpressionTypeCast(type);

			//再处理右边
			string tmpStr = ExpressionRouter(right);
			if (tmpStr == "null")
			{
				if (sb.EndsWith(" ="))
				{
					sb = sb.Substring(0, sb.Length - 2) + " is null";
				}
				else if (sb.EndsWith("<>"))
				{
					sb = sb.Substring(0, sb.Length - 2) + " is not null";
				}
			}
			else
			{
				//添加参数
				sb += tmpStr;
			}

			return sb;
		}

		private static string ExpressionRouter(Expression exp)
		{
			string sb = string.Empty;

			if (exp is BinaryExpression)
			{
				BinaryExpression be = ((BinaryExpression)exp);
				return BinarExpressionProvider(be.Left, be.Right, be.NodeType);
			}
			else if (exp is MemberExpression)
			{
				MemberExpression me = ((MemberExpression)exp);
				if (!exp.ToString().StartsWith("value"))
				{
					return me.Member.Name;
				}
				else
				{
					var result = Expression.Lambda(exp).Compile().DynamicInvoke();
					if (result == null)
					{
						return "null";
					}
					else
					{
						return result.ToString();
					}
				}
			}
			else if (exp is NewArrayExpression)
			{
				NewArrayExpression ae = ((NewArrayExpression)exp);
				StringBuilder tmpstr = new StringBuilder();
				foreach (Expression ex in ae.Expressions)
				{
					tmpstr.Append(ExpressionRouter(ex));
					tmpstr.Append(",");
				}
				//添加参数

				return tmpstr.ToString(0, tmpstr.Length - 1);
			}
			else if (exp is MethodCallExpression)
			{
				MethodCallExpression mce = (MethodCallExpression)exp;
				string par = ExpressionRouter(mce.Arguments[0]);
				if (mce.Method.Name == "Like")
				{
					//添加参数用
					return string.Format("({0} like {1})", par, ExpressionRouter(mce.Arguments[1]));
				}
				else if (mce.Method.Name == "NotLike")
				{
					//添加参数用
					return string.Format("({0} Not like {1})", par, ExpressionRouter(mce.Arguments[1]));
				}
				else if (mce.Method.Name == "In")
				{
					//添加参数用
					return string.Format("{0} In ({1})", par, ExpressionRouter(mce.Arguments[1]));
				}
				else if (mce.Method.Name == "NotIn")
				{
					//添加参数用
					return string.Format("{0} Not In ({1})", par, ExpressionRouter(mce.Arguments[1]));
				}
			}
			else if (exp is ConstantExpression)
			{
				ConstantExpression ce = ((ConstantExpression)exp);
				if (ce.Value == null)
				{
					return "null";
				}
				else
				{

					return $"‘{ce.Value.ToString()}‘";

				}

				//对数值进行参数附加
			}
			else if (exp is UnaryExpression)
			{
				UnaryExpression ue = ((UnaryExpression)exp);

				return ExpressionRouter(ue.Operand);
			}
			return null;
		}

		private static string ExpressionTypeCast(ExpressionType type)
		{
			switch (type)
			{
				case ExpressionType.And:
				case ExpressionType.AndAlso:
					return " AND ";

				case ExpressionType.Equal:
					return " =";

				case ExpressionType.GreaterThan:
					return " >";

				case ExpressionType.GreaterThanOrEqual:
					return ">=";

				case ExpressionType.LessThan:
					return "<";

				case ExpressionType.LessThanOrEqual:
					return "<=";

				case ExpressionType.NotEqual:
					return "<>";

				case ExpressionType.Or:
				case ExpressionType.OrElse:
					return " Or ";

				case ExpressionType.Add:
				case ExpressionType.AddChecked:
					return "+";

				case ExpressionType.Subtract:
				case ExpressionType.SubtractChecked:
					return "-";

				case ExpressionType.Divide:
					return "/";

				case ExpressionType.Multiply:
				case ExpressionType.MultiplyChecked:
					return "*";

				default:
					return null;
			}
		}

		#endregion 底层
	}

　　使用

 

var entity=ExLogic.Get<DeviceNbIotMapping>(s => s.id == id);//返回单个
//需要返回列表等功能自行扩展