数据帮助类(DataHelper)

/// <summary>

        /// 是否为空...

        /// </summary>

        /// <param name="str">数据值</param>

        /// <param name="typeName">数据类型</param>

        /// <returns></returns>

        public static object ChekIsNullOrEmpty(object str,string typeName) 

        {

            switch (typeName)

            {

                case "String":

                    return str == null ? "" : str.ToString();

                case "DateTime":

                    return str == null || str.ToString() == "0001/1/1 0:00:00" ? DateTime.Parse("1990-1-1") : str;

                default:

                    return str == null ? "" : str.ToString();

            }

        }

　　

 /// <summary>

        /// 给实体类空值赋值

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <param name="model">实体类</param>

        /// <returns></returns>

        public static T ChekModelIsNullOrEmpty<T>(T model)

        {

            foreach (PropertyInfo property in typeof(T).GetProperties())

            {

                object strValue = DataHelper.ChekIsNullOrEmpty(model.GetType().GetProperty(property.Name).GetValue(model, null), property.PropertyType.Name);

                model.GetType().GetProperty(property.Name).SetValue(model, strValue, null);

            }

            return model;

        }

　　

/// <summary>

        /// 将一个列表转换成DataTable,如果列表为空将返回空的DataTable结构

        /// </summary>

        /// <typeparam name="T">要转换的数据类型</typeparam>

        /// <param name="entityList">实体对象列表</param> 

        public static DataTable EntityListToDataTable<T>(List<T> entityList)

        {

            DataTable dt = new DataTable();



            //取类型T所有Propertie

            Type entityType = typeof(T);

            PropertyInfo[] entityProperties = entityType.GetProperties();

            Type colType = null;

            foreach (PropertyInfo propInfo in entityProperties)

            {



                if (propInfo.PropertyType.IsGenericType)

                {

                    colType = Nullable.GetUnderlyingType(propInfo.PropertyType);

                }

                else

                {

                    colType = propInfo.PropertyType;

                }



                if (colType.FullName.StartsWith("System"))

                {

                    dt.Columns.Add(propInfo.Name, colType);

                }

            }



            if (entityList != null && entityList.Count > 0)

            {

                foreach (T entity in entityList)

                {

                    DataRow newRow = dt.NewRow();

                    foreach (PropertyInfo propInfo in entityProperties)

                    {

                        if (dt.Columns.Contains(propInfo.Name))

                        {

                            object objValue = propInfo.GetValue(entity, null);

                            newRow[propInfo.Name] = objValue == null ? DBNull.Value : objValue;

                        }

                    }

                    dt.Rows.Add(newRow);

                }

            }



            return dt;

        }

　　

 

/// <summary>

        /// 将一个DataTable转换成列表

        /// </summary>

        /// <typeparam name="T">实体对象的类型</typeparam>

        /// <param name="dt">要转换的DataTable</param>

        /// <returns></returns>

        public static List<T> DataTableToEntityList<T>(DataTable dt)

        {

            List<T> entiyList = new List<T>();



            Type entityType = typeof(T);

            PropertyInfo[] entityProperties = entityType.GetProperties();



            foreach (DataRow row in dt.Rows)

            {

                T entity = Activator.CreateInstance<T>();



                foreach (PropertyInfo propInfo in entityProperties)

                {

                    if (dt.Columns.Contains(propInfo.Name))

                    {

                        if (!row.IsNull(propInfo.Name))

                        {

                            propInfo.SetValue(entity, row[propInfo.Name], null);

                        }

                    }

                }



                entiyList.Add(entity);

            }



            return entiyList;

        }