.net core自定义特性操作

    最近移植之前写的几个类，发现特性操作发生了一些改变。

    直接看代码，建立表和字段特性类，添加一个用户表，设置好特性。

using System;

namespace TestDemo
{
    /// <summary>
    /// 表实体特性
    /// </summary>
    [AttributeUsage(AttributeTargets.Class, Inherited = false)]
    public class TableAttribute : Attribute
    {        
        /// <summary>
        /// 数据库表名称
        /// </summary>
        public string TableName { get; set; }
        /// <summary>
        /// 数据库表注释
        /// </summary>
        public string Description { get; set; }

        public TableAttribute()
        {
            TableName = string.Empty;
            Description = string.Empty;
        }
    }
}

using System;

namespace TestDemo
{
    /// <summary>
    /// 列特性
    /// </summary>
    [AttributeUsage( AttributeTargets.Property , AllowMultiple = false)]
    public class TableColumnAttribute : Attribute
    {
        /// <summary>
        /// 列名称
        /// </summary>
        public string ColumnName { get; set; }
        /// <summary>
        /// 字段说明
        /// </summary>
        public string Description { get; set; }
        /// <summary>
        /// 是否是主键
        /// </summary>
        public bool IsPrimaryKey { get; set; }
        /// <summary>
        /// 主键是否自动增长
        /// </summary>
        public bool IsPrimaryKeyAuto { get; set; }
        /// <summary>
        /// 数据库数据类型
        /// </summary>
        public string DbDataType { get; set; }
        /// <summary>
        /// 字符串最大长度
        /// </summary>
        public int MaxLength { get; set; }
        /// <summary>
        /// 是否不可为空
        /// </summary>
        public bool NotNull { get; set; }

        public TableColumnAttribute()
        {
            ColumnName = string.Empty;
            Description = string.Empty;
            IsPrimaryKey = false;
            IsPrimaryKeyAuto = false;
            DbDataType = "varchar";
            MaxLength = 50;
            NotNull = false;
        }
    }
}

namespace TestDemo
{
    [Table(Description = "用户表", TableName = "USER")]
    public class User
    {
        [TableColumn(ColumnName = "ID", DbDataType = "int", Description = "主键", IsPrimaryKey = true, IsPrimaryKeyAuto = true, MaxLength = 0, NotNull = true)]
        public int Id { get; set; }

        [TableColumn(ColumnName = "LOGINNO", DbDataType = "varchar", Description = "登录名", IsPrimaryKey = false, IsPrimaryKeyAuto = false, MaxLength = 20, NotNull = true)]
        public string LoginNo { get; set; }

        [TableColumn(ColumnName = "USERNAME", DbDataType = "varchar", Description = "用户姓名", IsPrimaryKey = false, IsPrimaryKeyAuto = false, MaxLength = 20, NotNull = false)]
        public string UserName { get; set; }

        [TableColumn(ColumnName = "NICKNAME", DbDataType = "varchar", Description = "昵称", IsPrimaryKey = false, IsPrimaryKeyAuto = false, MaxLength = 30, NotNull = false)]
        public string NickName { get; set; }

        [TableColumn(ColumnName = "TEL", DbDataType = "varchar", Description = "电话", IsPrimaryKey = false, IsPrimaryKeyAuto = false, MaxLength = 11, NotNull = false)]
        public string Tel { get; set; }
    }
}

    获取用户表以及表字段的特性。

using System;
using System.Reflection;
using System.Text;

namespace TestDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

            TableAttribute table = GetTableAttribute<User>();
            Console.WriteLine("User(TableName:" + table.TableName + "\r\n,Description:" + table.Description + ")");
            Console.WriteLine();

            TableColumnAttribute colId = GetTableColumnAttribute<User>("Id");
            Console.WriteLine("Id(ColumnName:" + colId.ColumnName 
                + "\r\n,DbDataType:" + colId.DbDataType
                + "\r\n,Description:" + colId.Description
                + "\r\n,IsPrimaryKey:" + colId.IsPrimaryKey
                + "\r\n,IsPrimaryKeyAuto:" + colId.IsPrimaryKeyAuto
                + "\r\n,MaxLength:" + colId.MaxLength
                + "\r\n,NotNull:" + colId.NotNull + ")");
            Console.WriteLine();

            TableColumnAttribute colName = GetTableColumnAttribute<User>("UserName");
            Console.WriteLine("UserName(ColumnName:" + colName.ColumnName
                + "\r\n,DbDataType:" + colName.DbDataType
                + "\r\n,Description:" + colName.Description
                + "\r\n,IsPrimaryKey:" + colName.IsPrimaryKey
                + "\r\n,IsPrimaryKeyAuto:" + colName.IsPrimaryKeyAuto
                + "\r\n,MaxLength:" + colName.MaxLength
                + "\r\n,NotNull:" + colName.NotNull + ")");

            Console.ReadLine();
        }

        /// <summary>
        /// 获取表特性
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public static TableAttribute GetTableAttribute<T>()
        {
            Type t = typeof(T);
            TableAttribute m = t.GetTypeInfo().GetCustomAttribute<TableAttribute>();
            return m;
        }

        /// <summary>
        /// 获取列特性
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="propertyName"></param>
        /// <returns></returns>
        public static TableColumnAttribute GetTableColumnAttribute<T>(string propertyName)
        {
            TableColumnAttribute m = null;

            Type t = typeof(T);
            PropertyInfo[] arryProperty = t.GetProperties();
            if (arryProperty != null)
            {
                foreach (PropertyInfo p in arryProperty)
                {            
                    if (p.Name == propertyName)
                    {
                        m = p.GetCustomAttribute<TableColumnAttribute>();
                    }
                }
            }
            
            return m;
        }
    }
}

    运行起来看看获取的情况！