C#ORM（反射+泛型）参考范例

使用控制台：

1.数据库字符串

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
    </startup>
  <appSettings>
    <add key="IDBConfig" value="T2.SQLServer;T2.SQLServer.SQLServerHelper"/>
    <add key="UserDbContext" value="Data Source=.;Database=Test;Uid=sa;Pwd=sa" />
  </appSettings>
  <connectionStrings>
    <add name="DbContext" connectionString="Data Source=.;Database=Test;Uid=sa;Pwd=sa" providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

2.方法

public class SQLHelper
    {
        private static string dbConnStr = ConfigurationManager.ConnectionStrings["DbContext"].ToString();
        public static T Find<T>(int id)
        {
            Type type = typeof(T);
            object obj = Activator.CreateInstance(type);
            var propNames = type.GetProperties().Select(c => $"{c.Name}");
            string props = string.Join(",", propNames);
            string sql = $"SELECT { props } FROM [{ type.Name }] WHERE ID={id}";
            using (SqlConnection conn = new SqlConnection(dbConnStr))
            {
                SqlCommand sqlCommand = new SqlCommand(sql,conn);
                conn.Open();
                SqlDataReader reader = sqlCommand.ExecuteReader();
                if (reader.Read())
                {
                    foreach (var prop in type.GetProperties())
                    {
                        prop.SetValue(obj,reader[prop.Name]);
                    }
                }
            }
            return (T)obj;
        }
    }

3.使用

var user = SQLHelper.Find<User>(1);

补充：

1）方法（注：调用放入Debug内的dll，但是仅限于.NET Framework，.Net Core好像不支持）

public class SimpleFactory
    {
        private static string config = ConfigurationManager.AppSettings["IDBConfig"];

        public static dynamic CreateInstentce()
        {
            Assembly assembly = Assembly.Load("T2.SQLServer");
            Type type = assembly.GetType("T2.SQLServer.SQLServerHelper");
            dynamic dynamic = Activator.CreateInstance(type);
            return dynamic;
        }
    }

2）使用

dynamic db = SimpleFactory.CreateInstentce();
db.Query();

3）说明

dynamic是动态编译（不至于一开始就让编译器报错），程序执行后采取判断有没有Query方法