创建一个基类BaseEntity:
public class BaseEntity
{
[PrimaryKey]
public int Id { get; set; }
public DateTime CreateTime { get; set; }
public Status Status { get; set; }
public string Remark { get; set; }
}
/// <summary>
/// 自增主键标识
/// </summary>
public class PrimaryKey : Attribute
{
}
然后创建一个泛型底层类，这里用的数据库是mysql,如果是其它数据库，需要注意相应的关键字，比如sqlserver中user表在写sql时需要写成“[user]”。
/// <summary>
/// 已实现增删改查的底层基类 T类的属性需要和表字段保持一致
/// </summary>
/// <typeparam name="T"></typeparam>
public class BaseAccessory<T> where T : BaseEntity, new()
{
protected DBHelper dBHelper = new DBHelper();
private Type Type;
private PropertyInfo[] Props;
private PropertyInfo KeyProp;//主键属性
/// <summary>
/// 构造函数
/// </summary>
public BaseAccessory()
{
Type = typeof(T);
//下一步 将类型对应的属性写入缓存
Props = Type.GetProperties();
KeyProp = Props.First(f => f.CustomAttributes.Count(d => d.AttributeType == typeof(PrimaryKey)) > 0);
}
/// <summary>
/// 根据主键获取实体数据
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
public T GetModel(int keyValue)
{
var sql = $"select {string.Join(",", Props.Select(f => f.Name))} from {Type.Name} where {KeyProp.Name} = {keyValue}";
var cmd = dBHelper.GetSqlStringCommond(sql);
using (var reader = dBHelper.ExecuteReader(cmd))
{
while (reader.Read())
{
var t = new T();
foreach (var prop in Props)
{
prop.SetValue(t, reader[prop.Name]);
}
return t;
}
}
return null;
}
/// <summary>
/// 更新实体
/// </summary>
/// <param name="model"></param>
/// <returns>受影响的行数</returns>
public int Update(T model, Trans t = null)
{
var sql = $"UPDATE {Type.Name} SET {string.Join(",", Props.Select(f => f.Name + "=‘" + f.GetObjValue(model) + "‘"))} where {KeyProp.Name}={KeyProp.GetValue(model)} ";
var cmd = dBHelper.GetSqlStringCommond(sql);
if (t is null) { return dBHelper.ExecuteNonQuery(cmd); }
else { return dBHelper.ExecuteNonQuery(cmd, t); }
}
/// <summary>
/// 写入实体
/// </summary>
/// <param name="model"></param>
/// <returns>受影响的行数</returns>
public int Insert(T model, Trans t = null)
{
var sql = [email protected]"INSERT INTO {Type.Name} ({string.Join(",", Props.Where(f => f.Name != KeyProp.Name).Select(f => f.Name))}) VALUES({string.Join(",", Props.Where(f => f.Name != KeyProp.Name).Select(f => "‘" + f.GetObjValue(model) + "‘"))}); select @@IDENTITY";
var cmd = dBHelper.GetSqlStringCommond(sql);
object id;
if (t is null) { id = dBHelper.ExecuteScalar(cmd); }
else { id = dBHelper.ExecuteScalar(cmd, t); }
return Convert.ToInt32(id);
}
public int Delete(int keyValue, Trans t = null)
{
var sql = $"delete {Type.Name} where {KeyProp.Name} = {keyValue}";
var cmd = dBHelper.GetSqlStringCommond(sql);
if (t is null) { return dBHelper.ExecuteNonQuery(cmd); }
else { return dBHelper.ExecuteNonQuery(cmd, t); }
}
}
最后在业务代码中就可以调用该类：
/// <summary>
/// 用户表实体类 属性需要和表字段保持一致
/// </summary>
public class User : BaseEntity
{
public string LoginName { get; set; }
public string Password { get; set; }
public string RealName { get; set; }
public string PhoneNumber { get; set; }
}
public class UserAccessory : BaseAccessory<User>
{
}
public class Main{
public void TestMethod1()
{
UserAccessory userDal = new UserAccessory();
var user = userDal.GetModel(2);
user.LoginName = "哈哈泛型的强大,更新成功";
userDal.Update(user);
user.LoginName = "哈哈泛型的强大，写入成功";
var id = userDal.Insert(user);
}
}