using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Threading;
using NewLife;
using XCode.Cache;
using XCode.Configuration;
using XCode.DataAccessLayer;
using XCode.Shards;
namespace XCode
{
public partial class Entity<TEntity>
{
/// <summary>实体元数据</summary>
public static class Meta
{
static Meta()
{
// 避免实际应用中，直接调用Entity.Meta的静态方法时，没有引发TEntity的静态构造函数。
var entity = new TEntity();
}
#region 主要属性
/// <summary>实体类型</summary>
public static Type ThisType => typeof(TEntity);
//private static IEntityFactory _Factory;
/// <summary>实体操作者</summary>
public static IEntityFactory Factory
{
get
{
// 不能缓存Factory，因为后期可能会改变注册，比如Menu
//if (_Factory != null) return _Factory;
var type = ThisType;
if (type.IsInterface) return null;
return /*_Factory = */type.AsFactory();
}
}
#endregion
#region 基本属性
private static readonly Lazy<TableItem> _Table = new(() => TableItem.Create(ThisType));
/// <summary>表信息</summary>
public static TableItem Table => _Table.Value;
private static readonly AsyncLocal<String> _ConnName = new();
/// <summary>链接名。线程内允许修改，修改者负责还原。若要还原默认值，设为null即可</summary>
public static String ConnName
{
get => _ConnName.Value ??= Table.ConnName;
set { _Session.Value = null; _ConnName.Value = value; }
}
private static readonly AsyncLocal<String> _TableName = new();
/// <summary>表名。线程内允许修改，修改者负责还原</summary>
public static String TableName
{
get => _TableName.Value ??= Table.TableName;
set { _Session.Value = null; _TableName.Value = value; }
}
/// <summary>所有数据属性</summary>
public static FieldItem[] AllFields => Table.AllFields;
/// <summary>所有绑定到数据表的属性</summary>
public static FieldItem[] Fields => Table.Fields;
/// <summary>字段名集合，不区分大小写的哈希表存储，外部不要修改元素数据</summary>
public static ICollection<String> FieldNames => Table.FieldNames;
/// <summary>唯一键，返回第一个标识列或者唯一的主键</summary>
public static FieldItem Unique
{
get
{
var dt = Table;
if (dt.PrimaryKeys.Length == 1) return dt.PrimaryKeys[0];
if (dt.Identity != null) return dt.Identity;
return null;
}
}
/// <summary>主字段。主字段作为业务主要字段，代表当前数据行意义</summary>
public static FieldItem Master => Table.Master ?? Unique;
#endregion
#region 会话
private static readonly AsyncLocal<EntitySession<TEntity>> _Session = new();
/// <summary>实体会话。线程静态</summary>
public static EntitySession<TEntity> Session => _Session.Value ??= EntitySession<TEntity>.Create(ConnName, TableName);
#endregion
#region 事务保护
/// <summary>开始事务</summary>
/// <returns>剩下的事务计数</returns>
//[Obsolete("=>Session")]
[EditorBrowsable(EditorBrowsableState.Never)]
public static Int32 BeginTrans() => Session.BeginTrans();
/// <summary>提交事务</summary>
/// <returns>剩下的事务计数</returns>
//[Obsolete("=>Session")]
[EditorBrowsable(EditorBrowsableState.Never)]
public static Int32 Commit() => Session.Commit();
/// <summary>回滚事务，忽略异常</summary>
/// <returns>剩下的事务计数</returns>
//[Obsolete("=>Session")]
[EditorBrowsable(EditorBrowsableState.Never)]
public static Int32 Rollback() => Session.Rollback();
/// <summary>创建事务</summary>
public static EntityTransaction CreateTrans() => new EntityTransaction<TEntity>();
#endregion
#region 辅助方法
///// <summary>格式化关键字</summary>
///// <param name="name">名称</param>
///// <returns></returns>
//public static String FormatName(String name) => Session.Dal.Db.FormatName(name);
///// <summary>格式化时间</summary>
///// <param name="dateTime"></param>
///// <returns></returns>
//public static String FormatDateTime(DateTime dateTime) => Session.Dal.Db.FormatDateTime(dateTime);
///// <summary>格式化数据为SQL数据</summary>
///// <param name="name">名称</param>
///// <param name="value">数值</param>
///// <returns></returns>
//public static String FormatValue(String name, Object value) => FormatValue(Table.FindByName(name), value);
///// <summary>格式化数据为SQL数据</summary>
///// <param name="field">字段</param>
///// <param name="value">数值</param>
///// <returns></returns>
//public static String FormatValue(FieldItem field, Object value) => Session.Dal.Db.FormatValue(field?.Field, value);
#endregion
#region 缓存
/// <summary>实体缓存</summary>
/// <returns></returns>
//[Obsolete("=>Session")]
//[EditorBrowsable(EditorBrowsableState.Never)]
public static EntityCache<TEntity> Cache => Session.Cache;
/// <summary>单对象实体缓存。</summary>
//[Obsolete("=>Session")]
//[EditorBrowsable(EditorBrowsableState.Never)]
public static ISingleEntityCache<Object, TEntity> SingleCache => Session.SingleCache;
/// <summary>总记录数，小于1000时是精确的，大于1000时缓存10分钟</summary>
//[Obsolete("=>Session")]
//[EditorBrowsable(EditorBrowsableState.Never)]
public static Int32 Count => (Int32)Session.LongCount;
#endregion
#region 分表分库
/// <summary>分表分库策略</summary>
public static IShardPolicy ShardPolicy { get; set; }
/// <summary>创建分库会话，using结束时自动还原</summary>
/// <param name="connName">连接名</param>
/// <param name="tableName">表名</param>
/// <returns></returns>
public static IDisposable CreateSplit(String connName, String tableName) => new SplitPackge(connName, tableName);
/// <summary>针对实体对象自动分库分表</summary>
/// <param name="entity"></param>
/// <returns></returns>
public static IDisposable CreateShard(TEntity entity)
{
// 使用自动分表分库策略
var model = ShardPolicy?.Shard(entity);
if (model != null) return new SplitPackge(model.ConnName, model.TableName);
return null;
}
/// <summary>为实体对象、时间、雪花Id等计算分表分库</summary>
/// <param name="value"></param>
/// <returns></returns>
public static IDisposable CreateShard(Object value)
{
// 使用自动分表分库策略
var model = ShardPolicy?.Shard(value);
if (model == null) return null;
return new SplitPackge(model.ConnName, model.TableName);
}
/// <summary>针对时间区间自动分库分表，常用于多表顺序查询，支持倒序</summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <param name="callback"></param>
/// <returns></returns>
public static IEnumerable<T> AutoShard<T>(DateTime start, DateTime end, Func<T> callback)
{
// 使用自动分表分库策略
var models = ShardPolicy?.Shards(start, end);
if (models == null) yield break;
foreach (var shard in models)
{
// 如果目标分表不存在，则不要展开查询
var dal = !shard.ConnName.IsNullOrEmpty() ? DAL.Create(shard.ConnName) : Session.Dal;
if (!dal.TableNames.Contains(shard.TableName)) continue;
using var split = new SplitPackge(shard.ConnName, shard.TableName);
var rs = callback();
if (!Equals(rs, default)) yield return rs;
}
}
private class SplitPackge : IDisposable
{
/// <summary>连接名</summary>
public String ConnName { get; set; }
/// <summary>表名</summary>
public String TableName { get; set; }
public SplitPackge(String connName, String tableName)
{
ConnName = Meta.ConnName;
TableName = Meta.TableName;
Meta.ConnName = connName;
Meta.TableName = tableName;
}
public void Dispose()
{
Meta.ConnName = ConnName;
Meta.TableName = TableName;
}
}
#endregion
#region 模块
internal static EntityModules _Modules = new(typeof(TEntity));
/// <summary>实体模块集合</summary>
public static EntityModules Modules => _Modules;
#endregion
}
}
}
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