using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using NewLife;
using NewLife.Collections;
namespace XCode.DataAccessLayer
{
/// <summary>数据库元数据</summary>
abstract partial class DbMetaData : DisposeBase, IMetaData
{
#region 属性
private IDatabase _Database;
/// <summary>数据库</summary>
public virtual IDatabase Database { get { return _Database; } set { _Database = value; } }
private ICollection<String> _MetaDataCollections;
/// <summary>所有元数据集合</summary>
public ICollection<String> MetaDataCollections
{
get
{
if (_MetaDataCollections == null)
{
var list = new HashSet<String>(StringComparer.OrdinalIgnoreCase);
var dt = GetSchema(DbMetaDataCollectionNames.MetaDataCollections, null);
if (dt != null && dt.Rows != null && dt.Rows.Count > 0)
{
foreach (DataRow dr in dt.Rows)
{
String name = "" + dr[0];
if (!String.IsNullOrEmpty(name) && !list.Contains(name)) list.Add(name);
}
}
_MetaDataCollections = list;
}
return _MetaDataCollections;
}
}
private ICollection<String> _ReservedWords;
/// <summary>保留关键字</summary>
public virtual ICollection<String> ReservedWords
{
get
{
if (_ReservedWords == null)
{
var list = new HashSet<String>(StringComparer.OrdinalIgnoreCase);
if (MetaDataCollections.Contains(DbMetaDataCollectionNames.ReservedWords))
{
var dt = GetSchema(DbMetaDataCollectionNames.ReservedWords, null);
if (dt != null && dt.Rows != null && dt.Rows.Count > 0)
{
foreach (DataRow dr in dt.Rows)
{
String name = "" + dr[0];
if (!String.IsNullOrEmpty(name) && !list.Contains(name)) list.Add(name);
}
}
}
_ReservedWords = list;
}
return _ReservedWords;
}
}
//String _ParamPrefix;
///// <summary>参数前缀</summary>
//public String ParamPrefix
//{
// get
// {
// if (_ParamPrefix == null)
// {
// var dt = GetSchema(DbMetaDataCollectionNames.DataSourceInformation, null);
// if (dt != null && dt.Rows != null && dt.Rows.Count > 0)
// {
// String str = null;
// if (TryGetDataRowValue<String>(dt.Rows[0], DbMetaDataColumnNames.ParameterMarkerPattern, out str) ||
// TryGetDataRowValue<String>(dt.Rows[0], DbMetaDataColumnNames.ParameterMarkerFormat, out str))
// _ParamPrefix = str.StartsWith("\\") ? str.Substring(1, 1) : str.Substring(0, 1);
// }
// if (_ParamPrefix == null) _ParamPrefix = "";
// }
// return _ParamPrefix;
// }
//}
#endregion
#region GetSchema方法
/// <summary>返回数据源的架构信息</summary>
/// <param name="collectionName">指定要返回的架构的名称。</param>
/// <param name="restrictionValues">为请求的架构指定一组限制值。</param>
/// <returns></returns>
public DataTable GetSchema(string collectionName, string[] restrictionValues)
{
// 如果不是MetaDataCollections，并且MetaDataCollections中没有该集合，则返回空
if (!String.Equals(collectionName, DbMetaDataCollectionNames.MetaDataCollections, StringComparison.OrdinalIgnoreCase))
{
if (!MetaDataCollections.Contains(collectionName)) return null;
}
return Database.CreateSession().GetSchema(collectionName, restrictionValues);
}
#endregion
#region 辅助函数
/// <summary>尝试从指定数据行中读取指定名称列的数据</summary>
/// <typeparam name="T"></typeparam>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <param name="value"></param>
/// <returns></returns>
protected static Boolean TryGetDataRowValue<T>(DataRow dr, String name, out T value)
{
value = default(T);
if (dr == null || !dr.Table.Columns.Contains(name) || dr.IsNull(name)) return false;
Object obj = dr[name];
// 特殊处理布尔类型
if (Type.GetTypeCode(typeof(T)) == TypeCode.Boolean && obj != null)
{
if (obj is Boolean)
{
value = (T)obj;
return true;
}
if (String.Equals("YES", obj.ToString(), StringComparison.OrdinalIgnoreCase))
{
value = (T)(Object)true;
return true;
}
if (String.Equals("NO", obj.ToString(), StringComparison.OrdinalIgnoreCase))
{
value = (T)(Object)false;
return true;
}
}
try
{
if (obj is T)
value = (T)obj;
else
value = (T)Convert.ChangeType(obj, typeof(T));
}
catch { return false; }
return true;
}
/// <summary>获取指定数据行指定字段的值，不存在时返回空</summary>
/// <typeparam name="T"></typeparam>
/// <param name="dr"></param>
/// <param name="name"></param>
/// <returns></returns>
protected static T GetDataRowValue<T>(DataRow dr, String name)
{
T value = default(T);
if (TryGetDataRowValue<T>(dr, name, out value)) return value;
return default(T);
}
/// <summary>格式化关键字</summary>
/// <param name="name"></param>
/// <returns></returns>
protected String FormatName(String name)
{
//return Database.FormatKeyWord(keyWord);
return Database.FormatName(name);
}
/// <summary>检查并获取当前数据库的默认值。如果数据库类型一致，则直接返回false，因为没有修改</summary>
/// <param name="dc"></param>
/// <param name="oriDefault"></param>
/// <returns></returns>
protected virtual Boolean CheckAndGetDefault(IDataColumn dc, ref String oriDefault)
{
// 如果数据库类型等于原始类型，则直接通过
if (dc.Table.DbType == Database.DbType) return false;
// 原始数据库类型
var db = DbFactory.Create(dc.Table.DbType);
if (db == null) return false;
var tc = Type.GetTypeCode(dc.DataType);
// 特殊处理时间
if (tc == TypeCode.DateTime)
{
if (String.IsNullOrEmpty(oriDefault) || oriDefault.EqualIgnoreCase(db.DateTimeNow))
{
oriDefault = Database.DateTimeNow;
return true;
}
else
{
//// 出现了不支持的时间默认值
//if (DAL.Debug) DAL.WriteLog("出现了{0}不支持的时间默认值：{1}.{2}={3}", Database.DbType, dc.Table.Name, dc.Name, oriDefault);
//oriDefault = null;
//return true;
return false;
}
}
// 特殊处理Guid
else if (tc == TypeCode.String || dc.DataType == typeof(Guid))
{
// 如果字段类型是Guid，不需要设置默认值，则也说明是Guid字段
if (String.IsNullOrEmpty(oriDefault) || oriDefault.EqualIgnoreCase(db.NewGuid) ||
String.IsNullOrEmpty(db.NewGuid) && dc.DataType == typeof(Guid))
{
oriDefault = Database.NewGuid;
return true;
}
}
return false;
}
#endregion
#region 日志输出
/// <summary>输出日志</summary>
/// <param name="msg"></param>
public static void WriteLog(String msg) { DAL.WriteLog(msg); }
/// <summary>输出日志</summary>
/// <param name="format"></param>
/// <param name="args"></param>
public static void WriteLog(String format, params Object[] args) { DAL.WriteLog(format, args); }
#endregion
}
}
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