/// <summary>
/// 通过托管属性及其对应的实体类型，并通过可用的缓存列表，查找对应的 DbTable。
/// </summary>
/// <param name="property"></param>
/// <param name="propertyOwner"></param>
/// <param name="tablesCache"></param>
/// <returns></returns>
internal static RdbTable GetPropertyTable(IManagedProperty property, Type propertyOwner, Dictionary <Type, RdbTable> tablesCache)
{
RdbTable result = null;
if (propertyOwner == null)
{
propertyOwner = property.OwnerType;
}
if (!tablesCache.TryGetValue(propertyOwner, out result))
{
if (!propertyOwner.IsAbstract)
{
result = RdbTableFinder.TableFor(propertyOwner);
}
if (result == null)
{
ORMHelper.ThrowBasePropertyNotMappedException(property.Name, propertyOwner);
}
tablesCache.Add(propertyOwner, result);
}
return(result);
}
protected override void UpdateRedundancy(Entity entity, ConcreteProperty redundancy, object newValue, IList <ConcreteProperty> refPathes, object lastRefId)
{
/*********************** 代码块解释 *********************************
*
* 假定场景是：
* refPathes: D(CRef,AName) -> C(BRef) -> B(ARef)，
* lastRefId: AId。（B.ARef 是最后一个引用属性）
* 则对应生成的 SQL 是：
* update D set AName = @AName where CId in (
* select id from C where BId in (
* select id from B where AId = @AId
* )
* )
* 如果 B、C 表也有冗余属性，对应的 SQL 则是：
* update B Set AName = @AName where AId = @BId
* update C set AName = @AName where BId in (
* select id from B where AId = @AId
* )
*
**********************************************************************/
//准备所有用到的 DbTable
var table = RdbTableFinder.TableFor(redundancy.Owner);
var refTables = new RefPropertyTable[refPathes.Count];
for (int i = 0, c = refPathes.Count; i < c; i++)
{
var refProperty = refPathes[i];
var refTable = RdbTableFinder.TableFor(refProperty.Owner);
if (refTable == null)
{
ORMHelper.ThrowBasePropertyNotMappedException(refProperty.Name, refProperty.Owner);
}
refTables[i] = new RefPropertyTable
{
RefProperty = refProperty,
OwnerTable = refTable
};
}
var sql = new ConditionalSql();
//SQL: UPDATE D SET AName = {0} WHERE
sql.Append("UPDATE ").AppendQuoteName(table)
.Append(" SET ").AppendQuote(table, table.Translate(redundancy.Property))
.Append(" = ").AppendParameter(newValue).Append(" WHERE ");
int quoteNeeded = 0;
if (refTables.Length > 1)
{
//中间的都生成 Where XX in
var inWherePathes = refTables.Take(refTables.Length - 1).ToArray();
for (int i = 0; i < inWherePathes.Length; i++)
{
var inRef = inWherePathes[i];
//SQL: CId In (
sql.AppendQuote(table, inRef.OwnerTable.Translate(inRef.RefProperty.Property))
.Append(" IN (").AppendLine();
quoteNeeded++;
var nextRef = refTables[i + 1];
//SQL: SELECT Id FROM C WHERE
var nextRefOwnerTable = nextRef.OwnerTable;
sql.Append(" SELECT ").AppendQuote(nextRefOwnerTable, nextRefOwnerTable.PKColumn.Name)
.Append(" FROM ").AppendQuoteName(nextRefOwnerTable)
.Append(" WHERE ");
}
}
//最后一个，生成SQL: BId = {1}
var lastRef = refTables[refTables.Length - 1];
sql.AppendQuote(table, lastRef.OwnerTable.Translate(lastRef.RefProperty.Property))
.Append(" = ").AppendParameter(lastRefId);
while (quoteNeeded > 0)
{
sql.AppendLine(")");
quoteNeeded--;
}
//执行最终的 SQL 语句
using (var dba = _dataProvider.CreateDbAccesser())
{
dba.ExecuteText(sql, sql.Parameters);
}
}