public bool Select(object entity, params object[] outputProperties)
{
object entityType = MappingProvider.GetEntityTypeByInstance(entity);
List <string> outputs = Util.CollectNames(outputProperties);
QueryExpression queryExpression = new QueryExpression();
queryExpression.EntityType = entityType;
if (outputProperties == null || outputProperties.Length == 0)
{
ITable table = MappingProvider.GetTable(entityType);
queryExpression.Selects.Add(table.NonPrimaryKeyProperties);
}
else
{
queryExpression.Selects.Add(outputs);
}
queryExpression.Wheres = CreateConditionByKeyColumn(entity);
if (queryExpression.Selects.Count <= 0)
{
return(Exists(entity));
}
SelectionResult result = SqlProvider.SelectCollection(this, MappingProvider, null, queryExpression);
bool hasResult = result.DataReader.Read();
if (hasResult)
{
ObjectAccessor.Fill(SqlProvider, MappingProvider, result.DataReader, entity, result.ObjectFiller);
}
result.DataReader.Close();
return(hasResult);
}
/// <summary>
/// Internal Extendable method: 创建实体对象
/// </summary>
/// <param name="objectAccessor">实体对象访问器</param>
/// <param name="tableMapper">Table元数据解析器</param>
/// <param name="reader">数据流</param>
/// <param name="columnNames">查询结果列的数组</param>
/// <returns>实体对象</returns>
internal static object CreateEntity(this ObjectAccessor objectAccessor, ITableMapper tableMapper, IDataReader reader, string[] columnNames)
{
//创建对象
object entity = objectAccessor.CreateInstance();
//读取DataReader当前行,为entity各个属性赋值
objectAccessor.Fill(tableMapper.GetColumnMappers(), reader, columnNames, entity);
//返回对象
return(entity);
}
public int SelectCollection(IList list, IQueryExpression queryExpression)
{
if (queryExpression.EntityType == null)
{
throw new InvalidOperationException("queryExpression.EntityType属性不允许空");
}
SelectionResult result = SqlProvider.SelectCollection(this, MappingProvider, null, queryExpression);
int oldCount = list.Count;
while (result.DataReader.Read())
{
object entity = ObjectAccessor.CreateInstance(queryExpression.EntityType);
ObjectAccessor.Fill(SqlProvider, MappingProvider, result.DataReader, entity, result.ObjectFiller);
list.Add(entity);
}
result.DataReader.Close();
int i = queryExpression.ReturnMatchedCount ? result.TotalMatchedCount : list.Count - oldCount;
return(i);
}
