/// <summary>
/// 查询数据
/// </summary>
/// <typeparam name="T">返回实体class</typeparam>
/// <param name="db">IDatabase</param>
/// <param name="sql">sql 语句，参数用@前缀，自动识别数据库类型</param>
/// <param name="obj">参数：class or Dictionary<string, object>，class属性 or key必须与参数名称一致</param>
/// <returns>实体 list</returns>
public static List <T> Query <T>(this IDatabase db, string sql, object obj = null)
{
var list = new List <T>();
var t = typeof(T);
if (t.IsArray || t.IsAbstract)
{
return(list);
}
IReaderToModel ic = null;
bool isvalue = false;
if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable <>))
{
var gt = t.GetGenericArguments()[0];
if (gt.IsPrimitive && gt.IsValueType)
{
isvalue = true;
}
}
if (!isvalue && (t == typeof(string) || t.IsPrimitive && t.IsValueType))
{
isvalue = true;
}
if (!isvalue && t.IsClass)
{
ic = GetReaderToModel(t);
}
db.ClearParameters();
AddParam(db, sql, obj);
using (var reader = db.ExecuteReader())
{
while (reader.Read())
{
object o = default(T);
if (isvalue)
{
var v = reader.GetValue(0);
o = ChangeType(v, t) ?? default(T);
}
else if (ic != null)
{
o = ic.To(reader);
}
list.Add((T)o);
}
}
return(list);
}
private static IReaderToModel GetReaderToModel(Type t)
{
IReaderToModel ic = null;
Type convertType = null;
if (!cacheDic.TryGetValue(t, out convertType))
{
if (convertType == null)
{
convertType = CreateReaderToModelType(t);
if (convertType != null && !cacheDic.ContainsKey(t))
{
cacheDic[t] = convertType;
}
}
}
if (convertType != null)
{
ic = Activator.CreateInstance(convertType) as IReaderToModel;
}
return(ic);
}
