如何在Entity Framework Core 2.0中从DbDataReader转换为Task <IEnumerable <TEntity >>？

Question

我通过以下方式在EF Core 2.0中调用存储过程.

private async Task<IEnumerable<TEntity>> InvokeStoredProcedureAsync(string entityName)
{
    var storedProcedureName = string.Format(CultureInfo.InvariantCulture, "sp_{0}BulkSelect", entityName);
    dynamic temp;
    using (MyDbContext MyDbContext = new MyDbContext(_options))
    {
        MyDbContext.Database.OpenConnection();
        DbCommand cmd = MyDbContext.Database.GetDbConnection().CreateCommand();
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = storedProcedureName;

        using (var reader = cmd.ExecuteReader())
        {
           temp = reader.Cast<Task<IEnumerable<TEntity>>>();
        }
    }

    return await temp;
}

我需要转换DbDataReader为Task<IEnumerable<TEntity>>.

但是在尝试扩展temp变量以查看其值时,我收到此错误.

读取器关闭时无效尝试调用FieldCount.

请参阅随附的屏幕截图.

Answer 1

除了明显的异步代码问题,您无法DbDataReader通过简单调用实现类Cast.如果可能的话,就不需要像Dapper和类似的微型ORM.

EF Core目前没有公开这样做的公开方式.但如果TEntity是模型实体类,您可以简单地使用该FromSql方法:

private async Task<IEnumerable<TEntity>> InvokeStoredProcedureAsync(string entityName)
{
    var storedProcedureName = string.Format(CultureInfo.InvariantCulture, "sp_{0}BulkSelect", entityName);
    using (var db = new MyDbContext(_options))
    {
        var result = await db.Set<TEntity>().FromSql(storedProcedureName).ToListAsync();
        return result;
    }
}

确保SP按TEntity映射返回所有预期的列.