I use this very bad code to partiallly hide the lack of the feature
namespace soci
{
template<typename T>
T get_integer_casted(const values& v, const std::string& field)
{
return static_cast<T>(v.get<int>(field));
}
}
2013/3/5 Pawel Aleksander Fedorynski <[email protected]>
>
> On Tue, Mar 5, 2013 at 12:18 PM, Nicolas Deroche <[email protected]>wrote:
>
>> Thanks for the reply,
>> I figured out casting from v.get<int> to C++'s unsigned long doesn't make
>> any data loss, as you said in your mail
>>
>> I'd like to point out the lack of this information on the documentation
>> on the website !
>>
>
> You are right, sorry about that!
>
>
>>
>> In the future, I hope this could change, and be able to use directly C++
>> types in the get<T> template function, or at least something less strict
>> like
>> - short (0 to 255); int (0 to 65K); long (0 to 4M); and long 64 for
>> greate values
>>
>
> I completely agree, there is no reason why v.get<short>(...) shouldn't
> work as long as the actual value is in the short's range, no matter what
> type it had in the database.
>
> Thanks,
>
> Aleksander
>
>
>> - bool's, and something else for other specific types.
>>
>> IMO, this could give some noob-friendly startup for the library !
>>
>> Thanks again,
>>
>> nico
>>
>>
>> 2013/3/5 Pawel Aleksander Fedorynski <[email protected]>
>>
>>>
>>>
>>> Hello Nico,
>>>
>>> Right now SOCI (or at least the MySQL backend) is very strict about the
>>> types when using the row interface. This is often inconvenient and we
>>> should probably change it. But for now the rules are:
>>>
>>> - All integer types smaller than INT are promoted to int, regardless
>>> whether the original type was signed or unsigned. So, e.g., if you select
>>> a value of type TINYINT UNSIGNED, you should retrieve it from the rowset
>>> using v.get<int>("id").
>>>
>>> - INT is retrieved as int: v.get<int>("id")
>>>
>>> - INT UNSIGNED is retrieved as (signed) long long: v.get<long
>>> long>("id"), although this will work too: v.get<unsigned>("id").
>>>
>>> - BIGINT is retrieved as long long.
>>>
>>> - BIGINT UNSIGNED is retrieved as unsigned long long.
>>>
>>> If you don't know the type that was selected form the database, you can
>>> use v.get_properties("id").get_data_type() to find out. It will be
>>> dt_unsigned_long_long for BIGINT UNSIGNED, dt_long_long for BIGINT and INT
>>> UNSIGNED, and dt_integer for all the smaller integral types.
>>>
>>> Unless I'm mistaken this problem only pertains to the row interface
>>> (dynamic binding), when you use static binding, i.e., into(n) this should
>>> be more forgiving with respect to types.
>>>
>>> Thanks,
>>>
>>> Aleksander
>>>
>>> On Tue, Mar 5, 2013 at 6:21 AM, Nicolas Deroche <[email protected]>wrote:
>>>
>>>>
>>>> Hello,
>>>>
>>>> I just started using SOCI, and I have one quick question about casting
>>>>
>>>> Consider this structure:
>>>> struct A
>>>> { unsigned long one; unsigned int two; unsigned short three; }
>>>>
>>>> In MySQL, the fields are defined like:
>>>> one : INT unsigned
>>>> two: SMALLINT unsigned
>>>> three: TINYINT unsigned
>>>>
>>>> How am I supposed to cast using the static templated function from_base
>>>> the SQL values into my structure?
>>>> static void from_base(values const & v, indicator /* ind */, A& s)
>>>> {
>>>> s.one = v.get<unsigned long>("id"); /// Throws std::bad_cast()
>>>> }
>>>>
>>>> Thanks,
>>>>
>>>> nico
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------------
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>>>> _______________________________________________
>>>> soci-users mailing list
>>>> [email protected]
>>>> https://lists.sourceforge.net/lists/listinfo/soci-users
>>>>
>>>
>>>
>>>
>>> ------------------------------------------------------------------------------
>>> Everyone hates slow websites. So do we.
>>> Make your web apps faster with AppDynamics
>>> Download AppDynamics Lite for free today:
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>>> _______________________________________________
>>> soci-users mailing list
>>> [email protected]
>>> https://lists.sourceforge.net/lists/listinfo/soci-users
>>>
>>>
>>
>>
>> ------------------------------------------------------------------------------
>> Everyone hates slow websites. So do we.
>> Make your web apps faster with AppDynamics
>> Download AppDynamics Lite for free today:
>> http://p.sf.net/sfu/appdyn_d2d_feb
>> _______________________________________________
>> soci-users mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/soci-users
>>
>>
>
>
> ------------------------------------------------------------------------------
> Everyone hates slow websites. So do we.
> Make your web apps faster with AppDynamics
> Download AppDynamics Lite for free today:
> http://p.sf.net/sfu/appdyn_d2d_feb
> _______________________________________________
> soci-users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/soci-users
>
>
------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
http://p.sf.net/sfu/appdyn_d2d_feb
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