cppcms-users

[Cppcms-users] app().session().erase() doesn't work or not permitted?

[<ele...@ex...>]

I've just added a simple message to be displayed on website.

ie.
session().set("msg", "User Updated");

And then in my content class I have a get_message() function which gets
called from inside a template.

get_message() does simple -

string msg;

if (app().session().is_set("msg")) {
    msg = app().session().get("msg"); //works
    app().session().erase("msg"); // doesn't work
}

return msg; // always returns text because it never gets erased

Is modifying a session via app().session() not permitted or is it a bug?
Erasing the key from controller works fine.

Another question - why is session_interface::get() not const?

Cheers,
Petr

Re: [Cppcms-users] app().session().erase() doesn't work or not permitted?

[Artyom B. <art...@ya...>]

> 

> string msg;
> 
> if (app().session().is_set("msg")) {
>     msg = app().session().get("msg"); //works
>     app().session().erase("msg"); // doesn't work
> }
> 
> return msg; // always returns text because it never gets erased
> 
> Is modifying a session via app().session() not permitted or is it a bug?
> Erasing the key from controller works fine.
> 


You can't do changes in session **after** writing **any** output
(including just accessing to response().out() without actual I/O)

> Another question - why is session_interface::get() not const?
> 

Because it allows to use lazy evaluation, caching etc... You will not find many
const member functions in general withing CppCMS for this reason.

> Cheers,
> Petr
>

Artyom

Re: [Cppcms-users] app().session().erase() doesn't work or not permitted?

[<ele...@ex...>]

 > You can't do changes in session **after** writing **any** output
> (including just accessing to response().out() without actual I/O)
>

I figured that out while reading the header file for session_interface. Do
you think it may be handy to include that in the doxygen API
documentation? Or maybe have it spit out a warning?

> Because it allows to use lazy evaluation, caching etc... You will not find
> many

Thanks!
Petr

Re: [Cppcms-users] app().session().erase() doesn't work or not permitted?

[Artyom B. <art...@ya...>]

>________________________________

> From: "ele...@ex..." <ele...@ex...>
>To: Artyom Beilis <art...@ya...>; cpp...@li... 
>Sent: Sunday, April 22, 2012 5:05 AM
>Subject: Re: [Cppcms-users] app().session().erase() doesn't work or not permitted?
> 
>> You can't do changes in session **after** writing **any** output
>> (including just accessing to response().out() without actual I/O)
>>
>
>I figured that out while reading the header file for session_interface. Do
>you think it may be handy to include that in the doxygen API
>documentation? Or maybe have it spit out a warning?
>


It is in Doxygen API:

http://cppcms.com/cppcms_ref/latest/classcppcms_1_1session__interface.html#details


Quoting:

    All changes in session should be done before headers are written
   to the output (before requesting an output stream from http::response object)

Also It seems that it should be more "highlighted" there.


Because it is quite FAQ there.

Artyom

Re: [Cppcms-users] app().session().erase() doesn't work or not permitted?

[<ele...@ex...>]

> It is in Doxygen API:
>
> http://cppcms.com/cppcms_ref/latest/classcppcms_1_1session__interface.html#details


My bad, i should have read it more thoroughly. Highlighting it would be
great too.

Cheers,
Petr