cppcms-users

[Cppcms-users] working with http::context.

[augustin <aug...@ov...>]

Hello,

I've been trying to work with http::context but with no success.

I am working with forms. During the validation process, I want to set some 
messages to display to the user.

I have seen widgets::base_widget::error_message() but this is not what I need.

I want to:
1) be able to set errors for the *whole* form, not a specific widget.
2) be able to set various messages that are valid only within a specific 
context (http get/post request).

If I understand well, I cannot set those message within my cppcms::application 
namespace, since it is shared between all processes, regardless of user or 
sessions (?). Thus a message intended for one user might be displayed for 
another user.

I could use the user session, but a message intended for one page (form 
submission() might appear on another tab, as the user browses other pages 
within the site (race condition?).

It appeared to me that the http::context might be the best place to store 
temporary messages that I could retrieve and display at the end of the 
request.

But I have tried and failed. I am not too sure if it's possible and how to go 
about it. I have tried to add members to the context object. If it's possible 
to do so, I did it the wrong way.


Thanks,

Augustin.




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Re: [Cppcms-users] working with http::context.

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

> 
> I've been trying to work with http::context but with no  success.
> 
> I am working with forms. During the validation process, I want  to set some 
> messages to display to the user.
> 
> I have seen  widgets::base_widget::error_message() but this is not what I 
need.
> 
> I want  to:
> 1) be able to set errors for the *whole* form, not a specific  widget.
> 2) be able to set various messages that are valid only within a  specific 
> context (http get/post request).

If entry form fails validation you may just display any message you want
outside widgets system. i.e.

if(request().request_method()=="POST") {
   my_content.my_form.load(context());
   if(!my_content.my_form.validate()) {
      my_content.fail_flag = true;
   }
}


And in template system itself

<% if fail_flag %>
   <strong>FAILED</strong>
<% end %>
<form ... >
<% form as_p my_form %>
</form>


See example of forms. Also you can specify a number of reasons
and add some flag to form you are created.

> 
> If I understand well, I  cannot set those message within my cppcms::application 
>
> namespace, since it  is shared between all processes, regardless of user or 
> sessions (?). Thus a  message intended for one user might be displayed for 
> another user.
> 
> I  could use the user session, but a message intended for one page (form 
> submission() might appear on another tab, as the user browses other pages 
> within the site (race condition?).


I don't understand. What do you mean message? What do you mean shared?
What race condition?

> 
> It appeared to me that the  http::context might be the best place to store 
> temporary messages that I  could retrieve and display at the end of the 
> request.

No, http::context just preservers specific information for single
request/response. You can't change or alter it.

> 
> But I have  tried and failed. I am not too sure if it's possible and how to go 

> about it.  I have tried to add members to the context object. If it's possible 

> to do  so, I did it the wrong  way.

You can't and shouldn't derive from context.

Artyom


      

Re: [Cppcms-users] working with http::context.

[augustin <aug...@ov...>]

On Tuesday 24 August 2010 09:07:21 pm Artyom wrote:
> If entry form fails validation you may just display any message you want
> outside widgets system. i.e.
> 
> if(request().request_method()=="POST") {
>    my_content.my_form.load(context());
>    if(!my_content.my_form.validate()) {
>       my_content.fail_flag = true;
>    }
> }
> 
> And in template system itself
> 
> <% if fail_flag %>
>    <strong>FAILED</strong>
> <% end %>
> <form ... >
> <% form as_p my_form %>
> </form>
> 

Thank you, Artyom. 
That's not exactly what I wanted to do, but you put me back on the right 
track. 
I wanted to be able to add messages for the user from within 
my_content.my_form.validate().

What I did is create a struct to hold messages:

struct user_messages {
        std::list<std::string> messages;
};

I add this struct to my base_content and pass it by reference to 
my_content.my_form.validate() so that I can populate it with actual messages 
according to the validation process.
Then I can output it within the template using a foreach loop.

There may be better ways, but it works for now. When I have more experience, I 
might come up with a more elegant solution.



> See example of forms.

Yes, I had studied it closely. Your examples are very useful and I reproduced 
them to learn from them.

> Also you can specify a number of reasons
> and add some flag to form you are created.

I am not too sure what you are referring to, here.


> No, http::context just preservers specific information for single
> request/response. You can't change or alter it.

Ok. That was my mistake. I was trying to store temporary data (i.e. data 
related to the current request only) somewhere in http::context instead of 
putting it into my class derived from cppcms::base_content, as you suggested 
above.

Anyway, your reply was very useful, as usual, and I managed to do more or less 
what I wanted. Thank you.


Augustin.



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