Re: [Cppcms-users] url mapper

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Hi!

Thanks for your detailled answer!

The problems with the plugin and localization are now resolved, too.

Artyom Beilis wrote:
>>> my_stream.imbue(context().locale());
>>
>>That is working.
>>
>>I was asking myself how the booster::locale::translate is working within
>>plugins. In the main program translate() is working, but not in the
>>plugins. I did not called std::locale::global(gen(""));
>>
> 
> See:
> 
> stream << booster::locale::translate("foo")
> 
> Works because actual translation is postponed to the
> stage were the data is written to the stream and rendered withing it.
> 
> booster::locale::translate-> booster::locale::message + std::ostream's
> locale gives translation.
> 
> So if you want to use locale for your plugin you need to have some locale
> context. It can be done by
> 
> std::string translated = app.translate("foo");
> 
> or use locale explicitly as:
> 
> std::locale loc = app.context().locale();
> std::string translated = booster::locale::translate("foo").str(loc);
> 
> 
> or
> 
> std::locale loc = app.context().locale();
> std::string translated = booster::locale::gettext("foo",loc);
> 
> 
> Of course if your application uses only one language globally
> you can just set std::locale::global.

Thanks, I think we now have every option available.
I found a method for every problem!

>>But if it does not work well - see problem below - I may change to use
>>render() template. I do not understand the "With the command render"
>>example: In std::string  main_html(cppcms::applicatin *app) the plugin
>>still renders to a buffer and returs the string, so what is the
>>difference?
>>
> 
> It was just an example
> 
> However, if you call <% render ... %> from the view it renders to the
> output stream without intermediate buffers.

My plugin has a print(ostream& ) function and the print() is wrapped in a 
cppcms::filters::streamable main which is printed by <%= main | raw %>.
There should also be no intermediate buffer, or?

>>E.g. I have the following code:
> 
>>
>>17     void My_plugin::do(std::ostream & buf, cppcms::application & app)
>>18     {
>>19         if(app.request().request_method()=="POST")
>>20         {
>>21             m_main.m_form.load(app.context());
>>22             m_main.m_form.validate();
>>23             ::std::cout << "x is: " << m_main.m_form.x.value() <<
>>std::endl;
>>24             m_main.m_form.clear();
>>25         }
>>26
>>27         app.render("plugin_skin","main_html",buf,m_main);
>>28     }
>>
>>Then I get following exception:
>>2012-03-06 09:52:08; cppcms, error: Caught exception [Value was not
>>loaded] 0x40566414: booster::stack_trace::trace(void**, int) + 0x24 in
>>/usr/lib/libbooster.so.0
>>0x4015fe9b: cppcms::widgets::base_text::value() + 0xcb in
>>/usr/lib/libcppcms.so.1
>>0x43132180: My_plugin::do(std::ostream&, cppcms::application&) in line 23
>>
> 
> I think you had not added m_form.x to m_form  (using m_form.add(x));
> so when you access x.value() it appears not to be loaded when you
> call load(app.context());

You are completely right!
Thanks a lot!
I suggest to change the text "Value was not loaded" to something like "The 
value or the parent was not loaded. Check the hierarchy." ;)

>> Is there some explanation how this works if multiple applications are
>> mounted at the same root?
> 
> The behavior is undefined for `cppcms::application_pool`

Mmmh, but exactly this happens when you use the file server?
It is also mounted at "".

> Generally the first one will be selected, but non necessary, it
> may be changed in future. So you should provide mutually
> exclusive mount points.

I do not have that situation within my own framework.

> The dispatching and matching withing application (url_dispatched) is done
> according to the order of adding them to url_dispatcher.

Ok, good to know.

>>> Because when you map sub-application and refer to it
>>> you automatically referred to the default URL
>>> of the sub-application - empty one "empty key"
>>
>>Sorry, I do not understand this statement.
>>
> 
> First of all take a look on this tutorial carefully.
> 
> http://cppcms.com/wikipp/en/page/cppcms_1x_tut_hierarchy
> 
> 
> 
>>There are some examples for mapper and dispatcher, but I can't find
>>anything related to how the url() call works.
>>Doxygen just says: "Map url-key key to actual URL, without parameters"
> 
>>What does url("gui") does?
>>
> 
> application::url() and <% url ... %> is a family of functions with
> variable number of parameters.

How does the <% url ... %> using syntax work?

Why does <% url "/blog/post" using slug %> resolves to 
"/myblog/Hi%20%3cyou%3e/" 
(see http://cppcms.com/wikipp/en/page/cppcms_1x_templates_comm#URL.Mapping)

I would rather expect /blog/post/Hi%20%3cyou%3e/?

Both
<% url "/gui/system" %>
<% url "system" %>
work without problem, but I could not figure out how to resolve a variable 
containing "system"?

E.g. <% url "/gui/" using menu_element.m_href %> does not work?

> when you call url("foo") it looks for the object named "foo"
> 
> If it is actual function (not sub application) it provides a url
> 
> if it is subapplication it tries to dispatch the "" key.

Ok, I think I understand the approach now much better.

I still can't figure out the details between:
url("")
url(".")
url("/")

while the first two seem to be equivalent, url("/") seems to link to the 
same url where the request() came from?
e.g. when I request http://localhost:10000/gui/wrong_url
url("/") resolves to http://localhost:10000/gui/wrong_url
but url("") and url(".") resolves to ttp://localhost:10000/gui

When I use
dispatcher().assign("", &GUI::show_error_page, this);
mapper().assign("/"); // changed here instead of ""

the urls resolve to:
url("/") -> http://localhost:10000/gui/wrong_url
url(".") -> http://localhost:10000/gui/
url("") -> http://localhost:10000/gui/

So url(".") with assign("/") seems to be what I want ;)

> See, applications are generated in the hierary, so
> 
> For given application: foo, sub application bar and bar's method baz
> 
> url("/foo/bar/baz") would map to the "baz"'s url.
> 
> url("/foo/bar") would map to default (empty) url of baz application.
> 
> You can have parameters as well for example
> 
> // withing bar
> 
> mapper().assign("baz","/baz");
> mapper().assign("baz","/baz/{1}");
> mapper().assign("baz","/baz/{1}/{2}");
> 
> Then you can call:
> 
> url("/foo/bar/baz") -> something/baz
> url("/foo/bar/baz",20) -> something/baz/20
> url("/foo/bar/baz","x","y") -> something/baz/x/y

Thanks, I think I do not need parameters, because I prefer to have 
user/browser specific language and not by url.

>>Can I use mapper().set_value?
>>
>>
> 
> set_value should be used for some horizontal parameters
> like for example language when you want to change the URL
> independently from, the hierary.
> 
> mapper().set_value("lang","en")
> url("/foo/bar") -> en.wiki.org/foo/bar
> url("/baz") -> en.wiki.org/baz
> 
> mapper().set_value("lang","he")
> url("/foo/bar") -> he.wiki.org/foo/bar
> url("/baz") -> he.wiki.org/baz

Ok, thank you!

>>I think copy&paste of how wikipp does + explanation would help, because
>>the
> 
>>redirecting + url resolving there is what most users want anyway.
>>
> 
> Actually, wikipp was written before URL-mapper existed and I had
> no time to update it. Take a look rather on the cppcms's blog
> it uses url mapper fully.

Ok, so I think the examples you gave in this mail are perfect!

> P.S.: URL Mapper/Dispatcher is actually not-so simple and powerful part
> I need to write a better tutorial.

Yeah, they are powerful, I like them :-)

best regards
Markus