[web2py] Re: How capable is the ajax function in web2py.js?

2012-06-26 Thread stefaan 



 Now I realize that in order to interact with the table, which is managed 
 by pyjamas, for example to select a certain row, I need to define a complex 
 JSONRPCs interface (select row, un-select, paginate to next page, previous 
 page, last page, page number, ...), passing back and forth parameters and 
 results between web2py and pyjamas. This looks quite complex.


One thing that can reduce playing ping-pong with the server (and therefore 
also reduce complexity + enhance performance): 
think about when you really need to contact the server, and accumulate 
other changes in the client until you actually contact it.

In an application I'm currently prototyping, I allow a user to do lots of 
manipulations on a table (selecting rows, filtering visible data, sorting 
columns, ...) purely in the client.
When the user selects a row, I dynamically change its css style so it looks 
differently on screen. No need to contact the server for that. 
Inside the client (pyjamas) I maintain a data structure in response to the 
user interactions that encodes updates to the current state of the 
application 
(think: a list of currently selected rows).

Only when absolutely needed, the new state of the application is sent back 
to the server (i.e. to web2py using JSONRPC) and processed, or new data is 
requested from the server.

As explained by Anthony (most of the effort will be on the client side), 
I think using Ajax/JQuery directly won't make things fundamentally easier 
(on the contrary: unless you find a pre-made component that already does 
what you want you will now have to write your client side stuff in 
javascript instead of python, which - depending on your background - may 
sound scary).

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[web2py] Re: How capable is the ajax function in web2py.js?

2012-06-26 Thread Daniel Gonzalez 
Thanks for both your comments, they are good food for thought.

My experience with Javascript is very limited and I want to avoid it as 
much as possible. That is why I have considered - and tried - pyjamas 
(which has been working very well for me: very easy to use, and up to now 
very robust). I have some worries:

   1. This approach means I must keep coding, and integrating, two 
   technologies: web2py and pyjamas. It is still way better than having to 
   code in javascript.
   2. One thing that worries me about implementing all this logic 
   client-side is that a big chunk of my code will be autogenerated 
   javascript. That means, if I run into trouble, I guess it will be very 
   difficult to solve any problems I may have.
   3. And this a side issue, but I need to mention it nevertheless: I am 
   having a hard time integrating the CSS from pyjamas and web2py. Since some 
   styles from web2py (table, td, ...) override my styles, suddenly all my 
   pyjamas components are looking very bad. This is a very painful problem, 
   which I do not know how to solve. Do you have any suggestions on how to 
   debug CSS issues? I am limited to Chrome inspector basically.

So what I was aiming at now is to use as little client side logic as 
possible: just perform some AJAX calls to get the data ready for 
presentation. Actually, I was even planning to do (for example) HTML table 
rendering on the server (I am considering 
markup.pyhttp://markup.sourceforge.net/ for 
that) and send it via AJAX to the client to be displayed. Basically, the 
server would be in charge of updating the html in the client. The same that 
web2py does with controllers/views/functions, but for dynamic content, 
which must be sent via AJAX.

I have not yet decided which approach to take. If you have experience in 
this scenario, your comments are welcome!

Thanks,
Daniel

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[web2py] Re: How capable is the ajax function in web2py.js?

2012-06-26 Thread Cliff Kachinske 
Daniel,

Do your table manipulation in Web2py using view helpers.

Example:
thead = THEAD(TR(TH(something'), TH('this'), TH('that'), TH('theother')))
tbody = TBODY()
for r in rows:
   tbody.append(TR(
 r.something, r.this, r.that, r.theother
  ))
return TABLE(thead, tbody)

There are other examples with even fewer lines of code in the manual at 
http://web2py.com/books/default/chapter/29/5#Built-in-helpers.

This is just how I like to do it.

On Tuesday, June 26, 2012 5:12:49 AM UTC-4, Daniel Gonzalez wrote:

 Thanks for both your comments, they are good food for thought.

 My experience with Javascript is very limited and I want to avoid it as 
 much as possible. That is why I have considered - and tried - pyjamas 
 (which has been working very well for me: very easy to use, and up to now 
 very robust). I have some worries:

1. This approach means I must keep coding, and integrating, two 
technologies: web2py and pyjamas. It is still way better than having to 
code in javascript.
2. One thing that worries me about implementing all this logic 
client-side is that a big chunk of my code will be autogenerated 
javascript. That means, if I run into trouble, I guess it will be very 
difficult to solve any problems I may have.
3. And this a side issue, but I need to mention it nevertheless: I am 
having a hard time integrating the CSS from pyjamas and web2py. Since some 
styles from web2py (table, td, ...) override my styles, suddenly all my 
pyjamas components are looking very bad. This is a very painful problem, 
which I do not know how to solve. Do you have any suggestions on how to 
debug CSS issues? I am limited to Chrome inspector basically.

 So what I was aiming at now is to use as little client side logic as 
 possible: just perform some AJAX calls to get the data ready for 
 presentation. Actually, I was even planning to do (for example) HTML table 
 rendering on the server (I am considering 
 markup.pyhttp://markup.sourceforge.net/ for 
 that) and send it via AJAX to the client to be displayed. Basically, the 
 server would be in charge of updating the html in the client. The same that 
 web2py does with controllers/views/functions, but for dynamic content, 
 which must be sent via AJAX.

 I have not yet decided which approach to take. If you have experience in 
 this scenario, your comments are welcome!

 Thanks,
 Daniel


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[web2py] Re: How capable is the ajax function in web2py.js?

2012-06-25 Thread Anthony 



1. I do not want to reload pages: everything needs to work smoothly as 
a desktop app. (of course, not all interactions with web2py, just the ones 
related to this one real-time component). I guess the right tool for this 
job would be the ajax function in web2py.ps. Is this tool able to 
handle complex data?

 The ajax() function is just a basic convenience function. It pulls values 
from input elements, posts them via Ajax using jQuery, and places the 
returned HTML in a specified target (or executes some returned Javascript). 
It relies on jQuery for the actual Ajax calls, so if you need to do 
anything more sophisticated, you can just use jQuery directly. You should 
be able to handle whatever Ajax you need.


1. the ajax events must not only be generated by the user, but also 
autonomously by the web browser. In pyjamas I am doing this with a Timer, 
which translates to some timer javascript events. Is this possible in 
web2py? Is there an example of a javascript timer triggering ajax requests 
in web2py?

 If you use a web2py Ajax component (which uses the web2py_component() JS 
function), in trunk there is now a timer option. Otherwise, you should be 
able to implement your own timer. Note, anything you can do with Ajax is 
technically possible with web2py -- web2py is a server-side framework and 
is happy to receive Ajax requests and return responses. Most of the effort 
will be on the client side -- for that, web2py provides some convenience 
methods, but you are free to use other third-party libraries or build your 
own JS/Ajax solution.

Anthony

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