[Seaside] Accepting input from parent & child components

jtuchel at objektfabrik.de jtuchel at objektfabrik.de
Wed Sep 9 11:11:48 UTC 2015


in addition to all the good advice Otto has given you already, I'd like 
to point you to a few additional ideas/thoughts that might help.

First of all, the web browser has no idea about the structure of your 
Seaside Components, it only receives a Tree of DOM elements it acts 
upon. This may be obvious, but it is important to remember every time 
you need to find out what's wrong in cases like yours.

Since you are on GNU, I guess debugging is a bit harder than on most 
other Smalltalk environments. But even if I am wrong, you should take a 
deep look at the debugging/developer tools of your Web browser. You can 
take a deeper look at your DOM, but you can also get traces of the HTTP 
requests/responses that travel back and forth between your Seaside 
Server and the Browser. So if you expect the input of an input element 
to be sent to the server, it is always a good idea to have a look at the 
POST request that gets sent by the browser. Say you entered "Hello" into 
a textinput element, see if it's being sent to the server before you do 
anything else. Just open the dev tools and inspect the POST request. You 
shoudl finde something like "&56=Hello" in your POST request. If not, 
the problem is very likely in your rendering code: your input field is 
not inside of the form tag, most likely. Then you should take a closer 
look at the DOM and your rendering code once you see what's wrong. An 
interesting mosaic piece may be that the "56" in the POST request is the 
content of the "name" attribute of the html tag (something linke <input 
type="text" name="56">) that was generated by Seaside. 56 in this 
example is also the key for the Callback Block in the Callbacks 
Dictionary on the server side.

If the POST request contains your field and its contents but the setter 
method on the server side is not called (Breakpoint or self halt), then 
your wiring of the input field is wrong in your renderContentOn: Maybe a 
typo in the callback block, or, if you used #on:of:, in the attribute 
name. Note that Seaside simply ignores keys that it cannot find in the 

Hope these thoughts help you understand a little more about your situation.

Finally I'd like to ask you to let us know what your problem was and how 
you fixed it. We need more of these "what went wrong and how could it be 
solved" descriptions. One example: If you forget a "super initialize" in 
a WAComponent subclass, you end up with a very strange error message 
that doesn't really help (don't remember exactly, sorry! I think I 
blogged about it a few years ago...) during rendering. The solution is 
just to add the super call, but finding it takes a lot of time.



Am 08.09.15 um 01:39 schrieb Mark Bratcher:
> Hello
> I have a WAComponent that displays some input fields, and it renders a 
> child component that displays additional, related input fields. For 
> example, if I'm having the user edit an invoice, there are general 
> items on the invoice (like special terms of payment, etc) and then 
> there are invoice line items, which are rendered and input via a 
> subcomponent.
> The parent input fields and subcomponent input fields are within the 
> same html `form`. However, when I click the submit button (done at the 
> parent level), only the input items rendered by the parent are 
> recognized. Any inputs provided by the user through the embedded, 
> rendered subcomponent are ignored.
> I bought and have been reading Dynamic Web Development With Seaside, 
> but it does not address this case.
> Is it possible to do what I'm attempting to do?
> Thank you
> Mark
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> seaside at lists.squeakfoundation.org
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Objektfabrik Joachim Tuchel          mailto:jtuchel at objektfabrik.de
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D-71640 Ludwigsburg                  http://joachimtuchel.wordpress.com
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