Re: [Pharo-users] dependent magritte descriptions

Dec. 6, 2017


      Am 06.12.17 um 11:34 schrieb Peter UhnÃ¡k:
...
Hi,
I'm trying to get dependent magritte descriptions, but it seems like this
is not something that can be done in the descriptions:
Imagine a class Contact with "city" and "country" descriptions.
I would like to populate the city description based on the currently
selected country
~~~~~~~~~~~~~~~~~~~~~~
descriptionCountry
<magritteDescription>
^ MASingleOptionDescription new
accessor: #country;
label: 'Country';
options: self countries;
yourself
descriptionCity
<magritteDescription>
^ MASingleOptionDescription new
accessor: #city;
label: 'City';
options: (self citiesInCountry: self country);
yourself
~~~~~~~~~~~~~~~~~~~~~~
The problem with this approach is that both descriptions are in the same
form, so I need to update the cities list even before the country is saved
back into the object.
Is this possible in magritte?
I had the same wish and came up with the following solution:

--- It will calculate the options with a block instead of an already
given collection.

--- It will recalculate (aka "not cache") the options if you hit the
"Save" button on the magritte form.

--- It will NOT recalculate the options on the fly when the other
dropdown box has been selected. This probably could be done with some
ajax stuff or a forced HTTP form send.

--- I use my own subclasses for magritte options, for example:

MASingleOptionDescription subclass: #ALMaSingleModelOptionDescription
	uses: TALMagritteOptionDescription
	instanceVariableNames: ''
	classVariableNames: ''
	package: 'Albus-Magritte'

--- See attached fileout of the Trait TALMagritteOptionDescription.

--- You can then describe an option as follows:

descriptionYourAttribute
	<magritteDescription>
	^ALMaSingleModelOptionDescription new
		accessor: #yourAccessor;
		optionsBlock: ["stuff to calculate your collection"];
		label: 'Your label';
		yourself


Cheers, Andreas


-- 
Andreas Brodbeck
www.mindclue.ch