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Posts: 409 / Nickname: bv / Registered: January 17, 2002 4:28 PM
Two-Way Data Binding in Flex 4
July 28, 2009 9:00 PM
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Data binding is among the most common UI programming tasks. Although the open-source Flex framework has supported data binding since its inception, the latest Flex 4 SDK adds two-way data binding as well. This tutorial illustrates two-way data binding in Flex 4.
http://www.artima.com/articles/two_way_binding.html What do you think of the approach to data binding presented in the article? |
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Posts: 3 / Nickname: kenonartim / Registered: August 12, 2009 8:31 AM
Re: Two-Way Data Binding in Flex 4
August 12, 2009 1:41 PM
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Data [Binding] is evil 'magic' and should be avoided by anyone who can program a solution instead. I realize this needs to exist for the non-programmers, but anyone who has an alternative should use it (if you want to have scalable and maintainable code) --- this comment arises from bitter experience of debugging [Bindable].
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Posts: 12 / Nickname: ianr / Registered: April 20, 2007 6:37 AM
Re: Two-Way Data Binding in Flex 4
August 14, 2009 6:40 AM
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> Data [Binding] is evil 'magic' and should be avoided by
> anyone who can program a solution instead. I realize this > needs to exist for the non-programmers, but anyone who has > an alternative should use it (if you want to have scalable > and maintainable code) --- this comment arises from bitter > experience of debugging [Bindable]. I would be interested in hearing more about this. Data binding seems to be a key language feature for Flex - perhaps the single most important feature from a UI standpoint. What sorts of debugging issues have you seen with it? |
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Posts: 3 / Nickname: kenonartim / Registered: August 12, 2009 8:31 AM
Re: Two-Way Data Binding in Flex 4
August 17, 2009 11:00 AM
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I have several times debugged problems where a 'cascade' of [Bindable] was used --- one [Bindable] triggers another [Bindable] etc., the final bindables were used to control features of columns in an advanced data grid. If you trace [Binadble] through the debug player, you will see that it does a 'LOT' of work. With a complex enough situation the Flex runtime can take longer than the server timeout (30 minutes) to return.
I have many situation with complex usage of [Bindable] that do work, but there is a limit to how complex the usage can be. In the situations where I had problems, simply removing [Bindable] and explicitly setting values solved the problem. I find that often [Bindable] is simply used as the 'easiest way', which is fine in small applications, but in a large 'mission critical' application you can get into a very difficult to detect problem, which if the code is being maintained months after it was written or being maintained by someone other than the original coder can be problematic. |
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Posts: 1 / Nickname: romanb / Registered: February 14, 2008 7:18 AM
Re: Two-Way Data Binding in Flex 4
August 15, 2009 1:05 PM
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> Data [Binding] is evil 'magic' and should be avoided by
> anyone who can program a solution instead. I realize this > needs to exist for the non-programmers, but anyone who has > an alternative should use it (if you want to have scalable > and maintainable code) --- this comment arises from bitter > experience of debugging [Bindable]. I assume you're only referring to Flex here and not Data Binding in general because Data Binding in .NET 3.x / WPF is pretty good and a key feature. |
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Posts: 3 / Nickname: kenonartim / Registered: August 12, 2009 8:31 AM
Re: Two-Way Data Binding in Flex 4
August 17, 2009 10:50 AM
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Yes, I am only referring to Flex.
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Posts: 1 / Nickname: robrusher / Registered: August 18, 2009 2:18 AM
Re: Two-Way Data Binding in Flex 4
August 18, 2009 7:24 AM
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Having only glanced at binding in WPF, how is it any different?
It appears that both Flex and XAML provide binding as a short cut to coding repetitive methods that handle data changes. |
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Posts: 1 / Nickname: fredericc / Registered: October 5, 2009 3:56 AM
Re: Two-Way Data Binding in Flex 4
October 5, 2009 9:06 AM
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Hello,
I'm quite familiar with Eclise Data Binding framework: http://wiki.eclipse.org/index.php/JFace_Data_Binding but quite new to Flex. IMHO beside converters, a complete data binding framework requires the following features: - onChange validation - ability to track the validity status of multiple fields within a form to know if the whole form is valid or not. Can you give to hints if those feature are available in Flex 3 or will be available in Flex 4 ? |
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Posts: 2 / Nickname: ljamese / Registered: August 6, 2010 3:46 PM
Re: Two-Way Data Binding in Flex 4
August 6, 2010 8:53 PM
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Is this supposed to work for binding between AS and MXML objects? For example, I have an AS object like this:
public class Foo { [Bindable] public var bar:String; } and an MXML class like this (abbreviated): <s:Group...> <s:TextInput id="someId"/> </s:Group> An instance of foo is provided to the MXML component via a code-behind page. I have tried binding foo.bar to someId.text in various ways, and it doesn't seem to work exactly. Meaning that if I change foo.bar then someId.text will change, but the reverse doesn't work. I've tried binding with: <fx:Binding source="foo.bar" destination="someId.text" twoWay="true"/> no workie, and: <s:TextInput id="someId" text="@{foo.bar}"/> still no workie. Any ideas? |
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Posts: 2 / Nickname: ljamese / Registered: August 6, 2010 3:46 PM
Re: Two-Way Data Binding in Flex 4
August 6, 2010 8:56 PM
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Bad form to reply to my own post, I know, but I also need to say that the compiler spits out a warning that "data binding will not be able to detect assignments to 'someId'.". What gives?
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