What's in a name? Data Bindings are called this way because they bind various data to each other. When you bind something in the real world (such as a package to the roof of a car) you actually tie it tightly. That's the core meaning here -- tying something tightly. With data bindings, you tie data tightly to other data.
For example, you can have a textbox in a dialog which is grayed-out. You can't write anything in it. This textbox can have a checkbox next to it, saying something like "Enable this setting?". Once the checkbox is checked, the textbox magically becomes white (enabled) and you can write in it. This is done via data bindings -- the value of the checkbox (Enabled or Disabled) is bound to the state of the textbox (Enabled or Disabled). AggreGate data bindings let you do such nice interface tricks using widgets - this is just one example of their power.
Every binding consists of two parts:
reference = expression
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If you're not sure what a reference or an expression is, you really should check out the previous two articles. Without a thorough understanding of references and expressions, bindings won't make much sense. |
reference defines the binding target. This is where the result of the expression will be written to, once the binding is processed. Depending to the processing environment, reference may refer to a Data Table cell, property of User Interface component etc. See references chapter for more info on references.
expression is an AggreGate expression that defines the value to be written to the binding target when the binding is processed.
See the following chapters for more info on using bindings: