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EORecursiveBrowserAssociation

Inherits from:
EOAssociation : EODelayedObserver (EOControl) : NSObject

Implements:
EOObserving (EODelayedObserver)

Package:
com.apple.yellow.eointerface

Class Description

An EORecursiveBrowserAssociation is the default association for use with a multi-column NSBrowser (Application Kit).

Note: This class doesn't exist in the com.apple.client.eointerface package.

EORecursiveBrowserAssociation manages hierarchical structures, such as a company's management chain-the first column is filled with top-level managers, the second column is filled with the employees who report directly to the selected top-level manager, and so on.

Usable With

NSBrowser (Application Kit)

Aspects
rootChildren	An array of objects with which to fill the browser's first column.
title	An attribute of objects to display in the browser's cells.
isLeaf	A boolean attribute of objects that determines whether the corresponding browser cell is a leaf (`true`) or a branch (`false`).
children	An NSArray attribute of the selected object, with which to fill the next column. This aspect is only used when the selected object is a branch (responds `false` to `isLeaf`).

Object Keys Taken
target	used to handle user click actions within the browser. The association sends the proper synchronization msg to the DG.
delegate	used to fill in the values of the browser

Example

Suppose you want to display a company's management structure in a browser. Start with a display group for Employee objects. Programmatically qualify this display group to fetch only the top-level management (the Employees with which to fill the browser's first column).

Drag a browser into a window. Be sure to set it to "Allow branch selection." Control-drag from the browser to your Employee display group. In the Interface Builder's Connections Inspector (EORecursiveBrowserAssociation-labeled EORecBrowser-is chosen by default), bind the rootChildren aspect to Employee's directReports relationship (a recursive, to-many relationship). Making this binding has the effect of:

Creating a new display group named "LastEmployeeColumn." More generally, the new display group has a name of the form, "Last NameOfFirstDisplayGroup Column."
Preconnecting the new display group to a data source.
Binding the EORecursiveBrowserAssociation's children aspect to the directReports relationship-the same relationship used for the rootChildren aspect.

Now bind the title and isLeaf aspects. (Note that if you try to bind these aspects before you bind the rootChildren aspect, you'll bypass work that the association can do for you automatically.) Control-drag from the browser to either of the display groups, and bind the association's title aspect to the fullName key and the isLeaf aspect to the isIndividualContributor key (a method that returns false if the Employee is a manager with direct reports). It doesn't matter what display group you make these bindings to, because the association expects rootChildren and children to reference the same kind of objects (have the same keys).

Now the association populates the browser's columns based on the selection in the previous column. You might want to create a master-detail association between the LastColumn display group and another display group. For example, the Employees application might display information about the employee selected in the browser's right-most column.

The rootChildren Aspect

When you bind an EORecursiveBrowserAssociation's rootChildren aspect, the association assumes that children will be bound to the same key. However, it's possible for you to bind these aspects to different keys. If you want to do this, you'll have to disconnect the children binding that the association creates automatically, and then rebind it to the key you want to use. Note that you only have this freedom with the first column. Subsequent columns must all use the same key to satisfy the children aspect.

Constructors

EORecursiveBrowserAssociation

public EORecursiveBrowserAssociation(Object aDisplayObject)

Creates a new EORecursiveBrowserAssociation to monitor and update the values in aDisplayObject, an NSBrowser (Application Kit).

You normally set up associations with the Interface Builder application, in which case you don't need to create them programmatically. However, if you do create them up programmatically, setting them up is a multi-step process. After creating an association, you must bind its aspects and establish its connections.

See Also: bindAspect (EOAssociation), establishConnection (EOAssociation)