EOPopUpAssociation

Inherits from:

EOAssociation : EODelayedObserver (EOControl) : NSObject

Conforms to:

NSCoding

(EOAssociation)

EOObserving (EODelayedObserver)

NSObject (NSObject)

Declared in:

EOInterface/EOPopUpAssociation.h

Class Description

An EOPopUpAssociation object displays an attribute or to-one relationship value in an NSPopUpButton (Application Kit).

The items in the NSPopUpButton can be entered manually, or for a relationship, constructed dynamically from values supplied by the destination entity's EODisplayGroup. The value displayed by the NSPopUpButton can be bound by one of three aspects: selectedTitle, which is useful for values representable as strings; selectedTag, for integer values; and selectedObject, for the destination object of a relationship.

Examples

There are several basic ways to configure a combo box and it's association. They are described below.

Selecting a String from a Static List

Suppose you have a Movie display group and you want to provide a pop-up list for setting the rating from a static list of strings. In this example, a Movie object's rating is a string property rather than a relationship to a Rating object. To do this, in Interface Builder, type the list of ratings into the pop-up list. Control-drag a connection from the pop-up list to the Movie display group. Choose EOPopUpAssociation in the Connections inspector, and bind the selectedTitle aspect to the "rating" key. With this configuration, if an object's string attribute value isn't in the pop-up list, it's temporarily added while the object is selected.

Selecting a String from a Dynamic List

This example is similar to the previous one, except in this example, a Movie object's rating is chosen from strings in a Rating database table. There's a Rating EODisplayGroup that fetches the ratings into Rating objects, and the pop-up list is filled from the "ratingString" property of the rating display group's Rating objects. To do this, in Interface Builder, control-drag a connection from the pop-up list to the Ratings display group. Choose EOPopUpAssociation in the Connections inspector, and bind the titles aspect to the "ratingString" key. Similarly, control-drag a connection from the pop-up list to the Movie display group. Again choose EOComboBoxAssociation in the Connections inspector, and bind the selectedTitle aspect to the "rating" key.

Selecting an Integer Tag from a Static List

Suppose you have a Customer enterprise object whose credit card type (Visa, MasterCard, and so on) is indicated by an integer tag. You want a user to be able to choose a customer's card type from a pop-up list. To do this, in Interface Builder, set the credit card names and tags for the pop-up list. Control-drag a connection from the pop-up list to the Customer display group. Choose EOPopUpAssociation in the Connections inspector, and bind the selectedTag aspect to the "cardType" key. You can also allow for a general "other" value by defining a special tag and setting it in the EOPopUpAssociation using setTagValueForOther:. Credit card tags from the database not matching any in the pop-up list are then displayed as the "other" value. (It would also make sense to disable the pop-up list in this case, to avoid writing the meaningless tag back to the database.)

Selecting the Destination of a To-One Relationship

Suppose you have a list of employees and want to assign each employee a department. In terms of the object model, you want to assign a Department object as the destination of an Employee object's department relationship. To do this, in Interface Builder, control-drag a connection from the pop-up list to a Department display group. Choose EOComboBoxAssociation in the Connections inspector, and bind the titles aspect to the "name" key. Similarly, control-drag a connection from the pop-up list to the Employee display group. Again choose EOComboBoxAssociation in the Connections inspector, and bind the selectedObject to the "department" key. This fills the pop-up list with the names of departments, and causes the name of the selected Employee's Department to be selected in the pop-up list.

Instance Methods

setTagValueForOther:

- (void)setTagValueForOther:(int)tag

tagValueForOther

- (int)tagValueForOther