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Common WODisplayGroup Methods The WODisplayGroup performs all database accesses for your application. The more commonly used methods are listed below, sorted by the type of operation they perform. Displaying Results These methods give you access to database objects and allow you to display them. allObjects All of the records to be displayed. For example, if your application has a query that results in one hundred records being fetched but you have set up the display group to only display ten at a time, allObjects contains all one hundred records. displayedObjects The records actually being displayed. For example, if your application has a query that results in one hundred records being fetched but you have set up the display group to only display ten at a time, displayedObjects contains those ten records. selectedObjects The records in the current selection. selectedObject A single selected record. Usually, this returns the first record in the selectedObjects array. Managing Batches These methods control the grouping of records into manageable batches to display. (You set the batch size on the WODisplayGroup options panel.) displayPreviousBatch Select the previously-displayed batch of records and then reloads the page. displayNextBatch Selects the next batch of records and then reloads the page. batchCount The number of batches to display. For example, if you're fetching two hundred records and the batch size is ten, batchCount returns twenty (twenty batches of ten records each). batchIndex The number of the batch currently displayed, where 1 is the first batch displayed. For example, if the batch size is ten records and displayedObjects is showing records 11 through 20, the batchIndex is 2. Querying These methods are used in applications that perform queries. executeQuery Builds a qualifier using inputObjectForQualifier and the pattern matching you set on the display group options panel, and then fetches the records that match that qualifier. The qualifier is not preserved. inputObjectForQualifier Returns an entity object that is used to create the qualifier. For example, if you wanted the application to search on movie titles, you would bind a text field to inputObjectForQualifier.title. (title comes from the entity that created the WODisplayGroup.) secondObjectForQualifier Used for from-to queries to specify the "to" value. This method must use the same property as inputObjectForQualifier. For example, if you wanted to query all movies released between two dates, you would bind the first field inputObjectForQualifier.dateReleased and the second field to secondObjectForQualifier.dateReleased. The resulting qualifier would fetch all movies release after the date specified in inputObjectForQualifier but before the date specified in secondObjectForQualifier. Modifying the Database These methods modify the database. insert Adds a new empty record. You should provide a dictionary containing default values for the record and use the setInsertedObjectDefaultValues: to specify that the WODisplayGroup should use that dictionary to create all new values. For example, these statements ensure that all new records contain a value for movie title: [dictionary setObject:@"New title"] forKey:@"title"]; [movies setInsertedObjectDefaultValues:dictionary]; delete Deletes the selected records. If you're modifying a database, you must explicitly save the changes. Write a method that uses the session's EOEditingContext to save the changes. For example: [self.session.defaultEditingContext saveChanges]; See the EOEditingContext class description in the Enterprise Objects Framework Reference.

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