Note: Using this pattern with languages that do not use alphabets will be costly. There are ways to logically group characters, but the grouping mechanism must be agreed on for each affected language and the code to translate the pattern must be provided by the team that uses it.

Alphabet filters are a row of linked letters on the secondary toolbar of a table. They are a special case of toolbar filters.

The set of alphabet filters is bound to a column in the table. That column must correspond to a primary identifier for the object represented by the table, such as name, title, or code. The column must be visible by default.

Selecting a letter adds an <attribute> Starts With condition to the query whose result set is displayed in the table. Selecting a letter highlights the selected letter and deselects all other letters.

An optional letters to number toggle can precede the alphabet filters. Clicking the toggle button replaces the linked letters with linked numbers and changes the toggle button label from 0-9 to A-Z. Clicking the toggle again does the reverse.

Use alphabet filters when a very fast and easy to use row filter or navigation control will benefit users. Alphabet, and other toolbar filters, can also be used to manage performance issues by reducing result set size and therefore reducing the need for sorting and improving performance when sorts are performed.

Alphabet filters appear on the secondary toolbar. No other controls may be placed on the secondary toolbar.

The full set of attribute filters are mapped to a single column in the table. That column must correspond to a key attribute of the object that users are likely to want to filter on. In the large majority of cases, the attribute should be an object instance identifier. The filter column must also be visible and the leftmost column by default.

Selecting a letter adds an <attribute> Starts With condition to the query whose result set is displayed in the table. Selecting a letter highlights the selected letter and deselects all other letters.

When a set of alphanumeric filters is applied to a table column, QBE should be disabled for that column. See the QBE Design Pattern, the RCUX Table Elements Usage Guideline and Section 1.9 of the RCUX Tables UI Specification for more details about QBE usage, appearance, and behavior.

When alphabet filters and a search region are both in a single table, nonredundant criteria defined by alphabet filters (filters that do not correspond to search fields) are ANDed with the search criteria. Redundant criteria defined by alphabet filters override the corresponding search criteria.

For example, a search criterion of Supplier=Oracle plus the alphabet filter PO Starts With U yields the query Supplier=Oracle AND PO Starts With U. However, a search criterion of Supplier=Oracle plus the alphabet filter Supplier Starts With A yields the query Supplier Starts With A.

Alphabet filters, like other tooblar filters, should interact with a search region the same way that QBE filters native to ADF Table do (see the QBE design pattern). That is:

• Editing a redundant search field does not affect the state of the alphabet filter.
• Selecting a filter value overrides the redundant search field, but does not affect search field value shown in the UI. (The query shown in the search region will not match the query that generated the search results.)
• Saving the search does not save alphabet filter value. It only saves criteria specified in the search region.
• Selecting a saved search should not affect the state of the alphabet filter.