Priority forms are grouped within logical contexts into a tree-like configuration, representing one-to-many or one-to-one relationships. The root of the tree is the form which is accessed directly from a menu (e.g., Sales Orders); that is, it has no upper-level forms of its own. The branches of the tree are the sub-level forms of the root form, their sub-levels and so on. Any given form can have several sub-levels on the same level.
Example: Order Items and Tasks are both sub-levels of the Sales Orders form.
Relationships Between Upper- and Sub-level Forms
The relationship between an upper-level form and its sub-level may be:
- one-to-many — multiple records in the sub-level form are linked to a single record in the upper-level form
- one-to-one — a single record in the sub-level is linked to the record in the upper-level form.
Generally, the relationship between forms is one-to-many. For instance, each sales order can have several different order items. Sometimes, however, you wish to limit the sub-level form to a single record.
To obtain a one-to-one relationship, specify N in the One-to-Many column of the Form Generator form at the record for the sub-level form.
Linking Upper-level and Sub-level Forms
A sub-level form is used to display data that are relevant for a single record in its upper-level form. This linkage between the upper and sub-level form is executed through one or more columns. If the upper-level form has an autounique key, the link is made through the column comprising that key. Otherwise, the link is made through each column of its unique key.
Example: It is important to ensure that the parts ordered in Order 1000 are linked to the record of that order in the Sales Orders form, while the parts ordered in Order 1007 are linked to the record of that order. Thus, the ORD column in the Order Items form is equated with the ORD column in the Sales Orders form.
The linkage is created by means of a condition written for the relevant column in the sub-level form (e.g., the ORD column in the Order Items form).
In the case of an updatable sub-level (like Order Items), use the following format:
That is, begin with a colon, followed by the name of the upper-level form, a period, and finally the name of the column in the upper-level form to which the linkage is made (e.g., :ORDERS.ORD).
If the sub-level is a query form (like Warehouse Balances), add an equal sign to the beginning of the condition:
The addition of the equal sign allows users to delete records from the upper-level form even though records appear in the sub-level.
Specify this condition in the Expression/Condition column of the Form Column Extension form, a sub-level of the Form Columns form.
- You can use the double dollar sign (\() as a wildcard in place of the upper-level form name (e.g., :\).ORD). Moreover, if the link is made between columns having identical names, you can use the @ sign as a wildcard in place of the form column name (e.g., :$$.@).
- For a detailed explanation of conditions, see Conditions of Record Display and Insertion.
Creating a Form Tree
In addition to linking a sub-level form to its upper-level via their common record, you also have to locate them within a form tree. As a given upper-level form can have several sub-levels, you need to determine the order in which sub-levels appear (e.g., in the list of sub-levels). Each sub-level form’s position is defined by an integer: the lower the integer, the higher the position. Assign the lowest integer to the most frequently used sub-level form, which will then serve as the default sub-level. Integers need not be consecutive.
To link a sub-level form to its upper-level form and to define its position, use either the Sub-level Forms form or the Upper-level Forms form. Both are sub-levels of the Form Generator form.
Linking the Tree to a Menu
In addition, the root form of a form tree should be linked to a menu, from which it will be loaded (alternatively, the root form can be activated from within another form via an Action). As a menu generally contains several items, you are required to indicate the position of the root form within the menu (specify an integer). Again, the lower the integer, the higher the position of the form in relation to other items appearing in the menu.
Linkage between a root form and its menu is stored in the MENU table.
To link a root form to a menu and to define its position, use either the Menu/Form Link form, a sub-level of the Form Generator form, or the Menu Items form, a sub-level of the Menu Generator form.