Blog: Posts from June, 2012

Property Context Fields can pass values from the current record to the lookup data view. The value is passed as a map in the format LookupFieldName=LocalFieldName.

If LookupFieldName is an actual field in the lookup data view, then an automatic “equals” filter is applied to the view. The value of LocalFieldName data field is copied from the current record to the filter expression.

If the lookup view does not have a data field that matches LookupFieldName, then automatic filtering will not occur. Developers can specify a view Filter Expression or create a business rule to use the value to implement filtering.

Let’s create a Filter Expression for a lookup view that takes advantage of values passed in the Context Fields property.

Navigate to the Orders page and select an order. Create a new Order Details record, and activate the ProductID lookup.

A complete list of products (77 in total) will be displayed by default.

Let’s limit the set of products displayed to only those that are not already associated with the relevant order. If there is an OrderDetails record in the current order with a specific ProductID, then the product should not be displayed in the lookup.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab and double-click on OrderDetails / Fields / ProductID field node.

Change the Context Field property:

Press OK to save the field. Double-click on Products / Views / grid1 view node.

Notice that the ExistingOrderID field does not exist in the Products data controller. The application framework will not perform automatic filtering.

Change the Filter Expression:

@ContextFields_ExistingOrderID is null or ProductID not in
(
    select "OrderDetails"."ProductID" 
    from "Order Details" OrderDetails
    where OrderDetails.OrderID = 
        @ContextFields_ExistingOrderID
)

The ExistingOrderID field that was mapped in in the Context Fields property of OrderDetails.ProductID is referenced as @ContextFields_ExistingOrderID in the filter expression above. The application framework will automatically bind the parameter value.

Press OK to save the view. On the toolbar, press Browse.

Navigate to the Orders page, and select an order. Create a new order detail, and activate the ProductID lookup. The set of products available for selection will be limited to those that don’t exist for the order. As more OrderDetails records are added, the total number of products available for selection will gradually decrease.

Property Context Fields can list static values that can be used as lookup field filters.

For example, the CategoryID lookup field on the Products edit form displays eight categories available for selection.

Let’s specify static filter values for the CategoryID lookup data view.

Start the Project Designer. In the Project Explorer, switch to Controllers tab. Double-click on Products / Fields / CategoryID field node.

Change the Context Fields property:

Press OK to save the field.

CategoryID refers to the primary key of Categories controller. Any other data field in grid1 can be referenced as well.

On the toolbar, press Browse.

Navigate to the Products page, and edit a record. Activate the CategoryID lookup – only two items will be displayed.

If the lookup filter fields are text based, then the value must be surrounded by single quotes. For example, let’s use the field CategoryName as a context filter.

Change the Context Fields property of Products / Fields / CategoryID as shown next:

Press OK to save the field. On the toolbar, select Browse.

Navigate to Products page, and edit a record. Activate the CategoryID lookup – only two categories will be available for selection. Notice that the CategoryName field is hidden, since it is explicitly defined in the grid view.