Filtering

As mentioned earlier, filtering is one of the very powerful tools within NAV C/AL. Filtering is the application of defined limits on the data to be considered in a process (to learn more about Data types in NAV, visit here). Filter structures can be applied in at least three different ways, depending on the design of the process. The first way is for the developer to fully define the filter structure and the value of the filter. This might be done in a report designed to show only information on a selected group of customers, for example those with an open Balance on Account. The Customer table would be filtered to report only customers who have an Outstanding Balance greater than zero.

The second way is for the developer to define the filter structure, but allow the user to fill in the specific value to be applied. This approach would be appropriate in an accounting report that was to be tied to specific accounting periods. The user would be allowed to define what period(s) were to be considered for each report run.

The third way is the ad hoc definition of a filter structure and value by the user. This approach is often used for general analysis of ledger data where the developer wants to give the user total flexibility in how they slice and dice the available data.

It is quite common within the standard NAV applications and in the course of enhancements to use a combination of the different filtering types. For example, the report just mentioned that lists only customers with an open Balance on Account (via a developer-defined filter) could also allow the user to define additional filter criteria. Perhaps, the user wants to see only Euro currency-based customers, so they would filter on the Customer Currency Code field.

Filters are an integral part of FlowFields and FlowFilters, two of the three Field Classes. These are very flexible and powerful tools, which allow the NAV designer to create forms, reports, and other processes that can be used by the user under a wide variety of circumstances for various purposes. In most systems, user inquiries (forms and reports) and processes need to be quite specific to different data types and ranges. The NAV C/AL toolset allows you to create relatively generic user inquiries and processes and then allow the user to apply filtering to fit their specific needs.

Defining Filter Syntax and Values

Let us go over some common ways in which we can define filter values and syntax. Remember, when you apply a filter, you will only view or process records where the filtered data field satisfies the limits defined by the filter.

Equality and inequalityeither an equal (=) sign or no sign filters for data “equal to” the filter value.

        a greater than (>) sign filters for data greater than the filter value

        a less than (<) sign filters for data less than the filter value