Programming in C/AL
This section describes where to write C/AL code and how to reuse code.
For more information about how to use system-defined variables, see System-Defined Variables.
For more information about the most frequently used C/AL functions, see Essential C/AL Functions.
Where to Write C/AL Code
Almost every object in Dynamics NAV contains triggers where you can add your C/AL code. Triggers exist for the following objects:
Tables
Table fields
Pages, including request pages
Reports
Data items
XMLports
Queries
You can initiate the execution of your C/AL code from the following:
Actions
Menu items
Any object that has an instantiation of the object that contains C/AL code. An example of an instantiation is a variable declaration.
Note
If the C/AL code is in a local function, then you cannot run it from another object.
Guidelines for Placing C/AL Code
We recommend the following guidelines for C/AL code:
In general, put the code in codeunits instead of on the object on which it operates. This promotes a clean design and provides the ability to reuse code. It also helps enforce security. For example, typically users do not have direct access to tables that contain sensitive data, such as the General Ledger Entry table, nor do they have permission to modify objects. If you put the code that operates on the general ledger in a codeunit, give the codeunit access to the table, and give the user permission to execute the codeunit, then you will not compromise the security of the table and the user will be able to access the table.
If you must put code on an object instead of in a codeunit, then put the code as close as possible to the object on which it operates. For example, put code that modifies records in the triggers of the table fields.
Reusing Code
Reusing code makes developing applications both faster and easier. More importantly, if you organize your C/AL code as suggested, your applications will be less prone to errors. By centralizing the code, you will not unintentionally create inconsistencies by performing the same calculation in many places, for example, in several triggers that have the same table field as their source expression. If you have to change the code, you could either forget about some of these triggers or make a mistake when you modify one of them.