C/AL to AL: The Complete Migration Cheat Sheet (2026 Edition)

If you learned C/AL in the Dynamics NAV era, the good news is that most of your knowledge still applies. AL, the language of Microsoft Dynamics 365 Business Central, kept the core concepts — tables, pages, codeunits, triggers but modernized the syntax and moved everything to an extension-based model. C/AL and the classic C/SIDE environment were retired back in Business Central version 15 (2019), and as of 2026 we are already 13 major versions into the fully AL-based world.

This cheat sheet maps the most common C/AL patterns to their AL equivalents so you can migrate old code (or old skills) quickly.

1. The big picture: what changed

ConceptC/AL (NAV)AL (Business Central)
Development toolC/SIDE (Object Designer)Visual Studio Code + AL Language extension
Customization modelModify base objects directlyExtensions only never modify the base app
Object filesStored in the databasePlain-text .al files in a project, version-controlled with Git
DeploymentImport .fob / .txt filesPublish .app packages (extensions)
New object types—Table extension, page extension, enum, interface, report extension, permission set

2. Object declaration

In C/SIDE you created objects through the Object Designer. In AL, every object is code. A table now looks like this:

table 50100 "My Customer Rating"
{
    DataClassification = CustomerContent;

    fields
    {
        field(1; "Customer No."; Code[20])
        {
            TableRelation = Customer."No.";
        }
        field(2; Rating; Integer) { }
    }

    keys
    {
        key(PK; "Customer No.") { Clustered = true; }
    }
}

Instead of modifying the standard Customer table, you extend it:

tableextension 50100 "Customer Ext" extends Customer
{
    fields
    {
        field(50100; "Loyalty Level"; Option)
        {
            OptionMembers = None,Bronze,Silver,Gold;
        }
    }
}

3. Syntax cheat sheet

TaskC/ALAL
Declare a functionPROCEDURE MyFunc@1() : Boolean;procedure MyFunc(): Boolean
Local variablesVAR section in a separate windowvar block written inline above begin
Text constantsText001@1000 : TextConst 'ENU=Hello';HelloLbl: Label 'Hello';
OptionsOptionString property on a fieldPrefer enum objects (extensible!)
Case of keywordsIF ... THEN ... ELSE (uppercase)if ... then ... else (lowercase)
Record filteringSETRANGE, SETFILTER, FINDSETSame methods, lowercase: SetRange, SetFilter, FindSet
DialogsMESSAGE, ERROR, CONFIRMMessage, Error, Confirm — plus ErrorInfo for actionable errors
.NET interopDotNet variablesNot available in the cloud — use HttpClient, JsonObject, XmlDocument AL types instead

4. Enums replace Options

The single most useful new concept. Options in C/AL could not be extended by other developers; enums can:

enum 50100 "Loyalty Level"
{
    Extensible = true;

    value(0; None) { Caption = 'None'; }
    value(1; Bronze) { Caption = 'Bronze'; }
    value(2; Silver) { Caption = 'Silver'; }
    value(3; Gold) { Caption = 'Gold'; }
}

5. Events replace direct modifications

In NAV you would edit Codeunit 80 to change posting behavior. In AL you subscribe to events instead, so your change survives every upgrade:

codeunit 50100 "Sales Post Subscriber"
{
    [EventSubscriber(ObjectType::Codeunit, Codeunit::"Sales-Post",
        OnBeforePostSalesDoc, '', false, false)]
    local procedure CheckLoyaltyOnPost(var SalesHeader: Record "Sales Header")
    begin
        // your logic here, upgrade-safe
    end;
}

6. Web services and files

Old patterns that relied on DotNet, FILE, or automation objects need rethinking in the cloud:

  • HTTP calls: use the built-in HttpClient, HttpRequestMessage, and HttpResponseMessage types.
  • JSON: use JsonObject, JsonArray, JsonToken.
  • Files: there is no server file system in SaaS. Use InStream/OutStream with UploadIntoStream and DownloadFromStream, or Blob storage.

7. Tools that do the heavy lifting

  • Txt2AL — converts exported C/AL .txt objects into .al files. A great starting point, though the output usually needs cleanup.
  • AL Language extension for VS Code — IntelliSense, snippets (type ttable, tpage, tcodeunit), and one-key publishing with F5.
  • AZ AL Dev Tools / AL Code Outline — community extension that massively speeds up refactoring.
  • Cloud migration tooling — for moving data from NAV on-premises to Business Central online once your customizations are extensions.

8. Upgrade path reality check (2026)

If you are still on an old NAV version, you cannot jump straight to the current release. Older on-premises deployments must first upgrade to an intermediate supported version before moving to version 28 (2026 release wave 1), and all customizations must be converted to extensions before a cloud migration. Budget real time for this — the technical conversion is often the easy part compared to testing.

Final thoughts

C/AL knowledge is not wasted — it is the foundation. The business logic, table structures, and posting routines you know from NAV are still recognizably there. What changed is how you touch them: through extensions, events, and modern tooling. Learn enums, events, and the VS Code workflow, and you are 80% of the way to being a productive AL developer.

Have a specific C/AL pattern you are struggling to convert? Drop it in the comments and I will cover it in a future post.

Comments

Post a Comment

Popular posts from this blog

IF - THEN And IF - THEN - ELSE Satement In Microsoft Dynamics NAV

IF Satement In Microsoft Dynamics NAV IF Statement is the most commonly used conditional statement that work based upon the statement is TRUE or FALSE. Conditional Statements works like first check one condition and based upon the result of this condition further flow of the program happened. Microsoft Dynamics NAV(previously Navision) language C/AL is used other conditional statements too. If statement or IF loop is used execute a code when a purticular statement is TRUE only and some case its used to execute some statements when the statement is FALSE too. There are mainly 2 types of IF statement specifications IF - THEN Syntax IF - THEN - ELSE Syntax IF - THEN Syntax : - In this type of IF statements you have to use following type of syntax IF boolean expression THEN  statement This statement works in a manner that first the Boolean expression is evaluated and if the value is TRUE then the Statement excuted and if the Boolean expression is FALSE then the statements after the IF sta...
Read more

WITH Loop / Statement

WITH Loop / Statement WITH Statement or loop is used to make record variables easier.  Record variable is a complex datatype with one variable we can store multiple values like arrays. Each record having different fields and each of these fields can able to store different data types also. These fields are separated by the ' . ' or dot sign. If a customer record having field named Name then it can be specified like customer.Name Syntax Of WITH Loop Suppose we having three fields names name, address and City then it can be specified in the recod named customer as folows      customer.Name := Txt[1];      customer.Address := Txt[2];      customer.City := Txt[3]; We can sort these kind of representation in the system different way so that we can minimise the number of codings that syntax of WITH Loop is as follows ----------------------------------------------------------------------------            WITH Record Variable DO Statement ---------------------------------------------...
Read more

CASE

CASE Loop or Statements CASE Loop or statements is a conditional statement.  Like IF loop or statement these also works in the manner that once the statement is true then some statements are executed other wise the else part will be executed. But in the case of CASE we can consolidate muliple levels of IFloops in one CASE. Some programming languages like C its called as SWITCH - CASE loop but in Navision or Microsoft Dynamics NAV we called this as CASE only. Syntax of CASE  -----------------------------------------------------------         CASE Expression OF                Value Set 1 : Statement 1;                Value Set 2 : Statement 2;                  ...                Value Set n : Statement n;               ELSE Statement n+1;          END   ----------------------------------------------------------- A sample program for the CASE is as follows ==============================================================      CASE Color OF            Color :: Orange:                        ...
Read more