bcquality/microsoft/knowledge/data-modeling/check-post-line-batch-pattern.md

bc-version	domain	keywords	technologies	countries	application-area
all	data-modeling	posting-routine check-line post-line post-batch companion-codeunit yes-no-wrapper journal	al	w1	all

Split posting routines into Check Line / Post Line / Post Batch

Contributions welcome — open a PR to refine or extend this article.

Description

Every journal-based posting routine in Business Central is split across three companion codeunits with distinct, non-overlapping responsibilities: Check Line validates one line, Post Line writes exactly one line to the ledger, and Post Batch loops both across the journal. A document posting routine (posting one document at a time) calls Post Line directly and skips Post Batch. A new posting routine that blurs this split either misses functionality other code expects to call directly, or exposes an interaction surface it shouldn't.

Best Practice

Check Line reads setup/dimension data only on its first call and shows no UI beyond errors. Post Line only operates on the record passed to it — never the Journal table — so it can be called directly by other posting code, including a document posting routine. Post Batch is the only one of the three that reads and updates the Journal table, and it is the only one invoked from the Post action on a journal page. A -Post document codeunit is never called directly from a page; a page calls a -Post (Yes/No) confirmation wrapper instead, so the same -Post codeunit can also run unattended from a batch-posting report.

See sample: check-post-line-batch-pattern.good.al.

Anti Pattern

A single monolithic posting codeunit that reads the Journal table, validates lines, writes ledger entries, and shows confirmation dialogs all in one procedure. It cannot be reused by another posting routine without fabricating journal records, and it cannot run unattended because it insists on user interaction.

See sample: check-post-line-batch-pattern.bad.al.