mirror of
https://github.com/microsoft/BCQuality.git
synced 2026-10-05 14:46:55 +01:00
2b5550c346
Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules. Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
28 lines
1.4 KiB
Markdown
28 lines
1.4 KiB
Markdown
---
|
|
bc-version: [all]
|
|
domain: performance
|
|
keywords: [isempty, findset, extra-round-trip, existence-check, false-positive]
|
|
technologies: [al]
|
|
countries: [w1]
|
|
application-area: [all]
|
|
---
|
|
|
|
# IsEmpty immediately before FindSet is an extra round-trip
|
|
|
|
> Contributions welcome — open a PR to refine or extend this article.
|
|
|
|
## Description
|
|
|
|
`IsEmpty` is the right API when the caller only needs existence — see `microsoft/knowledge/performance/use-isempty-for-existence-check.md`. It is not a cheap guard in front of a loop that will `FindSet` anyway. Both calls hit the database; `FindSet` already returns false when the filter matches nothing. Agents and reviewers often insert `if not Rec.IsEmpty() then` "for performance" and pay a second query for a result the iterator already provides.
|
|
|
|
## Best Practice
|
|
|
|
When the body iterates, open with `if Rec.FindSet() then repeat ... until Next() = 0`. Do not flag a bare `FindSet` loop as missing an `IsEmpty` precondition. Reserve `IsEmpty` for branches that never materialize the row set.
|
|
|
|
See sample: [`isempty-before-findset-is-extra-round-trip.good.al`](isempty-before-findset-is-extra-round-trip.good.al).
|
|
|
|
## Anti Pattern
|
|
|
|
`if not Rec.IsEmpty() then if Rec.FindSet() then repeat`. Also a false-positive review comment that asks to add that guard. The second read does not avoid the first; it duplicates it.
|
|
|
|
See sample: [`isempty-before-findset-is-extra-round-trip.bad.al`](isempty-before-findset-is-extra-round-trip.bad.al).
|