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Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 667c64a8-eb36-4440-bc41-6a97d8fb5542
26 lines
1.3 KiB
Markdown
26 lines
1.3 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [report, addloadfields, onpredataitem, dataitem, partial-record, layout]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# Add trigger-only report fields in OnPreDataItem
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## Description
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Report dataitem field selection is calculated at compile time and once per dataitem type during execution. Fields referenced by dataset columns are selected automatically; fields used only in triggers are not. Use `AddLoadFields` in `OnPreDataItem` to supplement the automatic selection with normal fields that trigger code needs.
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## Best Practice
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When a dataitem trigger needs an extra field, add that field in `OnPreDataItem` before iteration starts. This supplements the compiler-selected fields and avoids the first just-in-time load and enumerator update when the trigger reads the extra field.
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See sample: `addloadfields-in-report-onpredataitem.good.al`.
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## Anti Pattern
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Listing every dataset column in `AddLoadFields`, or omitting a known trigger-only field because the dataset already uses other fields. The former is redundant; the latter causes a just-in-time load on first access and can cause repeated loads when the record is copied or passed by value.
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See sample: `addloadfields-in-report-onpredataitem.bad.al`.
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