bcquality/microsoft/knowledge/performance/addloadfields-in-report-onpredataitem.md

bc-version	domain	keywords	technologies	countries	application-area
all	performance	report addloadfields onpredataitem dataitem partial-record layout	al	w1	all

Add trigger-only report fields in OnPreDataItem

Description

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.

Best Practice

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.

See sample: addloadfields-in-report-onpredataitem.good.al.

Anti Pattern

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.

See sample: addloadfields-in-report-onpredataitem.bad.al.