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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>
32 lines
2 KiB
Markdown
32 lines
2 KiB
Markdown
---
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bc-version: [all]
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domain: upgrade
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keywords: [initvalue, new-field, existing-rows, default-value, table-extension]
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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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# `InitValue` does not back-fill existing rows
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## Description
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`InitValue` on a field defines the value the platform assigns when a *new* record is inserted. It does not touch rows that already exist when the field is added. When a new field is added to an existing table — directly or via a table extension — every pre-existing row receives the datatype default (`false` for Boolean, `0` for numeric, empty for text), not the `InitValue`. If the intended semantics require existing rows to carry the `InitValue`, the change is incomplete without an upgrade routine that sets the field on those rows.
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Several legitimate cases do NOT need upgrade code:
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- New fields on brand-new tables (no existing rows).
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- New `Boolean` fields without `InitValue` where the datatype default `false` is the intended value.
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- New fields on configuration / setup tables that have no meaningful "existing data".
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- Informational or optional fields (logging, preferences, tracking) where `false` / empty is a valid state.
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## Best Practice
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When a new field on an existing table has an `InitValue` that matters, ship an upgrade procedure that walks the existing rows and sets the field to the same value — typically via `DataTransfer.AddConstantValue` for performance — guarded by an upgrade tag.
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See sample: [`initvalue-does-not-update-existing-rows.good.al`](initvalue-does-not-update-existing-rows.good.al).
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## Anti Pattern
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Adding a field with `InitValue = true;` (or any non-default `InitValue`) and shipping no upgrade code. Existing rows silently carry the datatype default, leaving the table in two states: rows created before the upgrade with the wrong value, and rows created after with the right one.
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See sample: [`initvalue-does-not-update-existing-rows.bad.al`](initvalue-does-not-update-existing-rows.bad.al).
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