Fix: Validate additional field length before FieldRef.Validate in E-Doc finalization

[ventselartur]

Summary

Fixes AB#623716 — [Payables Agent] Draft could not be finalised due to field length issues.

Initial Analysis: Direct Assignments Are Safe

All direct field assignments in EDocCreatePurchaseInvoice.Codeunit.al from E-Document tables to Purchase Header/Line tables are safe:

• Code[20] → Code[20]: [BC] Purchase Type No., [BC] Shortcut Dimension 1/2 Code all flow to matching-length Purchase Line fields via Validate
• Text[100] → Text[100]: Description and Posting Description match on both sides
• CopyStr-protected: Unit of Measure Code (line 213) and Vendor Invoice No. (line 139) explicitly truncate with CopyStr/MaxStrLen

No overflow can occur through these paths — if the E-Doc table fields are properly populated, all values fit.

The Actual Vulnerability: ApplyAdditionalFieldsFromHistoryToPurchaseLine

The call on line 235 of EDocCreatePurchaseInvoice.Codeunit.al delegates to EDocPurchaseHistMapping.Codeunit.al, where the procedure uses a FieldRef variable to dynamically validate values onto Purchase Line fields:

NewPurchLineFieldRef := NewPurchLineRecordRef.Field(EDocPurchLineFieldSetup."Field No.");
NewPurchLineFieldRef.Validate(EDocPurchLineField.GetValue());

The problem: E-Document Line - Field stores values in Text[2048] and Code[2048] fields. GetValue() returns these wide values, and FieldRef.Validate() pushes them directly into Purchase Line fields that can be as narrow as Code[20] — with no length check.

This is the path that produces the runtime error: a value like "MONTHLY SUBSCRIPTIONS" (21 chars) stored in Code[2048] overflows a Code[20] target field during finalization.

Fix Applied

Added a CheckFieldValueLength guard before FieldRef.Validate() that uses FieldRef.Length() to compare the target field's max size against the value length, and FieldRef.FieldError() with Name() and Number() to produce an actionable error identifying the problematic additional field by name and ID.

Test plan

• Configure an additional field on E-Doc Purchase Line Field Setup that maps to a Code[20] field
• Create an e-document draft where the additional field value exceeds 20 characters
• Finalize the draft and verify the error message identifies the field by name and ID
• Verify that valid-length values still finalize successfully

🤖 Generated with Claude Code

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