Archive a Record with TransferFields

Medium

table

transferfields

flowfield

Archive a Record with TransferFields

Operations wants closed rental contracts out of the working table — but preserved forever, exactly as they looked on the day they were closed. That is the classic Business Central archive pattern (think Sales Header Archive): copy the row into an archive table with TransferFields, snapshot what the copy cannot carry, then delete the original.

TransferFields is the right tool, and this task is about its famous gotchas: it pairs fields by field number (same number + compatible type = copied; anything else = silently left alone), it never calculates a FlowField, and it never runs any OnValidate trigger.

What you are given

The starter contains two finished tables — submit them unchanged alongside your new objects:

Table "Rental Contract": field 1 "No." (Code[20], PK), field 2 "Customer Name" (Text[100]), field 3 "Monthly Fee" (Decimal, with an OnValidate that rejects negative values), field 4 "Start Date" (Date), and field 20 "Total Charges" — a FlowField summing "Rental Charge".Amount for the contract.
Table "Rental Charge": the charge lines behind that FlowField, keyed "Contract No." + "Line No.".

Requirements

Finish table "Rental Contract Archive" so that TransferFields can carry the contract over: it needs "No." (Code[20], PK — already there), "Customer Name" (Text[100]), "Monthly Fee" (Decimal), "Start Date" (Date), and "Total Charges" (Decimal) — plus a Date field named "Archived On" that exists only in the archive. Field numbers are yours to choose, but choose them knowing how TransferFields pairs fields.
In the archive, "Total Charges" must be a normal field: the archive stores a frozen snapshot of the total at archive time, because the charge lines may be cleaned up later and the archive must not depend on them.
Implement codeunit "Contract Archiver" with this exact procedure:

procedure Archive(ContractNo: Code[20]; ArchivedOn: Date)

Archive must:

copy the contract's stored fields ("Customer Name", "Monthly Fee", "Start Date") onto an archive row with the same "No.";
store the contract's calculated "Total Charges" in the archive — remember: TransferFields does not calculate a FlowField, and a freshly read record carries 0 in it;
stamp the archive row's "Archived On" with the ArchivedOn parameter — TransferFields cannot fill a field the source table does not have;
copy values exactly as stored, without running validation: a legacy contract whose "Monthly Fee" is negative (inserted before today's rule existed) must archive without an error and keep its negative fee;
delete the original "Rental Contract" row — archiving moves the record;
leave the "Rental Charge" lines untouched — a separate cleanup job owns them;
fail with an error and write nothing when no contract with the given number exists.

What the tests check

The tests seed contracts (with generated names, fees, dates and charge amounts), call Archive once, and then read your archive table directly, finding each field by name (so spell them exactly as listed): the copied fields, the snapshotted total (also after another charge line is added later — the archived total must not move), the "Archived On" stamp, the deleted original, the surviving charge lines, the raw copy of a negative legacy fee, and the error path for a missing contract number. The archived total is read straight from the field, so an archive "Total Charges" declared as a FlowField reads 0 and fails.

Learn More

Hint 1

TransferFields copies wherever source and destination FIELD NUMBERS match and the types are compatible; everything else is silently left alone. Mirror the contract's field numbers in the archive, and give "Archived On" a number the contract does not use.

Hint 2

Two things TransferFields never does: calculate a FlowField (a freshly read record carries 0 in "Total Charges") and run OnValidate. Whatever those would have produced, your code must produce explicitly — and that no-validation behavior is exactly why the negative legacy fee archives cleanly.

Hint 3

The archiver's shape: Get the contract, CalcFields the total, Init the archive record, TransferFields from the contract, explicitly set "Total Charges" (from the calculated source field) and "Archived On", Insert the archive row, Delete the contract.

ALBusiness Central 28.5

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