diff --git a/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.bad.al b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.bad.al new file mode 100644 index 0000000..691dfd2 --- /dev/null +++ b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.bad.al @@ -0,0 +1,55 @@ +table 50123 "Transfer Source Bad" +{ + fields + { + field(1; "Entry No."; Integer) + { + DataClassification = CustomerContent; + } + field(2; "Reference"; Code[20]) + { + DataClassification = CustomerContent; + } + } + + keys + { + key(PK; "Entry No.") + { + Clustered = true; + } + } + +} + +table 50124 "Transfer Target Bad" +{ + fields + { + field(1; "Entry No."; Integer) + { + DataClassification = CustomerContent; + } + field(2; "Reference"; Integer) + { + DataClassification = CustomerContent; + } + } + + keys + { + key(PK; "Entry No.") + { + Clustered = true; + } + } + +} + +codeunit 50492 "TransferFields Bad" +{ + procedure CopyData(Source: Record "Transfer Source Bad"; var Target: Record "Transfer Target Bad") + begin + Target.TransferFields(Source, true, true); + end; +} \ No newline at end of file diff --git a/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.good.al b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.good.al new file mode 100644 index 0000000..a0ac2a8 --- /dev/null +++ b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.good.al @@ -0,0 +1,59 @@ +table 50121 "Transfer Source" +{ + fields + { + field(1; "Entry No."; Integer) + { + DataClassification = CustomerContent; + } + field(2; "Reference"; Code[20]) + { + DataClassification = CustomerContent; + } + } + + keys + { + key(PK; "Entry No.") + { + Clustered = true; + } + } + +} + +table 50122 "Transfer Target" +{ + fields + { + field(1; "Entry No."; Integer) + { + DataClassification = CustomerContent; + } + field(2; "Reference"; Integer) + { + DataClassification = CustomerContent; + } + } + + keys + { + key(PK; "Entry No.") + { + Clustered = true; + } + } + +} + +codeunit 50491 "TransferFields Good" +{ + procedure CopyData(Source: Record "Transfer Source"; var Target: Record "Transfer Target") + var + ConvertedReference: Integer; + begin + Target."Entry No." := Source."Entry No."; + Evaluate(ConvertedReference, Source."Reference"); + Target.Validate("Reference", ConvertedReference); + end; +} diff --git a/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.md b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.md new file mode 100644 index 0000000..a2ebeb6 --- /dev/null +++ b/community/knowledge/data-modeling/transferfields-skip-type-mismatch-can-drop-data.md @@ -0,0 +1,26 @@ +--- +bc-version: [16..] +domain: data-modeling +keywords: [transferfields, skipfieldsnotmatchingtype, type-mismatch, field-mapping, data-transfer] +technologies: [al] +countries: [w1] +application-area: [all] +--- + +# Do not use SkipFieldsNotMatchingType to hide required TransferFields mismatches + +## Description + +`Record.TransferFields` copies values between fields with matching field numbers. Without `SkipFieldsNotMatchingType` (or with it `false`), a type mismatch between two fields in the same extension raises a runtime error at the point of transfer. Setting `SkipFieldsNotMatchingType` to `true` removes that error: the field is skipped instead, and the rest of the transfer completes normally. The caller gets no indication that a field was not copied. + +## Best Practice + +Use `TransferFields(Source)` only when every field the destination requires, including primary key fields, is guaranteed to share a matching field number and type with the source; this form defaults `InitPrimaryKeyFields` to `true`. Fields with no matching field number, and fields whose types differ across extensions, are skipped regardless of `SkipFieldsNotMatchingType` — that parameter only governs same-extension type mismatches. If the destination depends on a field that falls into either case, map and validate it explicitly in code rather than relying on `TransferFields` to catch the gap. Use `SkipFieldsNotMatchingType = true` only when skipping same-extension type mismatches is an intentional, documented part of the transfer contract. + +## Anti Pattern + +Using `TransferFields(Source, InitPrimaryKeyFields, true)` as a generic way to make two evolving table schemas transfer without errors, when the destination depends on every required source field being copied. A type change on either table can turn a previously transferred field into a silently skipped one without making the transfer itself fail. + +See sample: `transferfields-skip-type-mismatch-can-drop-data.good.al`. + +See sample: `transferfields-skip-type-mismatch-can-drop-data.bad.al`.