| bc-version |
domain |
keywords |
technologies |
countries |
application-area |
|
|
patterns |
| maxstrlen |
| copystr |
| truncation |
| magic-number |
| field-length |
| overflow |
| string |
|
|
|
|
CMFRT use MaxStrLen in CopyStr, never a literal length
Description
When CMFRT code truncates a text value to fit a field, the length argument of CopyStr must be MaxStrLen(TargetRecord.TargetField), never a numeric literal. The field is the single source of truth for its own length; a hardcoded number silently diverges the moment the field is widened or the code is copied to a field of a different size, producing either needless truncation or a runtime overflow error.
Best Practice
Write Rec."CMFRT AQ User ID" := CopyStr(UserId(), 1, MaxStrLen(Rec."CMFRT AQ User ID"));. The expression stays correct through any future field-length change and documents intent: truncate to whatever fits the target.
See sample: cmfrt-maxstrlen-copystr.good.al.
Anti Pattern
CopyStr(UserId(), 1, 50) — the literal encodes the field length at the time of writing. Widening the field leaves data truncated at the stale length; narrowing it turns the assignment into a runtime "length exceeds" error that only fires on long values in production.
See sample: cmfrt-maxstrlen-copystr.bad.al.
