Mark code-required page fields with ShowMandatory

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Description

ShowMandatory draws the red asterisk on a page field and, per the platform documentation, enforces no validation. The reverse holds too: code that enforces a value — TestField in OnInsert/OnModify, a NotBlank table field, a mandatory setup value — changes nothing about how the field renders. Because the two halves are independent, it is easy to ship a field that the code requires but the UI presents as optional. NotBlank does not close the gap: the documentation confines any marking it may contribute to primary-key fields, states that on any other field a value which was never entered is not validated at all, and notes that ShowMandatory overrides whatever marking NotBlank would contribute — so ShowMandatory is the only property to rely on for the asterisk. The gap is widest on a list page with DelayedInsert = true, where the enforcing error surfaces only when the user leaves the row — after the rest of the line is typed, with nothing having indicated which field was missing.

Best Practice

Set ShowMandatory = true on every page field whose value the code requires before the record can be committed, and leave the enforcement in place: the property is presentation, TestField/Error is the guarantee, and the two belong together in the same change. When the requirement is conditional, bind ShowMandatory to a Boolean variable or field that mirrors the condition the enforcement checks — the base application drives Vendor Invoice No. on the Purchase Invoice page from an Ext. Doc. No. Mandatory setup flag this way. Two expression limits are worth knowing: the property cannot call an AL method, so compute the value into a variable first, and a numeric field that has a default value counts as filled, so it never shows the asterisk. See sample: showmandatory-on-code-required-page-fields.good.al.

Anti Pattern

A required field with no mandatory marker: the table's OnInsert or the page's OnInsertRecord calls TestField on a field, or NotBlank on a non-primary-key field is expected to force entry, while the page field bound to it carries no ShowMandatory. On a DelayedInsert = true list page the user fills the row, leaves it, and gets an error naming a field that never looked different from the optional ones. Reviewer signal: a TestField or Error naming a field in OnInsert, OnInsertRecord, OnModify, or OnValidate, or NotBlank = true on a table field, with no ShowMandatory on the corresponding page field — exactly the review finding on the Job Assigned Resources page linked below. Setting ShowMandatory = false on a required field is the same defect stated explicitly, and per the documentation it also overrides any marking NotBlank would otherwise contribute. See sample: showmandatory-on-code-required-page-fields.bad.al.

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Mark code-required page fields with ShowMandatory

Description

Best Practice

Anti Pattern

See also

3.5 KiB

Raw Blame History