Document error() function for @assert constraints#2541
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Adds a new "Error Functions" subsection under the @Assert annotation documentation explaining how to use the error() function to attach dynamic message parameters and explicit error targets to constraint violations. Includes signature table and three examples using the bookshop domain.
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We could also consider https://pages.github.tools.sap/cap/docs/java/event-handlers/indicating-errors as an alternative location for the documentation. (Daniel H. is still convinced that we should not offer the error function, as far as I know. @BraunMatthias - what do you think? |
agoerler
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Jun 2, 2026
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| | `parameters` | no | A single expression or a parenthesized list of expressions `(expr1, expr2, ...)` whose values are inserted into `{}` placeholders in the message. | | ||
| | `targets` | no | A single element reference or a parenthesized list of element references `(elem1, elem2, ...)` that the error should be attached to. The first target becomes the primary target; additional targets are reported as `@Common.additionalTargets`. | |
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clarify that if targets are given parameters is mandatory. null can be used as a placeholder
Co-authored-by: Adrian Görler <adrian.goerler@sap.com>
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Summary
@assert:annotation documentation inguides/services/constraints.mderror()function signature with all three arguments (message,parameters,targets)Books,price,minPrice,stock,quantity,title)Test plan
[!code focus]annotations highlight correctly in the introductory example#localized-messagesresolve correctly