Use expressions where they belong, not as mini scripts.
Ignition expressions have their own syntax, refresh behavior, and failure modes. This skill helps the AI name the surface first, write the smallest useful expression, and check the returned value, type, and quality.
Why it was made
- Keeps Jython imports, assignments, loops, SQL clauses, and side effects out of expression-only contexts.
- Separates Expression Tags, UDT expression members, Derived Tags, Perspective bindings, Vision bindings, transforms, and tag-binding expression mode.
- Uses real expression-language patterns for if, case, switch, coalesce, try, type conversion, date formatting, datasets, JSON, and quality checks.
- Treats tag(), dynamic paths, and runScript() as boundary decisions that need validation, especially on busy screens.
Common use cases
- Dynamic labels, state text, colors, and enable/visible bindings.
- Expression Tags and UDT calculated members.
- Quality-aware status logic for equipment faceplates.
- Refactoring messy nested logic into safer expression patterns.
Proof style
Validate the artifact, not the promise.
The skill asks the AI to validate expression value, type, quality, surface, refresh behavior, and fallback behavior instead of stopping at parse-only checks.
Evidence
Expression validation workflow proof
The graphic is AI-generated for the site. The checks below come from sanitized expression-language evidence: live Ignition 8.1.53 Expression Tag fixtures, UDT expression members, Derived Tags, quality and fallback matrices, numeric/date/dataset/JSON edge cases, runScript boundary checks, and packaging smoke scans. Perspective and Vision expression guidance still needs target-side client validation.
- Live Gateway runs verified value and quality readbacks for Expression Tags across arithmetic, booleans, dates, strings, JSON, DataSets, quality helpers, dynamic tag paths, and fallback cases.
- UDT expression-member and Derived Tag runs covered parameter syntax, sibling members, DataSet members, JSON read/writeback, retargeting, and read-only write rejection.
- runScript tests kept polling, Gateway scripting scope, and performance caveats separate from normal expression use.
- Perspective structural route/view checks passed in a diagnostic run, but browser evidence showed View Not Found, so no Perspective runtime binding facts were promoted.
- Product packaging checks verified the public skill zip includes only SKILL.md, agents/openai.yaml, and the expression test-matrix reference.
Example prompt
Create a Perspective expression for a pump label color: red when faulted, yellow when running but low flow, green when running normally, gray when stopped.This is the kind of short instruction the skill is designed to make useful. The value is in the checks and Ignition-specific defaults the AI uses after reading the skill.
Expected output
- Names the surface as a Perspective expression binding before writing syntax.
- Uses a case(true, ...) pattern driven by view custom properties instead of hardcoded tag paths.
- Adds a validation note for returned color string, property type, null inputs, and source quality.
Related workflows
Skills that pair with this one
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