rohitg00/ai-engineering-from-scratch · error · ValueError

rule {r.get('name')} missing required field

Error message

rule {r.get('name')} missing required field

What it means

Error "rule {r.get('name')} missing required field" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/19-capstone-projects/86-constitutional-rules-engine/code/main.py:139

        return (wc >= int(node["min_words"])), (f"word count {wc}" if wc < int(node["min_words"]) else None)
    raise ValueError(f"unknown predicate: {list(node.keys())}")


class Engine:
    def __init__(self, rules: list[dict[str, Any]] | None = None, path: Path | None = None) -> None:
        if rules is not None:
            self._rules = rules
        else:
            target = path or DEFAULT_RULES_PATH
            data = load_yaml(target.read_text())
            if not isinstance(data, dict) or "rules" not in data:
                raise ValueError("constitution must be a mapping with a 'rules' key")
            self._rules = data["rules"]
        for r in self._rules:
            if r.get("severity") not in SEVERITY_ORDER:
                raise ValueError(f"rule {r.get('name')} has bad severity {r.get('severity')}")
            if "name" not in r or "explanation" not in r or "must" not in r:
                raise ValueError(f"rule {r.get('name')} missing required field")

    def rules(self) -> list[dict[str, Any]]:
        return list(self._rules)

    def evaluate(self, text: str) -> EngineReport:
        report = EngineReport(text=text)
        for rule in self._rules:
            name = str(rule["name"])
            sev = str(rule["severity"])
            expl = str(rule["explanation"])
            applies, _ = _eval_predicate(rule.get("applies_when"), text)
            if not applies:
                report.results.append(
                    RuleResult(rule_name=name, severity=sev, status="not_applicable", explanation=expl)
                )
                continue
            satisfied, span = _eval_predicate(rule["must"], text)
            if satisfied:

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/19-capstone-projects/86-constitutional-rules-engine/code/main.py:139 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/841453035c047a66. Report an issue: GitHub.