| |
| |
| """The gate used in README's 30-second example. |
| |
| A small validator that understands the subset of JSON Schema that |
| schema.json uses, so the example needs nothing installed. |
| |
| python gate.py <target-dir> # exit 0 = accept, exit 1 = reject |
| |
| Replace it with your own gate: a linter, a CI step, a policy check, an LLM |
| guardrail — anything that exits non-zero to mean "reject". |
| """ |
| import json |
| import sys |
| from pathlib import Path |
|
|
| TYPES = {"string": str, "integer": int, "number": (int, float), |
| "boolean": bool, "array": list, "object": dict} |
|
|
|
|
| def check(schema, value, path="$"): |
| """Return an error string, or None if the value satisfies the schema.""" |
| if not isinstance(schema, dict): |
| return "%s: the schema for this value is not an object" % path |
|
|
| t = schema.get("type") |
| if t is not None: |
| py = TYPES.get(t) |
| if py is None: |
| return "%s: schema declares an unknown type %r" % (path, t) |
| if isinstance(value, bool) and t != "boolean": |
| return "%s: expected %s, got boolean" % (path, t) |
| if not isinstance(value, py): |
| return "%s: expected %s, got %s" % (path, t, type(value).__name__) |
|
|
| if "enum" in schema and value not in schema["enum"]: |
| return "%s: %r is not one of %s" % (path, value, schema["enum"]) |
| if "minLength" in schema and isinstance(value, str) and len(value) < schema["minLength"]: |
| return "%s: shorter than minLength %d" % (path, schema["minLength"]) |
| if isinstance(value, (int, float)) and not isinstance(value, bool): |
| if "minimum" in schema and value < schema["minimum"]: |
| return "%s: %r is below minimum %s" % (path, value, schema["minimum"]) |
| if "maximum" in schema and value > schema["maximum"]: |
| return "%s: %r is above maximum %s" % (path, value, schema["maximum"]) |
| if "minItems" in schema and isinstance(value, list) and len(value) < schema["minItems"]: |
| return "%s: fewer than minItems %d" % (path, schema["minItems"]) |
|
|
| if isinstance(value, dict): |
| for key in schema.get("required", []): |
| if key not in value: |
| return "%s: missing required property %r" % (path, key) |
| for key, sub in schema.get("properties", {}).items(): |
| if key in value: |
| err = check(sub, value[key], "%s.%s" % (path, key)) |
| if err: |
| return err |
|
|
| if "items" in schema and isinstance(value, list): |
| for i, item in enumerate(value): |
| err = check(schema["items"], item, "%s[%d]" % (path, i)) |
| if err: |
| return err |
|
|
| return None |
|
|
|
|
| def main() -> int: |
| target = Path(sys.argv[1]) if len(sys.argv) > 1 else Path(".") |
| try: |
| schema = json.loads((target / "schema.json").read_text(encoding="utf-8")) |
| data = json.loads((target / "data.json").read_text(encoding="utf-8")) |
| except Exception as exc: |
| print("REJECT: cannot read the config: %s: %s" % (type(exc).__name__, exc)) |
| return 1 |
|
|
| err = check(schema, data) |
| if err: |
| print("REJECT: %s" % err) |
| return 1 |
|
|
| print("PASS: data.json satisfies schema.json") |
| return 0 |
|
|
|
|
| if __name__ == "__main__": |
| sys.exit(main()) |
|
|
