45 lines
1.6 KiB
Python
45 lines
1.6 KiB
Python
"""Safe coercion of JSON-transported values into typed OPC write values.
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Fixes 1879 BUG-1 (bool('false') is True in Python) and BUG-2 (uncaught
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TypeError/ValueError from int/float on bad input).
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"""
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_FALSE_STRINGS = {'false', '0', 'no', 'off', ''}
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class ConversionError(ValueError):
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"""Raised when a raw value cannot be coerced to the requested type."""
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def _to_bool(raw) -> bool:
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if isinstance(raw, bool):
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return raw
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if isinstance(raw, (int, float)):
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return bool(raw)
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return str(raw).strip().lower() not in _FALSE_STRINGS
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def to_typed_value(raw, data_type: str):
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"""Coerce raw (often a JSON string) to the given data_type.
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data_type: 'boolean' | 'int' | 'float' | 'double' | 'string'.
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Raises ConversionError on any invalid input (never a bare TypeError).
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"""
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if not isinstance(data_type, str):
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raise ConversionError(f'data_type must be a string, got {type(data_type).__name__}')
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dtype = data_type.strip().lower()
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try:
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if dtype in ('bool', 'boolean'):
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return _to_bool(raw)
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if dtype in ('int', 'integer'):
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if isinstance(raw, str) and ('.' in raw or raw.strip() == ''):
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raise ConversionError(f'invalid int: {raw!r}')
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return int(raw)
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if dtype in ('float', 'double', 'real'):
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return float(raw)
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if dtype in ('str', 'string'):
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return str(raw)
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except (TypeError, ValueError) as e:
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raise ConversionError(f'cannot convert {raw!r} to {data_type}: {e}') from e
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raise ConversionError(f'unknown data_type: {data_type!r}')
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