json-parser

建設データ用 JSON パーサー

概要

建設システムでは、IoT センサーから BIM メタデータのエクスポートまで、データ交換に JSON がますます利用されるようになっています。このスキルでは、JSON 構造の解析、検証、フラット化を行います。

Python の実装

import json
import pandas as pd
from typing import Dict, Any, List, Optional, Union
from dataclasses import dataclass
from pathlib import Path


@dataclass
class JSONParseResult:
    """Result of JSON parsing operation."""
    success: bool
    data: Any
    errors: List[str]
    record_count: int


class ConstructionJSONParser:
    """Parse JSON data from construction sources."""

    def __init__(self):
        self.errors: List[str] = []

    def parse_file(self, file_path: str) -> JSONParseResult:
        """Parse JSON from file."""
        try:
            with open(file_path, 'r', encoding='utf-8') as f:
                data = json.load(f)
            return JSONParseResult(True, data, [], self._count_records(data))
        except json.JSONDecodeError as e:
            return JSONParseResult(False, None, [f"JSON Error: {e}"], 0)
        except Exception as e:
            return JSONParseResult(False, None, [str(e)], 0)

    def parse_string(self, json_string: str) -> JSONParseResult:
        """Parse JSON from string."""
        try:
            data = json.loads(json_string)
            return JSONParseResult(True, data, [], self._count_records(data))
        except json.JSONDecodeError as e:
            return JSONParseResult(False, None, [f"JSON Error: {e}"], 0)

    def _count_records(self, data: Any) -> int:
        """Count records in data."""
        if isinstance(data, list):
            return len(data)
        elif isinstance(data, dict):
            return 1
        return 0

    def flatten_json(self, data: Dict, prefix: str = '') -> Dict[str, Any]:
        """Flatten nested JSON to single-level dict."""
        flat = {}
        for key, value in data.items():
            new_key = f"{prefix}_{key}" if prefix else key

            if isinstance(value, dict):
                flat.update(self.flatten_json(value, new_key))
            elif isinstance(value, list):
                if all(isinstance(i, (str, int, float, bool, type(None))) for i in value):
                    flat[new_key] = value
                else:
                    for i, item in enumerate(value):
                        if isinstance(item, dict):
                            flat.update(self.flatten_json(item, f"{new_key}_{i}"))
                        else:
                            flat[f"{new_key}_{i}"] = item
            else:
                flat[new_key] = value
        return flat

    def to_dataframe(self, data: Union[List[Dict], Dict]) -> pd.DataFrame:
        """Convert JSON data to DataFrame."""
        if isinstance(data, list):
            flat_records = [self.flatten_json(r) if isinstance(r, dict) else {'value': r} for r in data]
            return pd.DataFrame(flat_records)
        elif isinstance(data, dict):
            if all(isinstance(v, list) for v in data.values()):
                # Dict of lists - columnar format
                return pd.DataFrame(data)
            else:
                flat = self.flatten_json(data)
                return pd.DataFrame([flat])
        return pd.DataFrame()

    def extract_elements(self, data: Dict, path: str) -> List[Any]:
        """Extract elements using dot notation path."""
        parts = path.split('.')
        current = data

        for part in parts:
            if isinstance(current, dict) and part in current:
                current = current[part]
            elif isinstance(current, list) and part.isdigit():
                current = current[int(part)]
            else:
                return []

        return current if isinstance(current, list) else [current]

    def validate_schema(self, data: Dict,
                        required_fields: List[str]) -> Dict[str, Any]:
        """Validate JSON against required fields."""
        flat = self.flatten_json(data)
        missing = [f for f in required_fields if f not in flat]
        present = [f for f in required_fields if f in flat]

        return {
            'valid': len(missing) == 0,
            'missing_fields': missing,
            'present_fields': present,
            'completeness': len(present) / len(required_fields) * 100
        }


# BIM JSON Parser
class BIMJSONParser(ConstructionJSONParser):
    """Specialized parser for BIM JSON exports."""

    def parse_bim_elements(self, data: Dict) -> pd.DataFrame:
        """Parse BIM elements from JSON export."""
        elements = []

        # Common BIM JSON structures
        if 'elements' in data:
            elements = data['elements']
        elif 'objects' in data:
            elements = data['objects']
        elif 'entities' in data:
            elements = data['entities']
        elif isinstance(data, list):
            elements = data

        if not elements:
            return pd.DataFrame()

        # Flatten each element
        flat_elements = []
        for elem in elements:
            if isinstance(elem, dict):
                flat = self.flatten_json(elem)
                flat_elements.append(flat)

        return pd.DataFrame(flat_elements)

    def extract_properties(self, element: Dict) -> Dict[str, Any]:
        """Extract properties from BIM element."""
        props = {}

        # Common property locations in BIM JSON
        for key in ['properties', 'params', 'parameters', 'attributes']:
            if key in element and isinstance(element[key], dict):
                props.update(element[key])

        return props


# IoT JSON Parser
class IoTJSONParser(ConstructionJSONParser):
    """Parser for IoT sensor data."""

    def parse_sensor_reading(self, data: Dict) -> Dict[str, Any]:
        """Parse single sensor reading."""
        return {
            'sensor_id': data.get('sensor_id') or data.get('id'),
            'timestamp': data.get('timestamp') or data.get('time'),
            'value': data.get('value') or data.get('reading'),
            'unit': data.get('unit', ''),
            'location': data.get('location', '')
        }

    def parse_sensor_batch(self, data: List[Dict]) -> pd.DataFrame:
        """Parse batch of sensor readings."""
        readings = [self.parse_sensor_reading(r) for r in data]
        return pd.DataFrame(readings)

クイックスタート

parser = ConstructionJSONParser()

# Parse from file
result = parser.parse_file("bim_export.json")
if result.success:
    df = parser.to_dataframe(result.data)
    print(f"Loaded {len(df)} records")

# Flatten nested JSON
flat = parser.flatten_json(result.data)

# Extract specific path
elements = parser.extract_elements(result.data, "project.building.floors")

よくあるユースケース

1. BIM メタデータ

bim_parser = BIMJSONParser()
result = bim_parser.parse_file("revit_export.json")
elements = bim_parser.parse_bim_elements(result.data)

2. IoT センサー

iot_parser = IoTJSONParser()
readings = iot_parser.parse_sensor_batch(sensor_data)

3. API レスポンス

parser = ConstructionJSONParser()
result = parser.parse_string(api_response)
df = parser.to_dataframe(result.data)

リソース

• DDC Book：第 2.1 章 - 半構造化データ