LOD attributes all have string data types

[ymoisan]

Here's a cityjson file excerpt

 "lod": "2.2",
          "semantics": {
            "surfaces": [
...
              {
                "rf_azimuth": 244.7989501953125,
                "rf_roof_elevation_50p": 165.9402618408203,
                "rf_roof_elevation_70p": 166.33753967285156,
                "rf_roof_elevation_max": 166.9029083251953,
                "rf_roof_elevation_min": 164.65676879882812,
                "rf_slope": 29.86277198791504,
                "type": "RoofSurface"
              },
...

The current implementation of the plugin will import all of those as strings even though all but one are not.

I tried this implementation

class SemanticSurfaceFieldsDecorator:
    """A class that creates an LoD field"""

    def __init__(self, decorated, citymodel):
        self._decorated = decorated
        self._citymodel = citymodel
        self._attribute_types = self._get_attribute_types()

    def _get_qgis_type(self, value):
        if isinstance(value, bool):
            return QVariant.Bool
        elif isinstance(value, int):
            return QVariant.Int
        elif isinstance(value, float):
            return QVariant.Double
        else:
            return QVariant.String

    def _get_attribute_types(self):
        attribute_types = {}
        for obj in self._citymodel["CityObjects"].values():
            if "geometry" in obj:
                for geom in obj["geometry"]:
                    if "semantics" in geom:
                        for surface in geom["semantics"]["surfaces"]:
                            for att_key, att_value in surface.items():
                                qtype = self._get_qgis_type(att_value)
                                if att_key not in attribute_types or (qtype == QVariant.Double and attribute_types[att_key] != QVariant.Double) or (qtype == QVariant.String and attribute_types[att_key] != QVariant.String):
                                    attribute_types[att_key] = qtype
                                elif qtype == QVariant.Int and attribute_types[att_key] == QVariant.Bool:
                                     attribute_types[att_key] = qtype

        return attribute_types

And it solved the issue. See below (after modification at top)

I wonder if there would be a cleaner way to do it ?