How to prevent "Type error: unhashable type" while writing properties with Fiona?

Question

Using shapely's dissolve method I created new geometries from two existing shapefiles. Now I would like to save those new geometries and their properties with Fiona.

I have tried to write the properties in Dict as well as OrderdDict format, but still keep receiving Type error: unhashable type: 'Dict' or Type error: unhashable type: 'collections.OrderedDict'.

I consulted several sources, including:

• Using Fiona to write a new shapefile from scratch
• Fiona - Preffered method for defining a schema
• Fiona Manual: https://fiona.readthedocs.io/en/latest/manual.html

1 Data structure

for poly_element in difference_geometry:
    diff_feature = {
        "geometry" : {
            'type': 'Polygon',
            'coordinates': poly_element,
            },

1a - OrderedDict

        # ordered dictionary
        "properties" : OrderedDict([
            ("area_code", difference_area_code),
            ("area_name", difference_area_name),
            ("area_type", difference_area_type),
            ]),
        }

    shapely_geometries.append(diff_feature)

1b - Dict

        # dictionary
        "properties" : {
            "area_code" : difference_area_code,
            "area_name" : difference_area_name,
            "area_type" : difference_area_type,
            },

    shapely_geometries.append(diff_feature)

2 Output parameters

stat_area_crs = from_epsg(28992)
output_driver = "ESRI Shapefile"

2a - OrderedDict

stat_area_schema = {
    'geometry' : 'Polygon',
    'properties' : OrderedDict([
        ('area_code', 'str'),
        ('area_name', 'str'),
        ('area_type', 'str')
    ])
}

2b - Dict

stat_area_schema = {
    'geometry' : 'Polygon',
    'properties' : {
        'area_code' : 'str',
        'area_name' : 'int',
        'area_type' : 'str'
    }
}

3 Write output to shapefile

with fiona.open(
        'new_stat_areas.shp',
        'w',
        driver = output_driver,
        crs = stat_area_crs,
        schema = stat_area_schema) as c:
    for feature in shapely_geometries:
        c.write({
            'geometry': mapping(feature['geometry']['coordinates']),
            'properties': {feature['properties']}
        })

4 Error message

4a - OrderedDict:

Traceback (most recent call last):
  File "dataIntersections.py", line 191, in <module>
    'properties': {feature['properties']}
TypeError: unhashable type: 'collections.OrderedDict

4b - Dict:

Traceback (most recent call last):
  File "dataIntersections.py", line 190, in <module>
    'properties': {feature['properties']}
TypeError: unhashable type: 'dict'

5 Extra info

When replacing the c.write part for this print statement:

pprint.pprint({'geometry': mapping(feature['geometry']['coordinates']),
      'properties': feature['properties']})

The script returns this (cropped) information:

5a - OrderedDict

{'geometry': {'coordinates': (((144200.28399658203, 460830.77520751953),
                               # (...)
                               (150070.26199916803, 454926.5999999999),
                               (150039.87305716722, 454945.22763747524))),
              'type': 'Polygon'},
 'properties': OrderedDict([('area_code', 'GM0355'),
                            ('area_name', 'Zeist'),
                            ('area_type', 'Rural')])}

5b - Dict

{'geometry': {'coordinates': (((153474.06604003906, 469029.67779541016),
                              # (...)
                               (153473.87103271484, 469029.7180175781),
                               (153474.06604003906, 469029.67779541016)),),
              'type': 'Polygon'},
 'properties': {'area_code': 'GM0307',
                'area_name': 'Amersfoort',
                'area_type': 'Rural'}}

I would like to know what goes wrong and how to solve it!