admin.py

class LeafletJSONField(JSONField):
    widget = LeafletWidget(width='100%', height='400px')

    def process_formdata(self, valuelist):
        if valuelist:
            value = valuelist[0]
            if not value:
                self.data = None
                return
            try:
                self.from_json(value)
                self.data = value
            except ValueError:
                self.data = None

    def _value(self):
        if self.raw_data:
            return self.raw_data[0]
        if self.data:
            return self.data
        return ""
 
class OrganizationView(ModelView):
     form_overrides['polygon'] = LeafletJSONField

template.html

{% block tail %}
    {{ super() }}
    <script src="https://api.mapbox.com/mapbox.js/v2.2.1/mapbox.js"></script>
    <script type='text/javascript'>
     L.mapbox.accessToken = 'pk.eyJ1IjoibWFwYm94IiwiYSI6IlpIdEpjOHcifQ.Cldl4wq_T5KOgxhLvbjE-w';
    </script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet.draw/0.2.3/leaflet.draw.js"></script>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/leaflet.draw/0.2.3/leaflet.draw.css">
    <script type="text/javascript">
        L.Map.addInitHook(function () {
             this.addControl(L.mapbox.geocoderControl('mapbox.places'));

             var streetLayer = L.mapbox.tileLayer('KEY').addTo(this);
             var satelliteLayer = L.mapbox.tileLayer('KEY').addTo(this);

            var baseMaps = {
                "Satellite": satelliteLayer,
                "Rue": streetLayer
            };

             L.control.layers(baseMaps).addTo(this);

             this.setView([48.55, -3.15], 10);
        });
    </script>
{% endblock %}