folium.features.GeoJson could give a more descriptive error when passing GeoDataFrames with missing geometries

I frequently pass GeoDataFrames to folium.features.GeoJson. When GeoDataFrames with missing geometries are passed, it gives ValueError: Unhandled object and then prints the table. It might be better if it said something more descriptive about how the GeoDataFrame was missing geometries.

This appears to be the relevant line. GeoDataFrames with missing geometries do not have the __geo_interface__ property. Not sure if this is something worth addressing in Folium or in GeoPandas.

Replicate error with

import geopandas as gpd
import folium as f

df = gpd.read_file(gpd.datasets.get_path('nybb'))
df.loc[0, 'geometry'] = None

f.features.GeoJson(df)

Output

ValueError: Unhandled object    BoroCode       BoroName     Shape_Leng    Shape_Area  \
0         5  Staten Island  330470.010332  1.623820e+09   
1         4         Queens  896344.047763  3.045213e+09   
2         3       Brooklyn  741080.523166  1.937479e+09   
3         1      Manhattan  359299.096471  6.364715e+08   
4         2          Bronx  464392.991824  1.186925e+09   

                                            geometry  
0                                               None  
1  (POLYGON ((1029606.076599121 156073.8142089844...  
2  (POLYGON ((1021176.479003906 151374.7969970703...  
3  (POLYGON ((981219.0557861328 188655.3157958984...  
4  (POLYGON ((1012821.805786133 229228.2645874023...  .

Output of folium.__version__

0.6.0

[ocefpaf]

How about silently stripping out the rows that have no geometries?

I’m not really sure that is a good idea. I’d rather leave data cleaning to the user than implicitly dropping empty rows. 99.99% of the cases an empty geometry row is indicative of another problem in the data.

[ocefpaf]

Okay, I’ll make a PR.

Thanks!