How to ensure the values set in the CSV are captured within the GeoJSON feature values when merging CSV attributes into a GeoJSON

Question

I create a GeoJSON but the merged values are null. The length of the datasets do not match -- is this a potential issue? If so, how do I merge for all covid matches. (FYI this isnt Covid19 related COV is short for covenant- housing).

I have tried the method suggested here. https://gis.stackexchange.com/a/359055/177082

import pandas
import geopandas
import fiona

gdf = geopandas.read_file(r'.\\UL1.geojson') # geojson file
df = pandas.read_csv(r'D:\ATMS\data\Blank.csv') #CSVfile

hvista=gdf.merge(df, on='Covid', how='left')


hvista.to_file("Hvista.geojson", driver="GeoJSON")

print(hvista)

and assuming it is a data type issue i have tried the following:

    import pandas
import geopandas 
import shapely
from geopandas import GeoDataFrame

gdf = geopandas.read_file(r'.\\UL1.geojson') # geojson file
df = pandas.read_csv(r'.\data\Blank.csv') #CSVfile



gdfa=gdf.merge(df.astype(str), on='Covid', how='left')
gdfa=GeoDataFrame(gdfa, crs="urn:ogc:def:crs:EPSG::3857")
gdfa.to_file("Hvista.geojson", driver="GeoJSON")

print(gdfa)

Answer 1

yikes, so the above is fine. the code was throwing "NaN" due to inconsistencies (capitalisation) in the 'covid' field in df. Sorry if I have wasted anyone's time.