how to remove coordinates from geojson with less then 4 values - sql

Question

as the title say, i am doing a query on a bikesharing data stored in bigquery
I am able to extract the data and arrange it in a correct order to be displayed in a path chart. In the data, there are coordinated with only start and end long and lat, or sometimes only start long and lat, how do i remove anything with less then 4 points?
this is the code , i am also limited to select only
SELECT
routeID ,
json_extract(st_asgeojson(st_makeline( array_agg(st_geogpoint(locs.lon, locs.lat) order by locs.date))),'$.coordinates') as geo
FROM
howardcounty.routebatches
where unlockedAt between {{start_date}} and {{end_date}}
cross join UNNEST(locations) as locs
GROUP BY routeID
order by routeID
limit 10
have also included a screen shot for clarity

Answer 1

To apply a condition after a group by, please use a having. For a simply condition -- Are there at least two dataset for the route? -- this query can be used:
With dummy as (
Select 1 as routeID, [struct(current_timestamp() as date, 1 as lon, 2 as lat),struct(current_timestamp() as date, 3 as lon, 4 as lat)] as locations
Union all select 2 as routeID, [struct(current_timestamp() as date, 10 as lon, 20 as lat)]
)
SELECT
routeID , count(locs.date) as amountcoord,
json_extract(st_asgeojson(st_makeline( array_agg(st_geogpoint(locs.lon, locs.lat) order by locs.date))),'$.coordinates') as geo
FROM
#howardcounty.routebatches
dummy
#where unlockedAt between {{start_date}} and {{end_date}}
cross join UNNEST(locations) as locs
GROUP BY routeID
having count(locs.date)>1
order by routeID
limit 10
For more complex ones, a nested select may do the job:
Select *
from (
--- your code ---
) where length(geo)-length(replace(geo,"]","")) > 1+4
The JSON is transformed to a string in your code. If you count the ] and substract one for the end of the JSON, the inside arrays are counted.