More clear documentation about the use of relative filter patterns on bcdc_promise class

[paulinamarczak]

I was getting an odd "cannot connect to wfs" error when I made a query that included a grepl filter statement.

It seems that bcdata does not accept grepl

vri_test <-  bcdc_query_geodata('2ebb35d8-c82f-4a17-9c96-612ac3532d55') %>% 
		select(
			POLYGON_AREA,
			BCLCS_LEVEL_4,
			REFERENCE_YEAR,
			INVENTORY_REGION,
			LINE_7B_DISTURBANCE_HISTORY,
			ORG_UNIT_CODE,
			REFERENCE_DATE,
			SPECIES_CD_1,
			SPECIES_PCT_1,
			WHOLE_STEM_BIOMASS_PER_HA) %>%
		filter(grepl("B"|"BE"), LINE_7B_DISTURBANCE_HISTORY) # DOES NOT WORK
                filter(LINE_7B_DISTURBANCE_HISTORY %LIKE% "B%") # works
		#collect() #return as sf object

The only cryptic error message that is returned if using the line with grepl is:

"Error: There was an issue sending this WFS request".

When i tried troubleshooting using str_starts(), I finally got an error message that helped me decode what I was doing wrong,

"Only fixed patterns are supported on database backends.".

Could you update the documentation to explain these constraints for filter types accepted for bcdc _promise class?

[ateucher]

Thanks @paulinamarczak - it would be good to update the documentation around partial string matching. If you're interested in contributing to that documentation, a pull request would be welcome!

For completeness, we have discussed this issue previously here: #227

[paulinamarczak]

I would contribute but I'm not that fluent in bcdata package (just started using today) and the extent of the issue, and what pages would all need to be updated. Hopefully seeing my solution to this issue helps someone though!

[bevingtona]

Would it be sufficient to add the example below to the bcdc_query_geodata {bcdata} description? I'm happy to make a pull request.

# To query based on partial matches, use %LIKE%:
try(
  bcdc_query_geodata("bc-airports") %>%
    filter(PHYSICAL_ADDRESS %LIKE% 'Vict%') 
)

Also, the use of %IN%

try(
  bcdc_query_geodata("bc-airports") %>%
    filter(AIRPORT_NAME %IN% c("Victoria Harbour (Camel Point) Heliport",
                               "Victoria Harbour (Shoal Point) Heliport")) %>% 
    collect()
)

[ateucher]

Yes please @bevingtona that would be awesome!

[stephhazlitt]

@paulinamarczak adding some text and an example in the Querying Spatial Data with bcdata vignette would be a great (first) contribution to bcdata, maybe added something about partial matching would work here?

[paulinamarczak]

hi Stephanie. I will try to add to the vignette during some downtime (put it on my task board). Thank you for your helpful directions.