POST CQL filter (with large geometry) in HTTP body

Question

The size of an URL is limited. Therefore I'm not able to request a WFS with a complex geometry. I read (Geoserver POST filter to WMS layer) that is possible to do in a WMS, but I didn't get it to work.

I'm using Postman to POST to my geoserver and add raw body data like this:

CQL_FILTER=INTERSECTS(geometry, POLYGON ((0 0, 1 1....))

I also tried it in key-value form type. I also tried url-encoding it first.

Does anyone know how to query with large geometries? (WKT in my case).

Answer 1

Complete post request would be

var url = 'http://localhost/geoserver/ows?service=WFS&version=1.0.0&outputFormat=application%2Fjson&request=GetFeature&typeName=topp:states',
    wktRepresentation = 'POLYGON((579832.0820867891 165971.37415659515,579946.6092781681 165790.03943691167,580180.4356272336 165914.11056090562,580149.4178462351 166047.7256175145,579832.0820867891 165971.37415659515))';

$.post(url, { cql_filter: 'INTERSECTS(geom, ' + wktRepresenation + ')' }, function(data, textStatus, xhr) {
    console.log(data);
});

Coordinates are in different projection for my example but just change them with coordinate system which you are using.

Answer 2

I already found an answer myself: I had to use x-www-form-urlencoded key-value data.

Answer 3

The body of an http request can be coded in three ways :

• Can be one of form (application/x-www-form-urlencoded) ;
• multipart :multipart/form-data) ;
• or json (application/json).

For long cql_filter in geoserver, form body is used. An example below for R users with IGN WFS geoserver

library(httr2) # perform http request
library(sf) # work with spatial features

apikey <- "administratif"
layer_name <- "LIMITES_ADMINISTRATIVES_EXPRESS.LATEST:commune"

# Param for creating url
params <- list(
   service = "WFS",
   version = "2.0.0",
   request = "GetFeature",
   outputFormat = "json",
   srsName = "EPSG:4326",
   typeName = layer_name
)

filter <- "INTERSECTS(the_geom, POLYGON ((47.94371 -4.315395, 47.80732 -4.309902, 47.8774 -4.103909, 47.94739 -3.939114, 48.18246 -3.9501, 48.01729 -4.27969, 47.94371 -4.315395)))"

# construct request
request <- request("https://wxs.ign.fr") |>
   req_url_path_append(apikey) |>
   req_url_path_append("geoportail/wfs") |>
   req_url_query(!!!params) |> 
   req_body_form(cql_filter=filter)

# perform request
resp <- req_perform(request) |>
   resp_body_string()

# read features
features <- read_sf(resp)