As of now the available providers supported for CQL filtering are limited to Elasticsearch <Elasticsearch>
and PostgreSQL <PostgreSQL>
.
Support of CQL is limited to Simple CQL filter and thus it allows to query with the following predicates:
- comparison predicates
- spatial predicates
- temporal predicates
At the moment Elasticsearch supports only the CQL dialect with the JSON encoding CQL-JSON.
PostgreSQL supports both CQL-JSON and CQL-text dialects, CQL-JSON and CQL-TEXT
The PostgreSQL provider uses pygeofilter allowing a range of filter expressions, see examples for:
Using Elasticsearch the following type of queries are supported right now:
between
predicate query- Logical
and
query withbetween
andeq
expression - Spatial query with
bbox
Note that when using a spatial operator in your filter expression, geometries are by default interpreted as being in the OGC:CRS84 Coordinate Reference System. If you wish to provide geometries in other CRS, use the filter-crs
query parameter with a suitable value.
Alternatively, a geometry's CRS may also be included using Extended Well-Known Text, in which case it will override the value of filter-crs
(if any) - this can be useful if your filtering expression is complex enough to need multiple geometries expressed in different CRSs. The standard way of providing filter-crs
as an additional query parameter is preferable for most cases.
A BETWEEN
example for a specific property through an HTTP POST request:
curl --location --request POST 'http://localhost:5000/collections/nhsl_hazard_threat_all_indicators_s_bc/items?f=json&limit=50&filter-lang=cql-json' \
--header 'Content-Type: application/query-cql-json' \
--data-raw '{
"between": {
"value": { "property": "properties.MHn_Intensity" },
"lower": 0.59,
"upper": 0.60
}
}'
Or
curl --location --request POST 'http://localhost:5000/collections/recentearthquakes/items?f=json&limit=10&filter-lang=cql-json'
--header 'Content-Type: application/query-cql-json'
--data-raw '{
"between":{
"value":{"property": "ml"},
"lower":4,
"upper":4.5
}
}'
The same BETWEEN
query using HTTP GET request formatted as CQL text and URL encoded as below:
curl "http://localhost:5000/collections/recentearthquakes/items?f=json&limit=10&filter=ml%20BETWEEN%204%20AND%204.5"
An EQUALS
example for a specific property:
curl --location --request POST 'http://localhost:5000/collections/recentearthquakes/items?f=json&limit=10&filter-lang=cql-json'
--header 'Content-Type: application/query-cql-json'
--data-raw '{
"eq":[{"property": "user_entered"},"APBE"]
}'
A CROSSES
example via an HTTP GET request. The CQL text is passed via the filter
parameter.
curl "http://localhost:5000/collections/hot_osm_waterways/items?f=json&filter=CROSSES(foo_geom,%20LINESTRING(28%20-2,%2030%20-4))"
A DWITHIN
example via HTTP GET and using a custom CRS for the filter geometry:
curl "http://localhost:5000/collections/beni/items?filter=DWITHIN(geometry,POINT(1392921%205145517),100,meters)&filter-crs=http://www.opengis.net/def/crs/EPSG/0/3857"
The same example, but this time providing a geometry in EWKT format:
curl "http://localhost:5000/collections/beni/items?filter=DWITHIN(geometry,SRID=3857;POINT(1392921%205145517),100,meters)"
Note that the CQL text has been URL encoded. This is required in curl commands but when entering in a browser, plain text can be used e.g. CROSSES(foo_geom, LINESTRING(28 -2, 30 -4))
.