Example: Function to query Countries by Name
This is the same spatial function example shown in the Usage section. Here we’ll show a sample GeoJSON response and the web UI preview.
Note:
Another way to obtain this functionality is to use the filter query parameter with a LIKE CQl expression. See the CQL section
Create a spatial function that returns a filtered set of countries
CREATE OR REPLACE FUNCTION postgisftw.countries_name(
name_prefix text DEFAULT 'A')
RETURNS TABLE(name text, abbrev text, continent text, geom geometry)
AS $$
BEGIN
RETURN QUERY
SELECT t.name::text,
t.abbrev::text,
t.continent::text,
t.geom
FROM ne.admin_0_countries t
WHERE t.name ILIKE name_prefix || '%';
END;
$$
LANGUAGE 'plpgsql' STABLE PARALLEL SAFE;
COMMENT ON FUNCTION postgisftw.countries_name IS 'Filters the countries table by the initial letters of the name using the "name_prefix" parameter.';Example of API query
The function can be called via the API by providing a value for the name_prefix parameter.
http://localhost:9000/functions/countries_name/items?name_prefix=Mo
Since a default value is included in the function declaration, you could omit the parameter in the call – a random sample of features will be returned.
Sample GeoJSON response
The response is a GeoJSON document containing the 7 countries starting with the letters ‘Mo’.
{
"type":"FeatureCollection",
"features":[
{
"type":"Feature",
"geometry":{
"type":"MultiPolygon",
"coordinates":[
[
[
[
-62.1484375,
16.74033203125
],
[
-62.154248046875,
16.681201171875
],
...
[
-62.1484375,
16.74033203125
]
]
]
]
},
"properties":{
"abbrev":"Monts.",
"continent":"North America",
"name":"Montserrat"
}
},
...
],
"numberReturned":7,
"timeStamp":"2020-03-18T03:15:15Z",
"links":[
{
"href":"http://localhost:9000/collections/countries_name/items.json",
"rel":"self",
"type":"application/json",
"title":"This document as JSON"
},
{
"href":"http://localhost:9000/collections/countries_name/items.html",
"rel":"alternate",
"type":"text/html",
"title":"This document as HTML"
}
]
}Web preview
