Feature: Output as geojson Feature Collection (#86)

* Add support for geojson output

* Fix failed tests

* Change to correct geojson syntax

* formatting

* documentation geojson

* Fix lon lat order

---------

Co-authored-by: arnsetzer <[email protected]>
Co-authored-by: Andrew Nisbet <[email protected]>

Author: arnesetzer

docs/api.md

@@ -24,12 +24,15 @@ Latitudes and longitudes should be in `EPSG:4326` (also known as WGS-84 format),
     * The default option `null` makes NODATA indistinguishable from a location outside the dataset bounds. 
     * `NaN` (not a number) values aren't valid in json and will break some clients. The `nan` option was default before version 1.4 and is provided only for backwards compatibility. 
     * When querying multiple datasets, this NODATA replacement only applies to the last dataset in the stack.
+* `geojson`: If set to `True` the response will be in geojson according to RFC7946.
 
 
 
 
 ### Response
 
+#### Default
+
 A json object, compatible with the Google Maps Elevation API.
 
 * `status`: Will be `OK` for a successful request, `INVALID_REQUEST` for an input (4xx) error, and `SERVER_ERROR` for anything else (5xx). Required.
@@ -46,8 +49,21 @@ Some notes about the elevation value:
 * If the request location isn't covered by any raster in the dataset, Open Topo Data will return `null`.
 * Unless the `nodata_value` parameter is set, a `null` elevation could either mean the location is outside the dataset bounds, or a NODATA within the raster bounds. 
 
+#### Geojson
 
+A json object, fulfilling the RFC 7946 or an error message
+* `type`: FeatureCollection
+* `features`: An array of provided points
+    * `type`: Feature
+    * `geometry`
+        * `type`: Point
+        * `coordinates`: Longitude, latitude and Elevation
+    * `properties`
+        * `dataset`: Name of the dataset
 
+In case of an error:
+* `status`: Will be `OK` for a successful request, `INVALID_REQUEST` for an input (4xx) error, and `SERVER_ERROR` for anything else (5xx). Required.
+* `error`: Description of what went wrong, when `status` isn't `OK`.
 ### Example
 
 `GET` <a href="https://api.opentopodata.org/v1/srtm90m?locations=-43.5,172.5|27.6,1.98&interpolation=cubic">api.opentopodata.org/v1/srtm90m?locations=-43.5,172.5|27.6,1.98&interpolation=cubic</a>
@@ -79,6 +95,48 @@ Some notes about the elevation value:
 }
 ```
 
+#### With geojson
+
+`GET` <a href="https://api.opentopodata.org/v1/srtm90m?locations=-43.5,172.5|27.6,1.98&interpolation=cubic&geojson=True">api.opentopodata.org/v1/srtm90m?locations=-43.5,172.5|27.6,1.98&interpolation=cubic&geojson=True</a>
+
+
+
+
+```json
+{
+  "features": [
+    {
+      "geometry": {
+        "coordinates": [
+          172.5,
+          -43.5,
+          45
+        ],
+        "type": "Point"
+      },
+      "properties": {
+        "dataset": "srtm90m"
+      },
+      "type": "Feature"
+    },
+    {
+      "geometry": {
+        "coordinates": [
+          1.98,
+          27.6,
+          402
+        ],
+        "type": "Point"
+      },
+      "properties": {
+        "dataset": "srtm90m"
+      },
+      "type": "Feature"
+    }
+  ],
+  "type": "FeatureCollection"
+}
+```
 ---
 
 

opentopodata/api.py

@@ -19,6 +19,7 @@
 LON_MIN = -180
 LON_MAX = 180
 VERSION_PATH = "VERSION"
+DEFAULT_GEOJSON_VALUE = False
 
 
 # Memcache is used to store the latlon -> filename lookups, which can take a
@@ -524,6 +525,10 @@ def get_elevation(dataset_name):
             _find_request_argument(request, "locations"),
             _load_config()["max_locations_per_request"],
         )
+        try:
+            geojson = _find_request_argument(request, "geojson")
+        except:
+            geojson = DEFAULT_GEOJSON_VALUE
 
         # Check if need to do sampling.
         n_samples = _parse_n_samples(
@@ -541,15 +546,27 @@ def get_elevation(dataset_name):
 
         # Build response.
         results = []
-        for z, dataset_name, lat, lon in zip(elevations, dataset_names, lats, lons):
-            results.append(
-                {
-                    "elevation": z,
-                    "dataset": dataset_name,
-                    "location": {"lat": lat, "lng": lon},
-                }
-            )
-        data = {"status": "OK", "results": results}
+        # Return the results in geojson format. Default false to keep API consistancy
+        if geojson:
+            for z, dataset_name, lat, lon in zip(elevations, dataset_names, lats, lons):
+                results.append(
+                    {
+                        "type": "Feature",
+                        "geometry": {"type": "Point", "coordinates": [lon, lat, z]},
+                        "properties": {"dataset": dataset_name},
+                    },
+                )
+            data = {"type": "FeatureCollection", "features": results}
+        else:
+            for z, dataset_name, lat, lon in zip(elevations, dataset_names, lats, lons):
+                results.append(
+                    {
+                        "elevation": z,
+                        "dataset": dataset_name,
+                        "location": {"lat": lat, "lng": lon},
+                    }
+                )
+            data = {"status": "OK", "results": results}
         return jsonify(data)
 
     except (ClientError, backend.InputError) as e: