Add support for downloading layers (#7)

Author: arredond

Diff for: felt_python/__init__.py

@@ -16,6 +16,8 @@
     refresh_url_layer,
     get_layer_details,
     update_layer_style,
+    get_export_link,
+    download_layer,
 )
 from .elements import (
     list_elements,
@@ -50,6 +52,8 @@
     "refresh_url_layer",
     "get_layer_details",
     "update_layer_style",
+    "get_export_link",
+    "download_layer",
     "AuthError",
     "list_elements",
     "list_element_groups",

Diff for: felt_python/layers.py

@@ -19,6 +19,7 @@
 REFRESH_TEMPLATE = urljoin(LAYER_TEMPLATE, "refresh")
 UPDATE_STYLE_TEMPLATE = urljoin(LAYER_TEMPLATE, "update_style")
 UPLOAD_TEMPLATE = urljoin(MAP_TEMPLATE, "upload")
+EXPORT_TEMPLATE = urljoin(LAYER_TEMPLATE, "get_export_link")
 
 
 def list_layers(map_id: str, api_token: str | None = None):
@@ -209,3 +210,45 @@ def update_layer_style(
         api_token=api_token,
     )
     return json.load(response)
+
+
+def get_export_link(
+    map_id: str,
+    layer_id: str,
+    api_token: str | None = None,
+):
+    """Get a download link for a layer
+
+    Vector layers will be downloaded in GPKG format. Raster layers will be GeoTIFFs.
+    """
+    response = make_request(
+        url=EXPORT_TEMPLATE.format(
+            map_id=map_id,
+            layer_id=layer_id,
+        ),
+        method="GET",
+        api_token=api_token,
+    )
+    return json.load(response)["export_link"]
+
+
+def download_layer(
+    map_id: str,
+    layer_id: str,
+    file_name: str | None = None,
+    api_token: str | None = None,
+) -> str:
+    """Download a layer to a file.
+
+    Vector layers will be downloaded in GPKG format. Raster layers will be GeoTIFFs.
+    If a specific file name is not provided, the default file name will be saved to
+    the current working directory.
+    """
+    export_link = get_export_link(map_id, layer_id, api_token)
+    with urllib.request.urlopen(export_link) as response:
+        if file_name is None:
+            parsed_url = urllib.parse.urlparse(response.url)
+            file_name = os.path.basename(parsed_url.path)
+        with open(file_name, "wb") as file_obj:
+            file_obj.write(response.read())
+    return file_name

Diff for: testing_layers.ipynb

@@ -286,6 +286,28 @@
     "list_layers(map_id)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "6cc3e80a",
+   "metadata": {},
+   "source": [
+    "# Downloading a layer\n",
+    "\n",
+    "Download the file uploaded layer as a GeoPackage"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "eb3a3b0f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from felt_python import download_layer\n",
+    "\n",
+    "download_layer(map_id, layer_id, file_name=\"exported.gpkg\")"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "e3574d06-bfbd-46bc-a86e-b70be7167cbf",
@@ -321,7 +343,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.11.6"
+   "version": "3.12.3"
   }
  },
  "nbformat": 4,