better error handling for convert.smart_convert

Returning None is pretty nondescript, so let's make it official that we
raise an exception there.

3 files changed, 22 insertions, 6 deletions

diff --git a/fietsboek/convert.py b/fietsboek/convert.py
index 9cd3297..de6314f 100644
--- a/fietsboek/convert.py
+++ b/fietsboek/convert.py
@@ -12,6 +12,17 @@ from .models import Track, Waypoint
 FIT_RECORD_FIELDS = ["position_lat", "position_long", "altitude", "timestamp"]
 
 
+class ConversionError(Exception):
+    """Error that occurred when loading a track from a file."""
+
+
+class UnknownFormat(ConversionError):
+    """The format of the source file could not be identified."""
+
+    def __str__(self):
+        return type(self).__doc__
+
+
 def semicircles_to_deg(circles: int) -> float:
     """Convert semicircles coordinate to degree coordinate.
 
@@ -30,6 +41,7 @@ def from_fit(data: bytes) -> Track:
 
     :param data: The input bytes.
     :return: The converted structure.
+    :raises ConversionError: If conversion failed.
     """
     fitfile = fitparse.FitFile(data)
     start_time = None
@@ -68,6 +80,7 @@ def from_gpx(data: bytes) -> Track:
 
     :param data: The input bytes.
     :return: The converted structure.
+    :raises ConversionError: If conversion failed.
     """
     # pylint: disable=too-many-locals
     gpx = gpxpy.parse(data)
@@ -132,7 +145,7 @@ def from_gpx(data: bytes) -> Track:
     return track
 
 
-def smart_convert(data: bytes) -> Optional[Track]:
+def smart_convert(data: bytes) -> Track:
     """Tries to be smart in converting the input bytes.
 
     This function automatically applies the correct conversion if possible.
@@ -142,12 +155,13 @@ def smart_convert(data: bytes) -> Optional[Track]:
 
     :param data: The input bytes.
     :return: The converted content.
+    :raises ConversionError: When conversion fails.
     """
     if len(data) > 11 and data[9:12] == b"FIT":
         return from_fit(data)
     if data.startswith(b"<?xml") and b"<gpx" in data[:200]:
         return from_gpx(data)
-    return None
+    raise UnknownFormat()
 
 
-__all__ = ["from_fit", "from_gpx", "smart_convert"]
+__all__ = ["ConversionError", "from_fit", "from_gpx", "smart_convert"]
diff --git a/fietsboek/models/track.py b/fietsboek/models/track.py
index c61c4e3..bd4bd15 100644
--- a/fietsboek/models/track.py
+++ b/fietsboek/models/track.py
@@ -395,7 +395,7 @@ class Track(Base):
         :return: The GPS path of this track.
         """
         return geo.Path(
-            [point.to_geo_point() for point in sorted(self.points, key=lambda p: p.index)]
+            [point.to_geo_point() for point in sorted(self.points, key=lambda p: p.index or 0.0)]
         )
 
     def gpx_xml(self) -> bytes:
diff --git a/fietsboek/views/edit.py b/fietsboek/views/edit.py
index 4e7b1f5..a40b8c2 100644
--- a/fietsboek/views/edit.py
+++ b/fietsboek/views/edit.py
@@ -92,9 +92,11 @@ def do_edit(request):
             pass
         else:
             LOGGER.info("Setting new track for %s", track.id)
-            new_track = convert.smart_convert(gpx_bytes)
-            if new_track is None:
+            try:
+                new_track = convert.smart_convert(gpx_bytes)
+            except convert.ConversionError as exc:
                 request.session.flash(request.localizer.translate(_("flash.invalid_file")))
+                LOGGER.info("Could not parse gpx: %s", exc)
                 return HTTPFound(request.route_url("edit", track_id=track.id))
             data.compress_backup(gpx_bytes)
             track.set_path(new_track.path())