From a762245d865f4e17ffc3a0d00e9519b4647e70d5 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Thu, 24 Oct 2024 18:24:03 +0100
Subject: [PATCH] elevation is optional in gpx

(so is nearly everything else, but am doing one thing at a time)
---
 src/Track.elm       |  4 ++--
 tests/Fixtures.elm  |  7 ++++---
 tests/TrackTest.elm | 14 ++++++++++++++
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/Track.elm b/src/Track.elm
index 708ef0d..5857671 100644
--- a/src/Track.elm
+++ b/src/Track.elm
@@ -8,7 +8,7 @@ import Iso8601
 type alias Point =
     { lat : Float
     , lon : Float
-    , ele : Float
+    , ele : Maybe Float
     , time : Time.Posix
     }
 
@@ -25,7 +25,7 @@ timeDecoder = XD.andThen (\ts ->
 pointDecoder = XD.map4 Point
                (floatAttr "lat")
                (floatAttr "lon")
-               (path ["ele"] (single XD.float))
+               (XD.maybe (path ["ele"] (single XD.float)))
                (path ["time"] (single timeDecoder))
 
 
diff --git a/tests/Fixtures.elm b/tests/Fixtures.elm
index 84b537d..6ce2d6c 100644
--- a/tests/Fixtures.elm
+++ b/tests/Fixtures.elm
@@ -1,6 +1,7 @@
 module Fixtures exposing (threepoints, threepoints_expected)
 import Track exposing (Track, Point)
 import Time
+import Maybe
 
 
 threepoints = """
@@ -64,7 +65,7 @@ xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/
 """
 
 threepoints_expected  =
-    [ (Point 51.600643 -0.01856  64.8 (Time.millisToPosix 1729669252256))
-    , (Point 51.600679 -0.018179  65.5 (Time.millisToPosix 1729669255259))
-    , (Point 51.600697 -0.018064 66.2 (Time.millisToPosix 1729669256231))
+    [ (Point 51.600643 -0.01856 (Just 64.8) (Time.millisToPosix 1729669252256))
+    , (Point 51.600679 -0.018179  (Just 65.5) (Time.millisToPosix 1729669255259))
+    , (Point 51.600697 -0.018064 (Just 66.2) (Time.millisToPosix 1729669256231))
     ]
diff --git a/tests/TrackTest.elm b/tests/TrackTest.elm
index 6135e54..dc86e67 100644
--- a/tests/TrackTest.elm
+++ b/tests/TrackTest.elm
@@ -4,6 +4,7 @@ import Fixtures
 import Track exposing (Track, Point)
 import Test exposing (..)
 import Expect exposing (Expectation)
+import Time
 
 specs: Test
 specs =
@@ -13,6 +14,19 @@ specs =
               case Track.parse Fixtures.threepoints of
                   (Ok trk) -> Expect.equalLists Fixtures.threepoints_expected trk
                   _ -> Expect.fail "not ok"
+        , test "missing child ele node in track point" <|
+              \_ ->
+              let
+                  xml = String.replace
+                        "<ele>64.8</ele>"
+                        ""
+                        Fixtures.threepoints
+              in
+                  case Track.parse xml of
+                      Ok (p::pts) -> Expect.equal p (Point 51.600643 -0.01856 Nothing (Time.millisToPosix 1729669252256))
+                      Ok _ -> Expect.fail "empty list"
+                      (Err f) -> Expect.fail f
+
         , test "multiple trksegs are coalesced" <|
               \_ ->
               let