Fix: flatten objects with same name, unorderable fields

Bug reported by Mantas. If a resource (or its prototype) has two
fields with the same name, but unorderable value types (such as string
and integer), the flatten_object function used to crash. This is now
fixed.

4 files changed, 24 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index 8153469..9b7d8fe 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,11 @@ Bug fixes:
   resources, not just `foo`. This has been fixed. Bug reported by
   Kaius, fixed by Lars.
 
+* Mantas reported that if a resource type or resource had two fields
+  with the same type but values that were not possible to compare,
+  such as a string and an integer, Qvarn would crash. This is now
+  fixed.
+
 Version 0.86, released 2017-10-10
 ----------------------------------
 
diff --git a/qvarn/objstore.py b/qvarn/objstore.py
index 90d4e84..d88774e 100644
--- a/qvarn/objstore.py
+++ b/qvarn/objstore.py
@@ -386,7 +386,18 @@ class NoSuchObject(Exception):
 
 
 def flatten_object(obj):
-    return list(sorted(set(_flatten(obj))))
+    # We sort only by the name, not the object in each pair in the
+    # list. Otherwise, if there are two fields with the same name but
+    # incompatible value types this will break. However, to guarantee
+    # that objects always result in the same flattened representation,
+    # we also compare the second field. For this, we convert the
+    # second value to a string with repr. This allows the second
+    # fields to be compared regardless of type.
+
+    pairs = _flatten(obj)
+    unique_pairs = set(pairs)
+    sorted_pairs = sorted(unique_pairs, key=repr)
+    return list(sorted_pairs)
 
 
 def _flatten(obj, obj_key=None):
diff --git a/qvarn/resource_type_tests.py b/qvarn/resource_type_tests.py
index a1fd09a..36c775b 100644
--- a/qvarn/resource_type_tests.py
+++ b/qvarn/resource_type_tests.py
@@ -59,6 +59,7 @@ class ResourceTypeTests(unittest.TestCase):
                     'prototype': {
                         'foo': '',
                         'bar': '',
+                        'version': 0,  # test for bug
                     },
                     'subpaths': {
                         'subfoo': {
diff --git a/resource_type/files.yaml b/resource_type/files.yaml
index 947b7f6..ef74217 100644
--- a/resource_type/files.yaml
+++ b/resource_type/files.yaml
@@ -4,7 +4,12 @@ versions:
 - prototype: {id: '', revision: '', type: ''}
   version: v0
 - files: [file]
-  prototype: {filename: '', id: '', revision: '', type: ''}
+  prototype:
+    filename: ''
+    id: ''
+    revision: ''
+    type: ''
+    version: 0
   subpaths:
     file:
       prototype: {body: blob, content_type: ''}