Can't use Dictionary<int, float> and .items() together #2379

AlanLiu90 · 2024-05-08T11:27:28Z

AlanLiu90
May 8, 2024

Environment

Pythonnet version: 3.0.3
Python version: 3.10
Operating System: Windows 10
.NET Runtime: net6.0

Details

Describe what you were trying to get done.

I passed a Dictionary<int, float> to a python function and wanted to call items() in it, but it threw an exception:

  Python.Runtime.PythonException : No method matches given arguments for Dictionary`2.TryGetValue: (<class 'int'>, <class 'NoneType'>)
    ----> System.ArgumentException : 'NoneType' value cannot be converted to System.Single in method Boolean TryGetValue(Int32, Single ByRef)
    ----> Python.Runtime.PythonException : 'NoneType' value cannot be converted to System.Single

Stack Trace: 
    File "<string>", line 52, in get
    File "<string>", line 48, in <listcomp>
    File "<string>", line 48, in items
    File "none", line 3, in foo
  PythonException.ThrowLastAsClrException() line 53
  NewReference.StealOrThrow() line 104
  PyObject.Invoke(PyTuple args, PyDict kw) line 801
  PyObject.InvokeMethod(String name, PyTuple args, PyDict kw) line 917
  PyObject.TryInvokeMember(InvokeMemberBinder binder, Object[] args, Object& result) line 1268
  CallSite.Target(Closure , CallSite , Object , Dictionary`2 )
  UpdateDelegates.UpdateAndExecuteVoid2[T0,T1](CallSite site, T0 arg0, T1 arg1)
  Codecs.ItemsTest() line 110
  --AggregateException
  --ArgumentException
  --PythonException

If I use Dictionary<int, object>, it works correctly.

What commands did you run to trigger this issue? If you can provide a
Minimal, Complete, and Verifiable example
this will help us understand the issue.

Run the following code in Python.EmbeddingTest project:

        [Test]
        public void ItemsTest()
        {
            var d = new Dictionary<int, float>();
            d.Add(0, 1.0f);
            d.Add(1, 2.0f);

            dynamic test = PyModule.FromString("items_test", @"
def foo(d):
    for k, v in d.items():
        print(k, v)
");

            test.foo(d);
        }

AlanLiu90 · 2024-05-08T20:54:48Z

AlanLiu90
May 8, 2024
Author

@filmor

Hi,

after some investigation, it seems this issue can be fixed by the the following modification:

 src/runtime/Converter.cs | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/runtime/Converter.cs b/src/runtime/Converter.cs
index 50b33e6..6022402 100644
--- a/src/runtime/Converter.cs
+++ b/src/runtime/Converter.cs
@@ -327,7 +327,7 @@ namespace Python.Runtime
                     throw new ArgumentException("We should never receive instances of other managed types");
             }
 
-            if (value == Runtime.PyNone && !obType.IsValueType)
+            if (value == Runtime.PyNone)
             {
                 result = null;
                 return true;
@@ -335,11 +335,6 @@ namespace Python.Runtime
 
             if (obType.IsGenericType && obType.GetGenericTypeDefinition() == typeof(Nullable<>))
             {
-                if (value == Runtime.PyNone)
-                {
-                    result = null;
-                    return true;
-                }
                 // Set type to underlying type
                 obType = obType.GetGenericArguments()[0];
             }

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Can't use Dictionary<int, float> and .items() together #2379

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AlanLiu90 May 8, 2024

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AlanLiu90 May 8, 2024 Author

AlanLiu90
May 8, 2024

AlanLiu90
May 8, 2024
Author