Fix memory leaks, add docs, and address comments

Signed-off-by: Arham Chopra <[email protected]>

cpp/csp/python/PyStructToJson.cpp

@@ -198,35 +198,37 @@ rapidjson::Value toJsonRecursive( const StructPtr& self, rapidjson::Document& do
     return new_dict;
 }
 
-std::pair<const char *, Py_ssize_t> pyObjectToString( PyObject * py_obj )
-{
-    auto * str_obj = PyObject_Str( py_obj );
-    Py_ssize_t len = 0;
-    const char * str = PyUnicode_AsUTF8AndSize( str_obj, &len );
-    return std::make_pair( str, len );
-}
-
 rapidjson::Value pyDictKeyToName( PyObject * py_key, rapidjson::Document& doc, PyObject * callable )
 {
     // NOTE: Only support None, bool, strings, ints, and floats, date, time, datetime, enums, csp.Enums as keys
     // JSON encoding requires all names to be strings so convert them to strings
 
     static thread_local PyTypeObjectPtr s_tl_enum_type;
     // Get the enum type on the first call and save it for future use
-    if( s_tl_enum_type.get() == nullptr )
+    if( s_tl_enum_type.get() == nullptr ) [[unlikely]]
     {
         // Import enum module to extract the Enum type
         auto py_enum_module = PyObjectPtr::own( PyImport_ImportModule( "enum" ) );
         if( py_enum_module.get() )
         {
             s_tl_enum_type = PyTypeObjectPtr::own( reinterpret_cast<PyTypeObject*>( PyObject_GetAttrString( py_enum_module.get(), "Enum" ) ) );
         }
+        else
+        {
+            CSP_THROW( RuntimeException, "Unable to import enum module from the python standard library" );
+        }
     }
 
     rapidjson::Value val;
-    if( ( py_key == Py_None ) || ( PyBool_Check( py_key ) ) )
+    if( py_key == Py_None )
+    {
+        val.SetString( "null" );
+    }
+    else if( PyBool_Check( py_key ) )
     {
-        auto[str, len] = pyObjectToString( py_key );
+        auto str_obj = PyObjectPtr::own( PyObject_Str( py_key ) );
+        Py_ssize_t len = 0;
+        const char * str = PyUnicode_AsUTF8AndSize( str_obj.get(), &len );
         val.SetString( str, len, doc.GetAllocator() );
     }
     else if( PyUnicode_Check( py_key ) )
@@ -246,7 +248,8 @@ rapidjson::Value pyDictKeyToName( PyObject * py_key, rapidjson::Document& doc, P
         auto json_obj = doubleToJson( key, doc );
         if ( json_obj.IsNull() )
         {
-            auto[str, len] = pyObjectToString( py_key );
+            auto str_obj = PyObjectPtr::own( PyObject_Str( py_key ) );
+            const char * str = PyUnicode_AsUTF8( str_obj.get() );
             CSP_THROW( ValueError, "Cannot serialize " + std::string( str ) + " to key in JSON" );
         }
         else
@@ -279,8 +282,11 @@ rapidjson::Value pyDictKeyToName( PyObject * py_key, rapidjson::Document& doc, P
     }
     else if( PyType_IsSubtype( Py_TYPE( py_key ), s_tl_enum_type.get() ) )
     {
-        auto enum_name = PyObjectPtr::own( PyObject_GetAttrString( py_key, "name" ) );
-        auto[str, len] = pyObjectToString( enum_name.get() );
+        // Use the `name` attribute of the enum for the string representation
+        auto py_enum_name = PyObjectPtr::own( PyObject_GetAttrString( py_key, "name" ) );
+        auto str_obj = PyObjectPtr::own( PyObject_Str( py_enum_name.get() ) );
+        Py_ssize_t len = 0;
+        const char * str = PyUnicode_AsUTF8AndSize( str_obj.get(), &len );
         val.SetString( str, len, doc.GetAllocator() );
     }
     else

csp/tests/impl/test_struct.py

@@ -1755,7 +1755,7 @@ class MyStruct(csp.Struct):
         d_none = {
             None: 2,
         }
-        d_none_res = {str(k): v for k, v in d_none.items()}
+        d_none_res = {"null": 2}
         test_struct = MyStruct(i=456, d_any=d_none)
         result_dict = {"i": 456, "d_any": d_none_res}
         self.assertEqual(json.loads(test_struct.to_json()), result_dict)

docs/wiki/api-references/csp.Struct-API.md

@@ -142,6 +142,7 @@ print(f"Using FastList field: value {s.a}, type {type(s.a)}, is Python list: {is
 - **`from_dict(self, dict)`**: convert a regular python dict to an instance of the struct
 - **`metadata(self)`**: returns the struct's metadata as a dictionary of key : type pairs
 - **`to_dict(self)`**: convert struct instance to a python dictionary
+- **`to_json(self, callback=lamda x: x)`**: convert struct instance to a json string, callback is invoked for any values encountered when processing the struct that are not basic python types, datetime types, tuples, lists, dicts, csp.Structs, or csp.Enums. The callback should convert the unhandled type to a combination of the known types.
 - **`all_fields_set(self)`**: returns `True` if all the fields on the struct are set. Note that this will not recursively check sub-struct fields
 
 # Note on inheritance