[python-experimental] Add support for pep 3134, attach cause of exception (#6388)

* Mustache template should use invokerPackage tag to generate import

* Add exception cause

* using six module for exception chaining in Python 3.x

Author: sebastien-rosset

modules/openapi-generator/src/main/resources/python/python-experimental/model_utils.mustache

@@ -725,14 +725,14 @@ def deserialize_primitive(data, klass, path_to_item):
                     # '7' -> 7.0 -> '7.0' != '7'
                     raise ValueError('This is not a float')
             return converted_value
-    except (OverflowError, ValueError):
+    except (OverflowError, ValueError) as ex:
         # parse can raise OverflowError
-        raise ApiValueError(
+        six.raise_from(ApiValueError(
             "{0}Failed to parse {1} as {2}".format(
                 additional_message, repr(data), get_py3_class_name(klass)
             ),
             path_to_item=path_to_item
-        )
+        ), ex)
 
 
 def get_discriminator_class(model_class,
@@ -1220,7 +1220,7 @@ def get_allof_instances(self, model_args, constant_args):
             allof_instance = allof_class(**kwargs)
             composed_instances.append(allof_instance)
         except Exception as ex:
-            raise ApiValueError(
+            six.raise_from(ApiValueError(
                 "Invalid inputs given to generate an instance of '%s'. The "
                 "input data was invalid for the allOf schema '%s' in the composed "
                 "schema '%s'. Error=%s" % (
@@ -1229,7 +1229,7 @@ def get_allof_instances(self, model_args, constant_args):
                     self.__class__.__name__,
                     str(ex)
                 )
-            )
+            ), ex)
     return composed_instances
 
 

samples/client/petstore/python-experimental/petstore_api/model_utils.py

@@ -992,14 +992,14 @@ def deserialize_primitive(data, klass, path_to_item):
                     # '7' -> 7.0 -> '7.0' != '7'
                     raise ValueError('This is not a float')
             return converted_value
-    except (OverflowError, ValueError):
+    except (OverflowError, ValueError) as ex:
         # parse can raise OverflowError
-        raise ApiValueError(
+        six.raise_from(ApiValueError(
             "{0}Failed to parse {1} as {2}".format(
                 additional_message, repr(data), get_py3_class_name(klass)
             ),
             path_to_item=path_to_item
-        )
+        ), ex)
 
 
 def get_discriminator_class(model_class,
@@ -1487,7 +1487,7 @@ def get_allof_instances(self, model_args, constant_args):
             allof_instance = allof_class(**kwargs)
             composed_instances.append(allof_instance)
         except Exception as ex:
-            raise ApiValueError(
+            six.raise_from(ApiValueError(
                 "Invalid inputs given to generate an instance of '%s'. The "
                 "input data was invalid for the allOf schema '%s' in the composed "
                 "schema '%s'. Error=%s" % (
@@ -1496,7 +1496,7 @@ def get_allof_instances(self, model_args, constant_args):
                     self.__class__.__name__,
                     str(ex)
                 )
-            )
+            ), ex)
     return composed_instances
 
 

samples/openapi3/client/petstore/python-experimental/petstore_api/model_utils.py

@@ -992,14 +992,14 @@ def deserialize_primitive(data, klass, path_to_item):
                     # '7' -> 7.0 -> '7.0' != '7'
                     raise ValueError('This is not a float')
             return converted_value
-    except (OverflowError, ValueError):
+    except (OverflowError, ValueError) as ex:
         # parse can raise OverflowError
-        raise ApiValueError(
+        six.raise_from(ApiValueError(
             "{0}Failed to parse {1} as {2}".format(
                 additional_message, repr(data), get_py3_class_name(klass)
             ),
             path_to_item=path_to_item
-        )
+        ), ex)
 
 
 def get_discriminator_class(model_class,
@@ -1487,7 +1487,7 @@ def get_allof_instances(self, model_args, constant_args):
             allof_instance = allof_class(**kwargs)
             composed_instances.append(allof_instance)
         except Exception as ex:
-            raise ApiValueError(
+            six.raise_from(ApiValueError(
                 "Invalid inputs given to generate an instance of '%s'. The "
                 "input data was invalid for the allOf schema '%s' in the composed "
                 "schema '%s'. Error=%s" % (
@@ -1496,7 +1496,7 @@ def get_allof_instances(self, model_args, constant_args):
                     self.__class__.__name__,
                     str(ex)
                 )
-            )
+            ), ex)
     return composed_instances