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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Custom transformer - create_instance invoked incorrectly?","articleBody":"Hello!\r\n\r\nI'm trying to parse a file serializing an `ArrayList` of custom functions -- and I cannot even get the basics going...\r\n\r\nBelow is my entire script. Without the default value (such as `None`) for the `class_desc`, I get an error:\r\n```\r\n  File \"/home/mi/.local/lib/python3.9/site-packages/javaobj/v2/core.py\", line 528, in _do_object\r\n    instance = self._create_instance(class_desc)\r\n  File \"/home/mi/.local/lib/python3.9/site-packages/javaobj/v2/core.py\", line 503, in _create_instance\r\n    instance = transformer.create_instance(class_desc)\r\nTypeError: create_instance() missing 1 required positional argument: 'class_desc'\r\n```\r\n\r\nIf I put the default value, the call to `create_instance` goes through, and the method prints the value of `self`, which indicates, that it is the `class_desc` -- instead of referring to the transformer:\r\n```\r\nINFO:javaobj.parser:Reading next content\r\nDEBUG:javaobj.parser:Reading new object: handle 7e0001, classdesc [classdesc 0x7e0000: name java.util.ArrayList, uid 8683452581122892189]\r\nSelf is [classdesc 0x7e0000: name java.util.ArrayList, uid 8683452581122892189], class_desc is None\r\nTraceback ...\r\n```\r\n\r\nPlease, advise. Thank you!\r\n\r\n```python\r\nimport javaobj.v2 as javaobj\r\nimport sys\r\nimport os\r\nimport json\r\nimport pprint\r\nimport logging\r\n\r\nlogging.basicConfig(level = logging.DEBUG)\r\n\r\nclass odrnavsFunctionInstance(javaobj.beans.JavaInstance):\r\n\tdef __init__(self):\r\n\t\tjavaobj.beans.JavaInstance.__init__(self)\r\n\r\n\tdef load_from_instance(self):\r\n\t\tif not self.classdesc or self.classdesc not in self.field_data:\r\n\t\t\treturn False\r\n\r\n\t\tfields = self.classdesc.fields_names\r\n\t\tvalues = [\r\n\t\t\tself.field_data[self.classdesc][self.classdesc.fields[i]]\r\n\t\t\tfor i in range(len(fields))\r\n\t\t]\r\n\t\tself.field_data = dict(zip(fields, values))\r\n\t\tif not self.classdesc.super_class or \\\r\n\t\t    self.classdesc.super_class not in self.annotations:\r\n\t\t\treturn True\r\n\t\tsuper_class = self.annotations[self.classdesc.super_class][0]\r\n\t\tself.annotations = dict(zip(super_class.fields_names, super_class.field_data))\r\n\t\treturn True\r\n\r\nclass odrnavsTransformer(javaobj.transformers.ObjectTransformer):\r\n\r\n\tdef __init__(self, handled_classes = {\r\n\t\t'my.apps.datalayer.client.navs.shared.api.Function':\r\n\t\t    odrnavsFunctionInstance\r\n\t}):\r\n\t\tsuper(JavaRandomTransformer, self).__init__()\r\n\t\tself.instance = None\r\n\t\tself.handled_classes = handled_classes or {}\r\n\r\n\tdef create_instance(self, class_desc = None):\r\n\t\tprint('Self is %s, class_desc is %s' % (self, class_desc))\r\n\t\tif class_desc.name not in self.handled_classes:\r\n\t\t\treturn None\r\n\t\tself.instance = self.handled_classes[class_desc.name]()\r\n\t\treturn self.instance\r\n\r\nif sys.argv[1].endswith('.gz'):\r\n\timport gzip\r\n\topener = gzip.open\r\nelse:\r\n\topener = open\r\n\r\nobj = None\r\nwith opener(sys.argv[1], 'rb') as inp:\r\n\t\tobj = javaobj.load(inp, odrnavsTransformer)\r\n\r\npprint.pprint(obj)\r\n```\r\n","author":{"url":"https://github.com/UnitedMarsupials","@type":"Person","name":"UnitedMarsupials"},"datePublished":"2023-08-02T23:40:15.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/54/python-javaobj/issues/54"}