I'm trying to output results of my mysql query to JSON.
I have problem with serializing datetime.datetime field, so I wrote small function to do that:
def date_handler(obj):
if hasattr(obj, 'isoformat'):
return obj.isoformat()
else:
return obj
and then in main code I'm just running:
products_json = []
for code in best_matching_codes:
cur = db.cursor()
query = "SELECT * FROM %s WHERE code LIKE '%s'" % (PRODUCTS_TABLE_NAME, product_code)
cur.execute(query)
columns = [desc[0] for desc in cur.description]
rows = cur.fetchall()
for row in rows:
products_json.append(dict((k,v) for k,v in zip(columns,row)))
return json.dumps(products_json, default = date_handler)
However, since I wrote date_handler function, I'm getting "ValueError: Circular reference detected"
127.0.0.1 - - [10/Jan/2013 00:42:18] "GET /1/product?code=9571%2F702 HTTP/1.1" 500 -
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/flask/app.py", line 1701, in __call__
return self.wsgi_app(environ, start_response)
File "/Library/Python/2.7/site-packages/flask/app.py", line 1689, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/Library/Python/2.7/site-packages/flask/app.py", line 1687, in wsgi_app
response = self.full_dispatch_request()
File "/Library/Python/2.7/site-packages/flask/app.py", line 1360, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Library/Python/2.7/site-packages/flask/app.py", line 1358, in full_dispatch_request
rv = self.dispatch_request()
File "/Library/Python/2.7/site-packages/flask/app.py", line 1344, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/pisarzp/Desktop/SusyChoosy/susyAPI/test1.py", line 69, in product_search
return json.dumps(products_json, default = date_handler)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 238, in dumps
**kw).encode(obj)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 201, in encode
chunks = self.iterencode(o, _one_shot=True)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 264, in iterencode
return _iterencode(o, 0)
ValueError: Circular reference detected
What did I break? Is there a better way to serialize output to JSON?
question from:
https://stackoverflow.com/questions/14249115/serializing-output-to-json-valueerror-circular-reference-detected 与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…