Parse nested JSON in Flask - json

Question

I have a REST API endpoint in which I need to parse incoming nested JSON of the format:
site: {
id: '37251',
site_name: 'TestSite',
address: {
'address': '1234 Blaisdell Ave',
'city': 'Minneapolis',
'state': 'MN',
'zip': '55456',
'neighborhood': 'Kingfield',
'county': 'Hennepin',
},
geolocation: {
latitude : '41.6544',
longitude : '73.3322',
accuracy: '45'
}
}
into the following SQLAlchemy classes:
Site:
class Site(db.Model):
__tablename__ = 'site'
id = Column(Integer, primary_key=True, autoincrement=True)
site_name = Column(String(80))# does site have a formal name
address_id = Column(Integer, ForeignKey('address.id'))
address = relationship("Address", backref=backref("site", uselist=False))
geoposition_id = Column(Integer, ForeignKey('geoposition.id'))
geoposition = relationship("Geoposition", backref=backref("site", uselist=False))
evaluations = relationship("Evaluation", backref="site")
site_maintainers = relationship("SiteMaintainer", backref="site")
Address (a Site has one Address):
class Address(db.Model):
__tablename__ = 'address'
id = Column(Integer, primary_key=True, autoincrement=True)
address = Column(String(80))
city = Column(String(80))
state = Column(String(2))
zip = Column(String(5))
neighborhood = Column(String(80))
county = Column(String(80))
and Geoposition (a Site has one Geoposition):
class Geoposition(db.Model):
__tablename__ = 'geoposition'
id = Column(Integer, primary_key=True, autoincrement=True)
site_id = Column(Integer)
latitude = Column(Float(20))
longitude = Column(Float(20))
accuracy = Column(Float(20))
timestamp = Column(DateTime)
Getting the SQLAlchemey data into JSON is easy, but I need to parse the JSON from my request so that I can append/update data that is sent via POST to the RESTful API. I know how to handle non-nested JSON, but I will be the first to admit that I am clueless in dealing with the nested JSON for records that belong to multiple tables in a relational structure.
I've tried searching high and low for this without any luck. Closest I could find is here "Nested validation with the flask-restful RequestParser", but this is not clicking for what I need to do based on my nested structure.

Answer 1

Cool! Looks like Flask handles this through the request handler:
With this JSON:
site: {
"id": "37251",
"site_name": "TestSite",
"address": {
"address": "1234 Blaisdell Ave",
"city": "Minneapolis",
"state": "MN",
"zip": "55456",
"neighborhood": "Kingfield",
"county": "Hennepin"
},
geolocation: {
latitude : "41.6544",
longitude : "73.3322",
accuracy: "45"
}
}
Sent to this endpoint:
#app.route('/api/resource', methods=['GET','POST','OPTIONS'])
#cross_origin() # allow all origins all methods
#auth.login_required
def get_resource():
# Get the parsed contents of the form data
json = request.json
print(json)
# Render template
return jsonify(json)
I get the following object:
{u'site': {u'geolocation': {u'latitude': u'41.6544', u'longitude': u'73.3322', u'accuracy': u'45'}, u'site_name': u'TestSite', u'id': u'37251', u'address': {u'city': u'Minneapolis', u'neighborhood': u'Kingfield', u'zip': u'55456', u'county': u'Hennepin', u'state': u'MN', u'address': u'1234 Blaisdell Ave'}}}
UPDATE:
Am able to access all my dictionary items just fine using this code for a test in my endpoint:
# print entire object
print json['site']
# define dictionary item for entire object
site = json['site']
print site["site_name"]
# print address object
print site['address']
# define address dictionary object
address = json['site']['address']
print address["address"]
# define geolocation dictionary object
geolocation = json['site']['geolocation']
print geolocation["accuracy"]
In retrospect, this seems rather trivial now. I hope this helps someone in the future.

Answer 2

Do you have access and can edit the JSON?
A few edits would help make it a valid JSON:
Use double quotes for keys and values
Open and close JSON with { and }
Delete the trailing , in the country line
If you can do so, you JSON will look like this:
{
"site": {
"id": "37251",
"site_name": "TestSite",
"address": {
"address": "1234BlaisdellAve",
"city": "Minneapolis",
"state": "MN",
"zip": "55456",
"neighborhood": "Kingfield",
"county": "Hennepin"
},
"geolocation": {
"latitude": "41.6544",
"longitude": "73.3322",
"accuracy": "45"
}
}
}
Sorting that out, use Python's json to deal with it:
import json
file_handler = open('test.json', 'r')
parsed_data = json.loads(file_handler.read())
print parsed_data
The output is a diciotnary that you can easily iterate with to validate your data:
{u'site': {u'geolocation': {u'latitude': u'41.6544', u'longitude': u'73.3322', u'accuracy': u'45'}, u'site_name': u'TestSite', u'id': u'37251', u'address': {u'city': u'Minneapolis', u'neighborhood': u'Kingfield', u'zip': u'55456', u'county': u'Hennepin', u'state': u'MN', u'address': u'1234BlaisdellAve'}}}
But if you can't edit your JSON to make its syntax better, json.loads would not parse it…