Importing data to a particular model - json

Question

I'm starting with instances of Order object and trying to transform them into a JSON format, which will be used to update a table. I'm new to Django-specific code constructs.
My chosen approach is:
Load the data from database as multiple Order instances
Transform the Order instances into an intermediary Table object (the format is given)
Serialize the Table object into JSON
I have gone quite far so far, but I can't make the whole application run, except for running it in the Python shell. I have the models and serializers already in place.
Can someone offer his help how to mark all Order instances at once and transform them to Table in one API call and anything else that is missing in this simple example?
models.py:
# Order corresponds to Line in the Table
class Order(models.Model):
doc = models.CharField(max_length=200, blank=True, null=True)
order = models.CharField(max_length=200, blank=True, null=True)
nothing = models.CharField(max_length=200, blank=True, null=True)
def __str__(self):
return self.order
class Table(models.Model):
pass
class Column(models.Model):
data = models.CharField(max_length=200, blank=True, null=True)
table = models.ForeignKey(Table)
def __str__(self):
return self.data
class Line(models.Model):
doc = models.CharField(max_length=200, blank=True, null=True)
order = models.CharField(max_length=200, blank=True, null=True)
nothing = models.CharField(max_length=200, blank=True, null=True)
table = models.ForeignKey(Table)
def __str__(self):
return self.order
serializers.py:
class TableSerializer(serializers.ModelSerializer):
columns = ColumnSerializer(many=True)
lines = LineSerializer(many=True)
class Meta:
model = Table
fields = [
'columns',
'lines'
]
class ColumnSerializer(serializers.ModelSerializer):
class Meta:
model = Column
fields = [
'data'
]
class LineSerializer(serializers.ModelSerializer):
class Meta:
model = Line
fields = [
'doc',
'order',
'nothing'
]
For this relational data:
doc order nothing
564251422 564210 5648
546546545 98745 4668
JSON output should be:
{
"columns": [
{
"data": "doc"
},
{
"data": "order"
},
{
"data": "nothing"
}
],
"lines": [
{
"doc": "564251422",
"nothing": 0.0,
"order": "56421"
},
{
"doc": "546546545",
"nothing": 0.0,
"order": "98745"
}
]
}
Shell commands:
import polls.models
polls.models.Order.objects.all() # outputs all orders
table = polls.models.Table()
polls.models.Column(data="doc",table=table)
polls.models.Column(data="order",table=table)
polls.models.Column(data="nothing",table=table)
polls.models.Line(doc="564251422",order="56421",nothing="0.0",table=table)
polls.models.Line(doc="546546545",order="98745",nothing="0.0",table=table)
views.py (update):
bunch = OrderSerializer(Order.objects.all(), many=True)
headers = bunch.data[0].keys()
headers_prepared = map (lambda x: {'data': x} , headers)
ordered_all = ( ('columns', headers_prepared), ('lines', bunch.data) )
data = collections.OrderedDict(ordered_all)
data_json = JSONRenderer().render(data)
return JsonResponse(data_json, safe=False)

Answer 1

As I see this question may relate to another (mentioned in comments) , but for this particular case...
As you are using DjangoRestFramework (the right way), to get all data in Json format you may:
in serialisers.py:
from rest_framework import serializers
from polls.models import Order
class OrderSerializer(serializers.ModelSerializer):
class Meta:
model = Order
fields = ('doc', 'order', 'nothing')
# note we do not use other serializers
next in shell (views in future):
from rest_framework.renderers import JSONRenderer
from polls.models import Order
from polls.serializers import OrderSerializer
bunch = OrderSerializer(Order.objects.all(), many=True)
#this will output "lines" part of desired output
JSONRenderer().render(bunch.data)
#next to get columns, or i say headers
headers = bunch.data[0].keys()
# headers = ['doc','order','nothing']
# !note will fail if bunch.data is empty
headers_prepared = map (lambda x: {'data': x} , headers)
# headers_prepared = [{'data': 'doc'}, {'data': 'order'}, {'data': 'nothing'}]
import collections # need to use OrderedDict to store in our sequence
ordered_all = ( ('columns', headers_prepared), ('lines', bunch.data) )
#finally desired output
JSONRenderer().render( collections.OrderedDict(ordered_all) )
#all code and output tested on my dummy data
UPDATE in urls.py:
urlpatterns = [
...
url(r'my/', my),
...
]
add in views.py:
#as you sileny JSONResponse (from RestFramework docs) - need to show it
from django.http import HttpResponse
class JSONResponse(HttpResponse):
"""
An HttpResponse that renders its content into JSON.
"""
def __init__(self, data, **kwargs):
content = JSONRenderer().render(data)
kwargs['content_type'] = 'application/json'
super(JSONResponse, self).__init__(content, **kwargs)
#now our view
import collections
def my(request):
bunch = OrderSerializer(Order.objects.all(), many=True)
# to get headers independent of presence of orders
empty = OrderSerializer()
headers = empty.data.keys()
headers_prepared = map (lambda x: {'data': x} , headers)
ordered_all = ( ('columns', headers_prepared), ('lines', bunch.data) )
out = collections.OrderedDict(ordered_all)
#finally desired output
return JSONResponse( out )