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Initiating a GET request to Django web api and send a list of ids as an array

I'm trying to call a rest API in django and send a list of Ids as a paremeter (I can't use query string).
This works if I send only one, but how to specify it for an array of integers:
path('details/<int:id>/', views.get_details),
def get_details(request, id=0)
What if I have a method that will take a list of Ids:
def get_data(request, ids=[])
How should the url be defined so that the ids array is populated?

You can parse ids list manually like this
path('details/<ids>/', views.get_details),
def parse_ids(ids: str):
result = []
for id in ids.split(','):
try:
result.append(int(id))
except ValueError:
pass
return result
def get_details(request, ids):
id_list = parse_ids(ids)
# do stuff
...

Python: Handle Missing Object keys in mapping and continue instructions

I'm fairly new to Python so bear with me please.
I have a function that takes two parameters, an api response and an output object, i need to assign some values from the api response to the output object:
def map_data(output, response):
try:
output['car']['name'] = response['name']
output['car']['color'] = response['color']
output['car']['date'] = response['date']
#other mapping
.
.
.
.
#other mapping
except KeyError as e:
logging.error("Key Missing in api Response: %s", str(e))
pass
return output
Now sometimes, the api response is missing some keys i'm using to generate my output object, so i used the KeyError exception to handle this case.
Now my question is, in a case where the 'color' key is missing from the api response, how can i catch the exception and continue to the line after it output['car']['date'] = response['date'] and the rest of the instructions.
i tried the pass instruction but it didn't have any affect.
Ps: i know i can check the existence of the key using:
if response.get('color') is not None:
output['car']['color'] = response['color']
and then assign the values but seeing that i have about 30 values i need to map, is there any other way i can implement ? Thank you

A few immediate ideas
(FYI - I'm not going to explain everything in detail - you can check out the python docs for more info, examples etc - that will help you learn more, rather than trying to explain everything here)
Google 'python handling dict missing keys' for a million methods/ideas/approaches - it's a common use case!
Convert your response dict to a defaultdict. In that case you can have a default value returned (eg None, '', 'N/A' ...whatever you like) if there is no actual value returned.
In this case you could do away with the try and every line would be executed.
from collections import defaultdict
resp=defaultdict(lambda: 'NA', response)
output['car']['date'] = response['date'] # will have value 'NA' if 'date' isnt in response
Use the in syntax, perhaps in combination with a ternary else
output['car']['color'] = response['color'] if 'color' in response
output['car']['date'] = response['date'] if 'date' in response else 'NA'
Again you can do away with the try block and every line will execute.
Use the dictionary get function, which allows you to specify a default if there is no value for that key:
output['car']['color'] = response.get('car', 'no car specified')

You can create a utility function that gets the value from the response and if the value is not found, it returns an empty string. See example below:
def get_value_from_response_or_null(response, key):
try:
value = response[key]
return value
except KeyError as e:
logging.error("Key Missing in api Response: %s", str(e))
return ""
def map_data(output, response):
output['car']['name'] = get_value_from_response_or_null(response, 'name')
output['car']['color'] = get_value_from_response_or_null(response, 'color')
output['car']['date'] = get_value_from_response_or_null(response, 'date')
# other mapping
# other mapping
return output

Django CursorPagination for ordering by several fields

I am using Django DRF's CursorPagination for lazy loading of my data, and currently my goal is to sort the data by more than one field.
This is how my code looks like now:
class EndlessPagination(CursorPagination):
ordering_param = ''
def set_ordering_param(self, request):
self.ordering = request.query_params.get(self.ordering_param, None)
if not self.ordering:
raise ValueError('Url must contain a parameter named ' +
self.ordering_param)
if self.ordering.startswith("\"") or self.ordering.endswith("\""):
raise ValueError('Ordering parameter should not include quotation marks'
def paginate_queryset(self, queryset, request, view=None):
# This function is designed to set sorting param right in the URL
self.set_ordering_param(request)
return super(EndlessPagination, self).paginate_queryset(queryset, request, view)
This code works fine for urls like my_url/sms/270380?order_by=-timestamp, but what if I want to sort by several fields ?

Use str.split() to split the url params
class EndlessPagination(CursorPagination):
ordering_param = 'order_by'
def set_ordering_param(self, request):
ordering_param_list = request.query_params.get(self.ordering_param, None)
self.ordering = ordering_param_list.split(',')
# here, "self.ordering" will be a "list", so, you should update the validation logic
"""
if not self.ordering:
raise ValueError('Url must contain a parameter named ' +
self.ordering_param)
if self.ordering.startswith("\"") or self.ordering.endswith("\""):
raise ValueError('Ordering parameter should not include quotation marks'
"""
def paginate_queryset(self, queryset, request, view=None):
# This function is designed to set sorting param right in the URL
self.set_ordering_param(request)
return super(EndlessPagination, self).paginate_queryset(queryset, request, view)
Example URLs
1. my_url/sms/270380?order_by=-timestamp
2. my_url/sms/270380?order_by=-timestamp,name
3. my_url/sms/270380?order_by=-name,foo,-bar
UPDATE-1
First of all thanks to you for giving a chance to dig deep :)
As you said, me too didn't see comma seperated query_params in popular APIs. So, Change the url format to something like,my_url/sms/270380??order_by=-name&order_by=foo&order_by=-bar
At this time, the request.query_params['order_by'] will be a list equal to ['-name','foo','-bar']. So, you don't want to use the split() function, hence your set_ordering_param() method become,
def set_ordering_param(self, request):
self.ordering = request.query_params.get(self.ordering_param, None)
#...... your other validations

Django - checking if instance exists results in internal server error 500

I am trying to check if I have an entry in my database using this code:
def device_update(request):
json_data = json.loads(request.body)
email = json_data['email']
imei = json_data['imei']
sdk_version = json_data['sdk_version']
date = json_data['updateDate']
rule = json_data['ruleName']
group_name = json_data['group']
if Group.objects.filter(group=group_name).exists():
print("group does exists")
else:
print("group doesn't exists")
return HttpResponse("Successful")
However, when the code reaches the if statement to check if the group exists, it returns error 500.
I tried to check with two groups one that exists and another one that doesn't, in both cases I got error 500.
How can I fix this and why is this happening?

The logic for checking if a Group exists, i.e. the line:
if Group.objects.filter(group=group_name).exists()
is not throwing the error here. It is likely that json_data is missing one of the keys you expect it to have, for example, 'group'.
I'd recommend using the get method that dictionaries have. This provides default values when the specified key is not present in the dictionary. You should also have error handling for when the request body is not in valid JSON format.
Here's an example:
def device_update(request):
try:
json_data = json.loads(request.body)
except json.JSONDecodeError:
return HttpResponse('Request body must be in valid JSON format')
email = json_data.get('email', '')
imei = json_data.get('imei', '')
sdk_version = json_data.get('sdk_version', '')
date = json_data.get('updateDate', '')
rule = json_data.get('ruleName', '')
group_name = json_data.get('group', '')
if Group.objects.filter(group=group_name).exists():
print("group does exists")
else:
print("group doesn't exists")
return HttpResponse("Successful")
I set the defaults to the empty string '', but you may want to change that.

Your view doesn't have any error handling. Looking at it quickly, at least two things could go wrong. The request body might not be valid json, and if it is valid json, it might not contain the required keys.
def device_update(request):
try:
json_data = json.loads(request.body)
except ValueError:
return HttpResponse("Invalid json")
try:
email = json_data['email']
imei = json_data['imei']
sdk_version = json_data['sdk_version']
date = json_data['updateDate']
rule = json_data['ruleName']
group_name = json_data['group']
except KeyError as e:
return HttpResponse("Missing Key %s" % e[0])
...
Writing your own validation for a single view like this is ok. As it gets more complicated, you might want to look at django rest framework. It has serializers which will help you manage validation.

Alasdair/Keselme, looks that your view is correct.
Try to put the ipdb into your code in order to debug your code, and than you can print the request.data and see what is comming in the request.

How to obtain a single resource through its ID from a URL?

I have an URL such as: http://example.com/page/page_id
I want to know how to get the page_id part from url in the route. I am hoping I could devise some method such as:
#route('/page/page_id')
def page(page_id):
pageid = page_id

It's pretty straightforward - pass the path parameter in between angle brackets, but be sure to pass that name to your method.
#app.route('/page/<page_id>')
def page(page_id):
pageid = page_id
# You might want to return some sort of response...

You should use the following syntax:
#app.route('/page/<int:page_id>')
def page(page_id):
# Do something with page_id
pass

You can specify the ID as integer :
#app.route('/page/<int:page_id>')
def page(page_id):
# Replace with your custom code or render_template method
return f"<h1>{page_id}</h1>"
or if you are using alpha_num ID:
#app.route('/page/<username>')
def page(username):
# Replace with your custom code or render_template method
return f"<h1>Welcome back {username}!</h1>"
It's also possible to not specify any argument in the function and still access to URL parameters :
# for given URL such as domain.com/page?id=123
#app.route('/page')
def page():
page_id = request.args.get("id") # 123
# Replace with your custom code or render_template method
return f"<h1>{page_id}</h1>"
However this specific case is mostly used when you have FORM with one or multiple parameters (example: you have a query :
domain.com/page?cars_category=audi&year=2015&color=red
#app.route('/page')
def page():
category = request.args.get("cars_category") # audi
year = request.args.get("year") # 2015
color = request.args.get("color") # red
# Replace with your custom code or render_template method
pass
Good luck! :)