marctc

System Design Cheatsheet

To Remember

• Have they gathered requirements?
• Have they defined the systems interface?
• Have they done scaling/capacity estimation?
• Does the design actually work?
• reliable and maintainable?
• Is the design feasible to implement - fit within our practical constraints (budget, time, etc.)??

marctc

import django_filters


class WildcardFilter(django_filters.Filter):

    @staticmethod
    def process_wildcard_value(value):
        """
        Given a filter value in wildcard mode it returns the clean value and the need lookup
        Ex:

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class ContentTypeField(serializers.Field):

    def to_representation(self, value):
        return value.model

    def to_internal_value(self, data):
        try:
            return ContentType.objects.get(app_label='core', model=data)
        except ContentType.DoesNotExist:
            raise ValidationError("'{}' model does not exist".format(data))

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    def test_are_remaining_box_codes(self, box, box_codes):
        """
        There are remaining box codes on the installation and so availability
        """
        with patch('django.db.models.fields.related_descriptors.ForwardManyToOneDescriptor.__get__'):
            qs = QuerySetMock(BoxCode, *box_codes)
            box.box_codes.return_value = qs
            assert box.paddle.are_remaining_box_codes()

marctc

class NamedModelChoiceFilter(django_filters.ModelMultipleChoiceFilter):

    def __init__(self, *args, **kwargs):
        super(NamedModelChoiceFilter, self).__init__(*args, **kwargs)
        self.field.widget.attrs['data-placeholder'] = self.label

marctc

class DetailPagination(PageNumberPagination):
    page_size_query_param = 'page_size'

    def get_paginated_response(self, data):
        return Response({
            'next': self.get_next_link(),
            'previous': self.get_previous_link(),
            'count': self.page.paginator.count,
            'current_page': self.page.number,
            'num_pages': self.page.paginator.num_pages,

marctc

# views

class BaseAPIView(APIView):
    serializer_valid_function_name = 'process'

    def get_serializer(self, data, request):
        return self.serializer_class(data=data, context={'request': request})

    def perform_request(self, request, **kwargs):
        data = request.data.copy()

marctc

# -*- coding: utf-8 -*-

import bleach

from django.db import models


class ModelSanitizerMixin(object):
    allowed_tags = ['p', 'em', 'strong', 'h1', 'br', 'ul', 'ol', 'li', 'a']

marctc

# -*- coding: utf-8 -*-
import os

from django.core.files.storage import FileSystemStorage
from django.utils.text import slugify


class SlugFileSystemStorage(FileSystemStorage):

    def get_valid_name(self, name):

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class BasePrimaryKeyField(IntegerField):
    model = None

    def to_representation(self, value):
        return value.id

    def to_internal_value(self, data):
        try:
            return self.model.objects.get(pk=data)
        except self.model.DoesNotExist: