This post is deprecated as its based on Django 1.6 mostly.
I am going to share some useful Django tools/functions which are very useful(were for me atleast) to get things done.
Return any model class and its properties ︎
This method will return any model class if you have the name of the class.
from django.db import models def get_model_description(model_name=None, return_property_list=True): for item in models.get_models(include_auto_created=True): if item.__name__ == model_name: if return_property_list is True: return item.get_trigger_properties() else: return item return 
For usage, let us think of an example. Let us think, we have a class name ‘X’, we will get the class instance using it like this:
from usefultools import get_model_descriptor model_x = get_model_descriptor(model_name='X') #will get class model_x_objects = get_model_descriptor(model_name='X').objects.all() #will get all the objects of this class
And for its property:
from usefultools import get_model_descriptor model_x = get_model_descriptor(model_name='X', return_property_list=True) #will get a list of properties like ['a_property','b_property']
Distance calculator ︎
If you input latitude and longitude of two places, this function will return the distance in between them. Got help from here: http://code.activestate.com/recipes/576779-calculating-distance-between-two-geographic-points/
import math def distance_calculator(lat1, long1, lat2, long2): lat1, long1, lat2, long2 = float(lat1), float(long1), float(lat2), float(long2) degrees_to_radians = math.pi/180.0 phi1 = (90.0 - lat1)*degrees_to_radians phi2 = (90.0 - lat2)*degrees_to_radians theta1 = long1*degrees_to_radians theta2 = long2*degrees_to_radians cos = (math.sin(phi1)*math.sin(phi2)*math.cos(theta1 - theta2) + math.cos(phi1)*math.cos(phi2)) arc = math.acos( cos ) distance = arc*6378.1 return distance
It will return the distance in KM.
Dynamic relational operations ︎
Suppose we have a sentence like:
'5 is greater than 9' and check if its true. We could use
eval to dynamically converty string to python but its highly not recommended. So I tried like this:
def calculate_relational_operation(lhs, rhs, operator): get_type = type(lhs).__name__ if get_type == 'str': rhs = str(rhs) elif get_type == 'float': rhs = float(rhs) elif get_type == 'int': rhs = int(rhs) if operator == "==": if lhs == rhs: return True return False elif operator == "!=": if lhs != rhs: return True return False elif operator == ">": if lhs > rhs: return True return False elif operator == "<": if lhs < rhs: return True return False elif operator == ">=": if lhs >= rhs: return True return False elif operator == "<=": if lhs == rhs: return True return False elif operator == "Is": if lhs is rhs: return True return False return False
It will return True or False depending on the statement/input.
Get week list ︎
It will return all the weeks list from last 1 year (extendable).
from isoweek import Week def generate_week(): max_week = datetime.datetime.combine(Week.thisweek().thursday(), datetime.time(0,0)) min_week = max_week - datetime.timedelta(days=365) _weeks = list() while True: _weeks.append('Week'+str(max_week.isocalendar())+ ' ' +str(max_week.isocalendar()))) max_week -= datetime.timedelta(days=7) if max_week <= min_week: break return _weeks #Output>> ['Week2 2015', 'Week1 2015', 'Week52 2014' ....]
Get month list ︎
It will return last 12 month’s year and month number. Constructed using this Stack Overflow answer.
x = 12 now = time.localtime() print([time.localtime(time.mktime((now.tm_year, now.tm_mon - n, 1, 0, 0, 0, 0, 0, 0)))[:2] for n in range(x)]) #Output>> [(2015, 2), (2015, 1), (2014, 12), (2014, 11), (2014, 10), (2014, 9), (2014, 8), (2014, 7), (2014, 6), (2014, 5), (2014, 4), (2014, 3)]
Thats it. Thanks for reading.
Last updated: Nov 13, 2020