Software engineering facts, information, and skills categorized as Python

Django Q objects

Priya Philip 3 weeks, 5 days ago

Q objects (django.db.models.Q) is an object used to encapsulate a collection of keyword arguments.

Generators in Python

Priya Philip 1 month ago

Generators are used to create iterators, but with a different approach. Generators are simple functions which return an iterable set of items, one at a time, in a special way.

Defining and sending django signals

Priya Philip 1 month ago

Defining signals

class Signal(providing_args=list)

All signals are  django.dispatch.Signal instances. The providing_args is a list of the names of arguments the signal will provide to listeners.

HttpRequest methods

Priya Philip 1 month, 2 weeks ago
HttpRequest represents an incoming HTTP request, including all HTTP headers and user-submitted data

HttpRequest attributes

Priya Philip 1 month, 2 weeks ago

Django uses request and response objects to pass state through the system. When a page is requested, Django creates an HttpRequest object that contains metadata about the request. Then Django loads the appropriate view, passing the HttpRequest as the first argument to the view function. Each view is responsible for returning an HttpResponse object.

Infinite iterators in Python

Priya Philip 1 month, 3 weeks ago

An object representing a stream of data. Repeated calls to the iterator’s __next__() method (or passing it to the built-in functionnext()) return successive items in the stream. When no more data are available a StopIteration exception is raised instead. At this point, the iterator object is exhausted and any further calls to its __next__() method just raise StopIteration again. Iterators are required to have an __iter__() method that returns the iterator object itself so every iterator is also iterable and may be used in most places where other iterables are accepted. One notable exception is code which attempts multiple iteration passes. A container object (such as a list) produces a fresh new iterator each time you pass it to the iter() function or use it in a for loop. Attempting this with an iterator will just return the same exhausted iterator object used in the previous iteration pass, making it appear like an empty container.

__str__ vs __repr__ in Python

Priya Philip 2 months ago

Both __repr__ and __str__ are used to represent objects in different ways.The default implementation of __repr__ for a str value can be called as an argument to eval, and the return value would be a valid string object.

Difference between null=True, blank=True in django

Priya Philip 1 year, 5 months ago

The main differnce for null and blank is 

How to deal with “SubfieldBase has been deprecated. Use Field.from_db_value...

Varghese Chacko 1 year, 5 months ago

How to deal with "SubfieldBase has been deprecated. Use Field.from_db_value instead." On upgrade to Django 1.9, we may now get the warning

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