Tutorial by Examples: io

Many-to-One Relationship from django.db import models class Author(models.Model): name = models.CharField(max_length=50) #Book has a foreignkey (many to one) relationship with author class Book(models.Model): author = models.ForeignKey(Author, on_delete=models.CASCADE) publish_...

While the math.sqrt function is provided for the specific case of square roots, it's often convenient to use the exponentiation operator (**) with fractional exponents to perform nth-root operations, like cube roots. The inverse of an exponentiation is exponentiation by the exponent's reciprocal. S...

The background-position property is used to specify the starting position for a background image or gradient .myClass { background-image: url('path/to/image.jpg'); background-position: 50% 50%; } The position is set using an X and Y co-ordinate and be set using any of the units used withi...

Detailed instructions on getting couchbase set up or installed.

You can use Optional Chaining in order to call a method, access a property or subscript an optional. This is done by placing a ? between the given optional variable and the given member (method, property or subscript). struct Foo { func doSomething() { print("Hello World!") ...

Install gunicorn pip install gunicorn From django project folder (same folder where manage.py resides), run the following command to run current django project with gunicorn gunicorn [projectname].wsgi:application -b 127.0.0.1:[port number] You can use the --env option to set the pat...

OptionSetType is a protocol designed to represent bit mask types where individual bits represent members of the set. A set of logical and/or functions enforce the proper syntax: struct Features : OptionSet { let rawValue : Int static let none = Features(rawValue: 0) static let feature0 = F...

You can create an ordered dictionary which will follow a determined order when iterating over the keys in the dictionary. Use OrderedDict from the collections module. This will always return the dictionary elements in the original insertion order when iterated over. from collections import Ordere...

Get the current date. LocalDate.now() Get yesterday's date. LocalDate y = LocalDate.now().minusDays(1); Get tomorrow's date LocalDate t = LocalDate.now().plusDays(1); Get a specific date. LocalDate t = LocalDate.of(1974, 6, 2, 8, 30, 0, 0); In addition to the plus and minus methods, ...

Writing testable code is an important part of building a robust, maintainable, and agile project. Support for PHP's most widely used testing framework, PHPUnit, is built right into Laravel. PHPUnit is configured using the phpunit.xml file, which resides in the root directory of every new Laravel app...

function add(a, b) return a + b end -- creates a function called add, which returns the sum of it's two arguments Let's look at the syntax. First, we see a function keyword. Well, that's pretty descriptive. Next we see the add identifier; the name. We then see the arguments (a, b) these c...

Functions are only useful if we can call them. To call a function the following syntax is used: print("Hello, World!") We're calling the print function. Using the argument "Hello, World". As is obvious, this will print Hello, World to the output stream. The returned value is ...

Creating anonymous functions Anonymous functions are just like regular Lua functions, except they do not have a name. doThrice(function() print("Hello!") end) As you can see, the function is not assigned to any name like print or add. To create an anonymous function, all you hav...

Views, in an MVC pattern, contain the logic on how to present data to the user. In a web application, typically they are used to generate the HTML output that is sent back to users with each response. By default, views in Laravel are stored in the resources/views directory. A view can be called u...

function output = mymult(a, b) % MYMULT Multiply two numbers. % output = MYMULT(a, b) multiplies a and b. % % See also fft, foo, sin. % % For more information, see <a href="matlab:web('https://google.com')">Google</a>. output = a * b; end help mymult then p...

After following the instructions above and installing Leiningen, start a new project by running: lein new <project-name> This will setup a Clojure project with the default Leiningen template within the <project-name> folder. There are several templates for Leiningen, which affect the...

Functions in Common Lisp are first class values. An anonymous function can be created by using lambda. For example, here is a function of 3 arguments which we then call using funcall CL-USER> (lambda (a b c) (+ a (* b c))) #<FUNCTION (LAMBDA (A B C)) {10034F484B}> CL-USER> (defvar *fo...

Any symbol in Common Lisp has a slot for a variable to be bound and a separate slot for a function to be bound. Note that the naming in this example is only for illustration. Global variables should not be named foo, but *foo*. The latter notation is a convention to make it clear that the variable ...

Common Lisp contains many higher order functions which are passed functions for arguments and call them. Perhaps the most fundamental are funcall and apply: CL-USER> (list 1 2 3) (1 2 3) CL-USER> (funcall #'list 1 2 3) (1 2 3) CL-USER> (funcall #'list 1 2 3 4 5) (1 2 3 4 5) CL-USER&g...

A very useful feature of Swift 2.2 is having the ability of extending protocols. It works pretty much like abstract classes when regarding a functionality you want to be available in all the classes that implements some protocol (without having to inherit from a base common class). protocol FooPro...