Tutorial by Examples: t

Let's say you have a simple myblog app with the following model: from django.conf import settings from django.utils import timezone class Article(models.Model): title = models.CharField(max_length=70) slug = models.SlugField(max_length=70, unique=True) author = models.ForeignKe...

Sometimes, your template need a bit more of information. For example, we would like to have the user in the header of the page, with a link to their profile next to the logout link. In these cases, use the get_context_data method. views.py class BookView(DetailView): template_name = "boo...

Template views are fine for static page and you could use them for everything with get_context_data but it would be barely better than using function as views. Enter ListView and DetailView app/models.py from django.db import models class Pokemon(models.Model): name = models.CharField(max...

Writing a view to create object can be quite boring. You have to display a form, you have to validate it, you have to save the item or return the form with an error. Unless you use one of the generic editing views. app/views.py from django.core.urlresolvers import reverse_lazy from django.views.g...

The basic idea of a class template is that the template parameter gets substituted by a type at compile time. The result is that the same class can be reused for multiple types. The user specifies which type will be used when a variable of the class is declared. Three examples of this are shown in m...

In order to create a random user password we can use the symbols provided in the string module. Specifically punctuation for punctuation symbols, ascii_letters for letters and digits for digits: from string import punctuation, ascii_letters, digits We can then combine all these symbols in a name...

In Go, an interface is just a set of methods. We use an interface to specify a behavior of a given object. type Painter interface { Paint() } The implementing type need not declare that it is implementing the interface. It is enough to define methods of the same signature. type Rembrandt ...

To start a new thread: use std::thread; fn main() { thread::spawn(move || { // The main thread will not wait for this thread to finish. That // might mean that the next println isn't even executed before the // program exits. println!("Hello from spa...

The jQuery UI framework helps to extend and increase the User Interface controls for jQuery JavaScript library. When you wish to use jQuery UI, you will need to add these libraries to your HTML. A quick way to start is using the Content Delivery Network available code sources: jQuery Libraries ht...

You can create a tuple and use a switch like so: var str: String? = "hi" var x: Int? = 5 switch (str, x) { case (.Some,.Some): print("Both have values") case (.Some, nil): print("String has a value") case (nil, .Some): print("Int has a value&...

Assuming you have a model called Post defined in your models.py file that contains blog posts, and has a date_published field. Step 1: Write the context processor Create (or add to) a file in your app directory called context_processors.py: from myapp.models import Post def recent_blog_posts...

<script> $( ".inclas").datepicker({ minDate: new Date(2007, 1 - 1, 1) maxDate: new Date(2008, 1 - 1, 1) }); </script> <input type ="text" id="datepick" class="inclas">

The simple answer is that it allows you to evolve an existing interface without breaking existing implementations. For example, you have Swim interface that you published 20 years ago. public interface Swim { void backStroke(); } We did a great job, our interface is very popular, there ar...

Following the Rcpp example in this documentation entry, consider the following tough-to-vectorize function, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <-...

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_...

This example of the Sortable using a Placeholder is common usage. Sortable is applied to a group of DOM elements, allowing the user to move items around in the list via Drag'n Drop style actions. <!doctype html> <html lang="en"> <head> <meta charset="utf-8&q...

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...

To access entities declared in a module from another program unit (module, procedure or program), the module must be used with the use statement. module shared_data implicit none integer :: iarray(4) = [1, 2, 3, 4] real :: rarray(4) = [1., 2., 3., 4.] end module program test !...

At some point in your use of Django, you may find yourself wanting to interact with tables which have already been created, or with database views. In these cases, you would not want Django to manage the tables through its migrations. To set this up, you need to add only one variable to your model's...

Literal format strings were introduced in PEP 498 (Python3.6 and upwards), allowing you to prepend f to the beginning of a string literal to effectively apply .format to it with all variables in the current scope. >>> foo = 'bar' >>> f'Foo is {foo}' 'Foo is bar' This works wi...