Tutorial by Examples: d

In DRF, serializer validation is run in a specific, undocumented order Field deserialization called (serializer.to_internal_value and field.run_validators) serializer.validate_[field] is called for each field. Serializer-level validators are called (serializer.run_validation followed by seriali...

It is possible to DELETE data from a table if it matches (or mismatches) certain data in other tables. Let's assume we want to DELETEdata from Source once its loaded into Target. DELETE FROM Source WHERE EXISTS ( SELECT 1 -- specific value in SELECT doesn't matter FROM Target ...

This example shows how to create a pyramid using borders and 2D transformation methods skewY() and rotate() on pseudo elements. HTML: <div class="pyramid"></div> CSS: .pyramid { width: 100px; height: 200px; position: relative; margin: 50px; } .pyramid::b...

The NSInteger is just a typedef for either an int or a long depending on the architecture. The same goes for a NSUInteger which is a typedef for the unsigned variants. If you check the NSInteger you will see the following: #if __LP64__ || (TARGET_OS_EMBEDDED && !TARGET_OS_IPHONE) || TARGET_...

from multiprocessing import Pool def cube(x): return x ** 3 if __name__ == "__main__": pool = Pool(5) result = pool.map(cube, [0, 1, 2, 3]) Pool is a class which manages multiple Workers (processes) behind the scenes and lets you, the programmer, use. Pool(5) creat...

Here is an example of custom UITextField that takes only numerical text and discards all other. NOTE: For iPhone it is easy to do this using Number type keyboard, but for iPad there is no keyboard with Numbers only class NumberTextField: UITextField { required init(coder aDecoder: NSCoder) ...

If we want to disable all the actions like Copy, Paste, Replace, Select, etc from UITextField then we can use following custom text field: class CustomTextField: UITextField { var enableLongPressActions = false required init(coder aDecoder: NSCoder) { super.init(coder: aDecoder)! } o...

%TYPE: Used to declare a field with the same type as that of a specified table's column. DECLARE vEmployeeName Employee.Name%TYPE; BEGIN SELECT Name INTO vEmployeeName FROM Employee WHERE RowNum = 1; DBMS_OUTPUT.PUT_LINE(vEmp...

Parameter TypesReturn TypeInterface()voidRunnable()TSupplier()booleanBooleanSupplier()intIntSupplier()longLongSupplier()doubleDoubleSupplier(T)voidConsumer<T>(T)TUnaryOperator<T>(T)RFunction<T,R>(T)booleanPredicate<T>(T)intToIntFunction<T>(T)longToLongFunction<T>(...

You can define a function to be recursive with the rec keyword, so it can call itself. # let rec fact n = match n with | 0 -> 1 | n -> n * fact (n - 1);; val fact : int -> int = <fun> # fact 0;; - : int = 1 # fact 4;; - : int = 24 You can also define mutually re...

General Imports, using jinja2 to populate templates into htmls. import jinja2 import webapp2 Important import to use Users API: from google.appengine.api import users Setting of Jinja environment: [into the example the tehcnology selected to populate the information into the frontend] JINJ...

Simple extract of index.html: <div class="sign-in"> {% if user %} [Passing the url we have the opportunity to logout the user] <a href="{{ url|safe }}">LOG OUT</a> [You can include here operations for user authenticated] ...

Once you're up with a new project with the basic template provided in the Introduction, you should be able to add a LUISRecognizer like so - var model = '' // Your LUIS Endpoint link comes here var recognizer = new builder.LuisRecognizer(model); Now, recognizer is a LUISRecognizer and can pa...

If we want our app data to be protected against iTunes backups, we have to skip our app data from being backed up in iTunes. Whenever iOS device backed up using iTunes on macOS, all the data stored by all the apps is copied in that backup and stored on backing computer. But we can exclude our app ...

Suppose we have a POJO class User we need to validate. public class User { @NotEmpty @Size(min=5) @Email private String email; } and a controller method to validate the user instance public String registerUser(@Valid User user, BindingResult result); Let's extend the U...

Component: <md2-select [(ngModel)]="item" (change)="change($event)" [disabled]="disabled"> <md2-option *ngFor="let i of items" [value]="i.value" [disabled]="i.disabled"> {{i.name}}</md2-option> </md2-select> ...

Tooltip is a directive, it allows the user to show hint text while the user mouse hover over an element. A tooltip would have the following markup. <span tooltip-direction="left" tooltip="On the Left!">Left</span> <button tooltip="some message" ...

Toast is a service, which show notifications in the view. Creates and show a simple toast noticiation. import {Md2Toast} from 'md2/toast/toast'; @Component({ selector: "..." }) export class ... { ... constructor(private toast: Md2Toast) { } toastMe() { this.toast.show(...

Assume that, we implement a simple API and we have the following models. class Parent(models.Model): name = models.CharField(max_length=50) class Child(models.Model): parent = models.ForeignKey(Parent) child_name = models.CharField(max_length=80) And we want to return a respo...

This command allows you to change or view the TLD (top-level domain) used to bind domains to your local machine. Get The Current TLD $ valet domain > dev Set the TLD $ valet domain local > Your Valet domain has been updated to [local].