Tutorial by Examples: el

If we have a Model as following, from django.db import models from django.contrib.auth.models import User class UserModuleProfile(models.Model): user = models.OneToOneField(User) expired = models.DateTimeField() admin = models.BooleanField(default=False) employee_id = models...

The & operator is the parent selector. When used in or as a selector, it is replaced with the full parent selectors (entire sequence of selectors right upto to the topmost level of a nested block) in the final CSS output. It is useful when creating nested rules that require using the parent sel...

Less allows the usage of the parent selector (&) anywhere in a complex selector and thus allows changing styles when the current element is within another element which gives it a different context: For example, in the below code the parent selector is placed at the end and thus it actually be...

public static async Task<WriteableBitmap> RenderUIElement(UIElement element) { var bitmap = new RenderTargetBitmap(); await bitmap.RenderAsync(element); var pixelBuffer = await bitmap.GetPixelsAsync(); var pixels = pixelBuffer.ToArray(); var writeableBitmap = new W...

A while loop is used to execute a piece of code while a condition is true. The while loop is to be used when a block of code is to be executed a variable number of times. For example the code shown gets the user input, as long as the user inserts numbers which are not 0. If the user inserts 0, the ...

In certain cases we need to cancel an image download request in Picasso before the download has completed. This could happen for various reasons, for example if the parent view transitioned to some other view before the image download could be completed. In this case, you can cancel the image down...

AsyncTask is an abstract Class and does not inherit the Thread class. It has an abstract method doInBackground(Params... params), which is overridden to perform the task. This method is called from AsyncTask.call(). Executor are part of java.util.concurrent package. Moreover, AsyncTask contains 2 ...

Unlike for and while loops, do-while loops check the truth of the condition at the end of the loop, which means the do block will execute once, and then check the condition of the while at the bottom of the block. Meaning that a do-while loop will always run at least once. For example this do-while...

DocumentDB supports deleting JSON documents using the DeleteDocumentAsync method of the DocumentClient class. await client.DeleteDocumentAsync(UriFactory.CreateDocumentUri(databaseName, collectionName, documentName));

Deleting a database will remove the database and all children resources (collections, documents, etc.). await this.client.DeleteDatabaseAsync(UriFactory.CreateDatabaseUri(databaseName));

You can select the last day of month. SELECT (date_trunc('MONTH', ('201608'||'01')::date) + INTERVAL '1 MONTH - 1 day')::DATE; 201608 is replaceable with a variable.

The $Label variable can be used to display text defined in your custom labels. <apex:outputText value="{!$Label.Welcome_Message}" /> You can do formatting with labels as well. Suppose you have a custom label named Welcome_Message defined as Welcome to our site, {0}! You could...

In a single IF..ELSE statement, if the expression evaluates to True in the IF statement the control enters the first BEGIN..END block and only the code inside that block gets executed , Else block is simply ignored. On the other hand if the expression evaluates to False the ELSE BEGIN..END block ge...

If we have Multiple IF...ELSE IF statements but we also want also want to execute some piece of code if none of expressions are evaluated to True , then we can simple add a final ELSE block which only gets executed if none of the IF or ELSE IF expressions are evaluated to true. In the example below...

More often than not we need to check multiple expressions and take specific actions based on those expressions. This situation is handled using multiple IF...ELSE IF statements. In this example all the expressions are evaluated from top to bottom. As soon as an expression evaluates to true, the cod...

It is convenient to set custom conditional preprocessing at project level when some actions need to be skipped lets say for tests. Go to Solution Explorer -> Click Right Mouse on project you want to set variable to -> Properties -> Build -> In General find field Conditional compilation ...

C# Suppose you want to test that when you hover over an element, a drop list is displayed. You may want to check the contents of this list, or perhaps select an option from the list. First create an Action, to hover over the element (e.g. my element has link text "Admin"): Actions mouse...

A Haskell's Functor allows one to map any type a (an object of Hask) to a type F a and also map a function a -> b (a morphism of Hask) to a function with type F a -> F b. This corresponds to a Category Theory definition in a sense that functor preserves basic category structure. A monoidal ca...

In this example we create a new list element with the text "new text", and select the first unordered list, and its first list element. let newElement = document.createElement("li"); newElement.innerHTML = "new text"; let parentElement = document.querySelector(&quo...

In this example we create a new list element with the text "new text", and select the first unordered list, and its first list element. let newElement = document.createElement("li"); newElement.innerHTML = "new text"; let parentElement = document.querySelector(&quo...