Tutorial by Examples: s

ActiveRecord with includes ensures that all of the specified associations are loaded using the minimum possible number of queries. So when querying a table for data with an associated table, both tables are loaded into memory. @authors = Author.includes(:books).where(books: { bestseller: true } ) ...

Given a class as follows: class Cube attr_reader :height, :width, :depth def initialize(args) @height = args[:height] || args[:y] || 1 @width = args[:width] || args[:x] || 1 @depth = args[:depth] || args[:z] || 1 end def volume height * width * depth end ...

In PHP, there are two versions of logical AND and OR operators. OperatorTrue if$a and $bBoth $a and $b are true$a && $bBoth $a and $b are true$a or $bEither $a or $b is true$a || $bEither $a or $b is true Note that the && and || opererators have higher precedence than and and or. S...

In cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can access it. Source: Encryption - Wikipedia

Imagine that we have a separate Google spreadsheet, and we need to get the B2 cell value to cell D5 on your current sheet. function copyValueandPaste() { var source = SpreadsheetApp.openById('spread sheet id is here'); //Separate spreadsheet book var sourcesheet = source.getSheetByName...

As with docopt, with [docopt_dispatch] you craft your --help in the __doc__ variable of your entry-point module. There, you call dispatch with the doc string as argument, so it can run the parser over it. That being done, instead of handling manually the arguments (which usually ends up in a high c...

Functions that are O(n) increase the number of operations linearly, as the input gets very large. A simple example of a function that is O(n) would be the linear search algorithm, which runs once for the size of the input. The following pseudo-code would be O(n), because it will always be bounded ...

We can add Kendo-UI grid in HTML5/Javascript, ASP.NET MVC, JSP and PHP project/application. Please follow below steps to add kendo-UI grid in HTML5 page. Create empty html5 page. Include kendo.common.min.css and kendo.default.min.css. Add a link tag within the head tag. Kendo-UI li...

The following example shows how to use a QTimer to call a slot every 1 second. In the example, we use a QProgressBar to update its value and check the timer is working properly. main.cpp #include <QApplication> #include "timer.h" int main(int argc, char *argv[]) { QApp...

Consider the following naive method for adding two positive numbers using recursion: public static int add(int a, int b) { if (a == 0) { return b; } else { return add(a - 1, b + 1); // TAIL CALL } } This is algorithmically correct, but it has a major problem. ...

Manually open and close a file. # Using new method f = File.new("test.txt", "r") # reading f = File.new("test.txt", "w") # writing f = File.new("test.txt", "a") # appending # Using open method f = open("test.txt", "r&...

The Chef documentation can be found at https://docs.chef.io/

For immutable elements (e.g. None, string literals etc.): my_list = [None] * 10 my_list = ['test'] * 10 For mutable elements, the same construct will result in all elements of the list referring to the same object, for example, for a set: >>> my_list=[{1}] * 10 >>> print(my_...

General syntax: DATEADD (datepart , number , datetime_expr) To add a time measure, the number must be positive. To subtract a time measure, the number must be negative. Examples DECLARE @now DATETIME2 = GETDATE(); SELECT @now; --2016-07-21 14:39:46.4170000 SELECT DAT...

These are the datepart values available to date & time functions: datepartAbbreviationsyearyy, yyyyquarterqq, qmonthmm, mdayofyeardy, ydaydd, dweekwk, wwweekdaydw, whourhhminutemi, nsecondss, smillisecondmsmicrosecondmcsnanosecondns NOTE: Use of abbreviations is generally discouraged as they c...

General syntax: DATEDIFF (datepart, datetime_expr1, datetime_expr2) It will return a positive number if datetime_expr is in the past relative to datetime_expr2, and a negative number otherwise. Examples DECLARE @now DATETIME2 = GETDATE(); DECLARE @oneYearAgo DATETIME2 = DATEADD(YEAR, -1, @now...

Using the DATEADD and DATEDIFF functions, it's possible to return the last date of a month. SELECT DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, '2016-09-23') + 1, 0)) -- 2016-09-30 00:00:00.000 SQL Server 2012 The EOMONTH function provides a more concise way to return the last date of a month, and...

Sometimes when destructuring maps, you would like to bind the destructured values to their respective key name. Depending on the granularity of the data structure, using the standard destructuring scheme may be a little bit verbose. Let's say, we have a map based record like so : (def john {:lastn...

One approach that is employed often is to use bootstrap's gridded framework in order to define the area that the chart will exist in. Using this in conjunction with clientWidth variable and the window.onresize event, it is very easy to create responsive d3 SVGs. Let's first create a row and a colum...

A CSS rule consists of a selector (e.g. h1) and declaration block ({}). h1 {}