Tutorial by Examples: ch

We will look at a simple dispatch event with the example usage. (ns myapp.events (:require [re-frame.core :refer [reg-event-db]])) ...

ChainMap is new in version 3.3 Returns a new ChainMap object given a number of maps. This object groups multiple dicts or other mappings together to create a single, updateable view. ChainMaps are useful managing nested contexts and overlays. An example in the python world is found in the implemen...

First of all, watch out which analyzer you are using. I was stumped for a while only to realise that the StandardAnalyzer filters out common words like 'the' and 'a'. This is a problem when your field has the value 'A'. You might want to consider the KeywordAnalyzer: See this post around the analyz...

Then we finally pass the query to the writer to delete documents that match the query: See the answer to this question. See the API here // Remove the document by using a multi key query: // http://www.avajava.com/tutorials/lessons/how-do-i-combine-queries-with-a-boolean-query.html indexWriter....

step 1: Create Project - Application - app.js - Controllers - appController.js - Factories - SignalR-factory.js - index.html - Scripts - angular.js - jquery.js - jquery.signalR.min.js - Hubs SignalR version use: signalR-2.2.1 Step 2: Startu...

You get this exception mostly with form submissions. Laravel protects application from CSRF and validates every request and ensures the request originated from within the application. This validation is done using a token. If this token mismatches this exception is generated. Quick Fix Add this wi...

In order to chain asynchronous operations and avoid a callback hell, Vala supports the yield statement. Used with an asynchronous invocation, it will pause the current coroutine until the call is completed and extract the result. Used alone, yield pause the current coroutine until it's being woken...

class ConversationsTableViewController: UITableViewController, NSFetchedResultsControllerDelegate { private var fetchedResultsController: NSFetchedResultsController<Conversation>! override func viewDidLoad() { super.viewDidLoad() initializeFetchedResultsController() } private...

Two definitions of Machine Learning are offered. Arthur Samuel described it as: the field of study that gives computers the ability to learn without being explicitly programmed. This is an older, informal definition. Tom Mitchell provides a more modern definition: A computer program is sa...

To get started, create a new Maven webapp (how to do this is outside the scope of this example). In your pom.xml, add the following two dependencies <dependency> <groupId>org.glassfish.jersey.containers</groupId> <artifactId>jersey-container-servlet</artifactId&...

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...

Prerequisites : ChromeDriver is downloaded Copy the following code into your class. public static void main(String[] args) { System.setProperty("webdriver.chrome.driver", "path of the exe file\\chromedriver.exe"); } If you're using linux, give the path to the ChromeDri...

What Are Notification Channels? Notification channels enable us app developers to group our notifications into groups—channels—with the user having the ability to modify notification settings for the entire channel at once. For example, for each channel, users can completely block all notifications...

Once you are connected to a Gatt Server, you're going to be interacting with it by writing and reading from the server's characteristics. To do this, first you have to discover what services are available on this server and which characteristics are avaiable in each service: @Override public voi...

You can select a branch at the upper left. When you selected the right branch you need to press the sync button (upper right) which does now the same as git checkout BRANCHNAME. In the older version you are able to view 2 different branches at once and compare the pushes. Furthermore you could vi...

Search engine optimization (SEO for short) is simply the process of obtaining website visitors (or traffic) from “free” or “organic” search results in search engines like Google or Bing. All major search engines have primary search results that are ranked based on what the search engine considers m...

If you have: infix fun <T> T?.shouldBe(expected: T?) = assertEquals(expected, this) you can write the following DSL-like code in your tests: @Test fun test() { 100.plusOne() shouldBe 101 }

A common problem might be trying to iterate over Array which has no values in it. For example: Dim myArray() As Integer For i = 0 To UBound(myArray) 'Will result in a "Subscript Out of Range" error To avoid this issue, and to check if an Array contains elements, use this oneliner: If...

Create a file (e.g. hello_world.py) in a text editor or a python editor if you have one installed (pick one if you don't - SublimeText, Eclipse, NetBeans, SciTe... there's many!) hwld = 'Hello world' print(hwld) Note that python variables do not need to be explicitly declared; the declaration h...

If you have a multidimensional array like this: [ ['foo', 'bar'], ['fizz', 'buzz'], ] And you want to change it to an associative array like this: [ 'foo' => 'bar', 'fizz' => 'buzz', ] You can use this code: $multidimensionalArray = [ ['foo', 'bar'], ...