Tutorial by Examples: n

Route constraints let you restrict how the parameters in the route template are matched. The general syntax is {parameter:constraint}. For example: // eg: /users/5 [Route(“users/{id:int}”] public ActionResult GetUserById(int id) { … } // eg: users/ken [Route(“users/{name}”] public ActionRes...

Pretext This is an introduction to the Hello World program example on the Raspberry Pi written in C. The following example makes use of the command line interface and is set up as a step-by-step guide. Along with creating a Hello World program, the reader will be introduced to simple linux comman...

Sending data back to the parent, to do this we simply pass a function as a prop from the parent component to the child component, and the child component calls that function. In this example, we will change the Parent state by passing a function to the Child component and invoking that function ins...

Another way of doing aggregations is by using the Mongo.Collection#rawCollection() This can only be run on the Server. Here is an example you can use in Meteor 1.3 and higher: Meteor.methods({ 'aggregateUsers'(someId) { const collection = MyCollection.rawCollection() const aggre...

Logs are very important. Recreate an error context can be sometimes very painful due to the lack of information about how and when the error occurred. This example shows: How to add user's data in the error logs How to add post parameters sent when an error occurred How to use WebPr...

Use Nuget to install the Nancy and Nancy.Hosting.Self packages into the project. Instantiate a new NancyHost object and pass in the relevant URL using( var host = new NancyHost( hostConfiguration, new Uri( "http://localhost:1234" ) ) ) { host.Start(); Console.WriteLine( "Running o...

When you want to work with the data entries in arrays you first need to unwind the array. The unwind operation creates a document for each entry in the array. When you have lot's of documents with large arrays you will see an explosion in number of documents. { "_id" : 1, "item"...

_refreshControl(){ return ( <RefreshControl refreshing={this.state.refreshing} onRefresh={()=>this._refreshListView()} /> ) } refreshing: is the state of the spinner (true, false). onRefresh: this function will invoke when refresh the ListView/Scr...

_refreshListView(){ //Start Rendering Spinner this.setState({refreshing:true}) this.state.cars.push( {name:'Fusion',color:'Black'}, {name:'Yaris',color:'Blue'} ) //Updating the dataSource with new data this.setState({ dataSource: this.state.data...

RefreshControl is used inside a ScrollView or ListView to add pull to refresh functionality. at this example we will use it with ListView 'use strict' import React, { Component } from 'react'; import { StyleSheet, View, ListView, RefreshControl, Text } from 'react-native' class RefreshContr...

//Before: antipattern 3 global variables var setActivePage = function () {}; var getPage = function() {}; var redirectPage = function() {}; //After: just 1 global variable, no function collision and more meaningful function names var NavigationNs = NavigationNs || {}; N...

When multiple modules are involved, avoid proliferating global names by creating a single global namespace. From there, any sub-modules can be added to the global namespace. (Further nesting will slow down performance and add unnecessary complexity.) Longer names can be used if name clashes are an i...

Let us assume we have the following two DataFrames: In [7]: df1 Out[7]: A B 0 a1 b1 1 a2 b2 In [8]: df2 Out[8]: B C 0 b1 c1 The two DataFrames are not required to have the same set of columns. The append method does not change either of the original DataFrames. Inst...

You can quickly determine if a text includes a specific pattern using Regex. There are multiple ways to work with Regex in PowerShell. #Sample text $text = @" This is (a) sample text, this is a (sample text) "@ #Sample pattern: Content wrapped in () $pattern = '\(.*?\)' Using ...

Sometimes you need to replace a value matching a pattern with a new value that's based on that specific match, making it impossible to predict the new value. For these types of scenarios, a MatchEvaluator can be very useful. In PowerShell, a MatchEvaluator is as simple as a scriptblock with a singl...

You can delete existing snapshots of database using DELETE DATABASE statement: DROP DATABASE Mydatabase_morning In this statement you should reference name of the database snapshot.

Tuples are immutable ordered collections of arbitrary distinct objects, either of the same type or of different types. Typically, tuples are constructed using the (x, y) syntax. julia> tup = (1, 1.0, "Hello, World!") (1,1.0,"Hello, World!") The individual objects of a tup...

Because Julia function parameter lists are themselves tuples, dispatching on various kinds of tuples is often easier done through the method parameters themselves, often with liberal usage for the "splatting" ... operator. For instance, consider the implementation of reverse for tuples, fr...

Tuples are frequently used for multiple return values. Much of the standard library, including two of the functions of the iterable interface (next and done), returns tuples containing two related but distinct values. The parentheses around tuples can be omitted in certain situations, making multip...

The IIF statement can be used in expressions to screen for division by zero: =IIF(Fields!PossibleZero.Value=0,0,Fields!Denominator.Value/IIF(Fields!PossibleZero.Value=0,1,Fields!PossibleZero.Value)) SSRS does not short circuit IIF arguments. Therefore, using a single IIF function to screen for ...