Tutorial by Examples: io

Some LINQ methods return a query object. This object does not hold the results of the query; instead, it has all the information needed to generate those results: var list = new List<int>() {1, 2, 3, 4, 5}; var query = list.Select(x => { Console.Write($"{x} "); return ...

To show and hide a FloatingActionButton with the default animation, just call the methods show() and hide(). It's good practice to keep a FloatingActionButton in the Activity layout instead of putting it in a Fragment, this allows the default animations to work when showing and hiding. Here is an ...

In general, functions that operate on other functions, either by taking them as arguments or by returning them (or both), are called higher-order functions. A higher-order function is a function that can take another function as an argument. You are using higher-order functions when passing callbac...

class CreateAuthenticationProviders < ActiveRecord::Migration def change create_table "authentication_providers", :force => true do |t| t.string "name" t.datetime "created_at", :null => false ...

class CreateUserAuthentications < ActiveRecord::Migration def change create_table "user_authentications", :force => true do |t| t.integer "user_id" t.integer "authentication_provider_id" t.string "uid&q...

has_many :users has_many :user_authentications

belongs_to :user belongs_to :authentication_provider serialize :params def self.create_from_omniauth(params, user, provider) token_expires_at = params['credentials']['expires_at'] ? Time.at(params['credentials']['expires_at']).to_datetime : nil create( user: user, ...

The System.Web.SessionState.HttpSessionState object provides a way to persist values between HTTP requests. In the example below, a user's preference for warnings is being saved in the session. Later on, while serving another request to the user, the application can read this preference from session...

If you find that you have multiple servers that need to share session state, storing it in the ASP.NET process memory will not work. For example you may deploy into a web-farm environment with a load balancer that distributes requests in a round-robin fashion. In this environment a single user's req...

If you don't want to use SQL server you can use Amazon's hosted Dynamo DB nosql database as a session store. You'll need the AWS SDK. To install this from the Visual Studio nuget package manager console use the following command Install-Package AWSSDK You can then configure your sessionState p...

This is a copy of the advanced function snippet from the Powershell ISE. Basically this is a template for many of the things you can use with advanced functions in Powershell. Key points to note: get-help integration - the beginning of the function contains a comment block that is set up to be ...

SELECT department, COUNT(*) AS "Man_Power" FROM employees GROUP BY department;

Example of calling an extension method as an extension and as a regular method. public Class MyClass Sub Main() 'Extension called directly on the object. Dim Version = Assembly.GetExecutingAssembly.GetVersionFromAssembly() 'Called as a regular method. ...

Create a Dictionary<TKey, TValue> from an IEnumerable<T>: using System; using System.Collections.Generic; using System.Linq; public class Fruits { public int Id { get; set; } public string Name { get; set; } } var fruits = new[] { new Fruits { Id = 8 , Nam...

When allocating multidimensional arrays with malloc, calloc, and realloc, a common pattern is to allocate the inner arrays with multiple calls (even if the call only appears once, it may be in a loop): /* Could also be `int **` with malloc used to allocate outer array. */ int *array[4]; int i; ...

So far, we have looked at inserting a node at the beginning of a singly linked list. However, most of the times you will want to be able to insert nodes elsewhere as well. The code written below shows how it is possible to write an insert() function to insert nodes anywhere in the linked lists. #...

To be able to debug an application is very important to understand the flow of an application's logic and data. It helps solving logical bugs and adds value to the programming experience and code quality. Two popular gems for debugging are debugger (for ruby 1.9.2 and 1.9.3) and byebug (for ruby &g...

When adding a LIMIT to a UNION, this is the pattern to use: ( SELECT ... ORDER BY x LIMIT 10 ) UNION ( SELECT ... ORDER BY x LIMIT 10 ) ORDER BY x LIMIT 10 Since you cannot predict which SELECT(s) will the "10" will come from, you need to get 10 from each, then further whittle do...

To create a parallel collection from a sequential collection, call the par method. To create a sequential collection from a parallel collection, call the seq method. This example shows how you turn a regular Vector into a ParVector, and then back again: scala> val vect = (1 to 5).toVector vect:...

Detailed instructions on getting dropwizard set up or installed.