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We can check the status of migrations by running 3.05.0 rake db:migrate:status 5.0 rails db:migrate:status The output will look like this: Status Migration ID Migration Name -------------------------------------------------- up 20140711185212 Create documentation pages up ...

Rails.cache, provided by ActiveSupport, can be used to cache any serializable Ruby object across requests. To fetch a value from the cache for a given key, use cache.read: Rails.cache.read('city') # => nil Use cache.write to write a value to the cache: Rails.cache.write('city', 'Duckburgh'...

You can use the ActionPack page_caching gem to cache individual pages. This stores the result of one dynamic request as a static HTML file, which is served in place of the dynamic request on subsequent requests. The README contains full setup instructions. Once set up, use the caches_page class meth...

Rails >= 3 comes with HTTP caching abilities out of the box. This uses the Cache-Control and ETag headers to control how long a client or intermediary (such as a CDN) can cache a page. In a controller action, use expires_in to set the length of caching for that action: def show @user = User....

GCD will guarantee that your singleton only gets instantiated once, even if called from multiple threads. Insert this into any class for a singleton instance called shared. + (instancetype)shared { // Variable that will point to the singleton instance. The `static` // modifier makes it ...

Given a file file.txt with the following content: line 1 line 2 line 3 You can add a new line after first matching line with the a command. For portable use the a command must be followed immediately by an escaped newline, with the text-to-append on its own line or lines. sed ' /line 2/a\ ...

Consumable Managed Products are products that can be bought multiple times such as in-game currency, game lives, power-ups, etc. In this example, we are going to implement 4 different consumable managed products "item1", "item2", "item3", "item4". Steps in...

Any lodash collection method has two syntaxes. Without chaining: var arr1 = [10, 15, 20, 25, 30, 15, 25, 35]; var arr2 = _.filter(arr1, function(item){ return item % 10 === 5 }); // arr2 now contains [15, 25, 15, 25, 35] var arr3 = _.uniq(arr2); // arr3 now contains [15, 25, 35] var arr...

To check if a given value exists in a set, use .has() method: mySet.has(someVal); Will return true if someVal appears in the set, false otherwise.

One is able to nest one exception / try catch block inside the other. This way one can manage small blocks of code which are capable of working without disrupting your whole mechanism. try { //some code here try { //some thing which throws an exception. For Eg : divide by 0 ...

1) Form Request Validation You may create a "form request" which can hold the authorization logic, validation rules, and error messages for a particular request in your application. The make:request Artisan CLI command generates the class and places it in the app/Http/Requests director...

brew install mpich

Type erasure is a way to hide the type of an object from code using it, even though it is not derived from a common base class. In doing so, it provides a bridge between the worlds of static polymorphism (templates; at the place of use, the exact type must be known at compile time, but it need not b...

.message color: white background: black .message-important @extend .message font-weight: bold .message-error @extend .message-important font-style: italic This code causes .message-error to extend from .message-important, which means that it will contain code from both .me...

The pattern matching library trivia provides a system trivia.ppcre that allows captured groups to be bound through pattern matching (trivia:match "John Doe" ((trivia.ppcre:ppcre "(.*)\\W+(.*)" first-name last-name) (list :first-name first-name :last-name last-name))) ;...

redis-cli ping This should return PONG

When to use An attached property is a dependency property that can be applied to any DependencyObject to enhance the behavior of various controls or services that are aware of the property's existence. Some use cases for attached properties include: Having a parent element iterate through its c...

article.twig.html <article> <h1>{{ article.title }}</h1> {% block content %} <p>{{ article.content }}</p> {% endblock %} </article> articles.twig.html {# use default template for article #} {% for article in articles %} {% include &...

In this case, "monkey patching" means adding a new variable or method to a class after it's been defined. For instance, say we defined class A as class A(object): def __init__(self, num): self.num = num def __add__(self, other): return A(self.num + other.num)...

public static class ArrayHelpers { public static bool Contains<T>(this T[] array, T[] candidate) { if (IsEmptyLocate(array, candidate)) return false; if (candidate.Length > array.Length) return false; for (int a = 0; a <...