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Create a class inheriting from Exception: class FooException(Exception): pass try: raise FooException("insert description here") except FooException: print("A FooException was raised.") or another exception type: class NegativeError(ValueError): pass ...

Flask has a utility called jsonify() that makes it more convenient to return JSON responses from flask import Flask, jsonify app = Flask(__name__) @app.route('/api/get-json') def hello(): return jsonify(hello='world') # Returns HTTP Response with {"hello": "world"} ...

If the mimetype of the HTTP request is application/json, calling request.get_json() will return the parsed JSON data (otherwise it returns None) from flask import Flask, jsonify app = Flask(__name__) @app.route('/api/echo-json', methods=['GET', 'POST', 'DELETE', 'PUT']) ...

Python minimally evaluates Boolean expressions. >>> def true_func(): ... print("true_func()") ... return True ... >>> def false_func(): ... print("false_func()") ... return False ... >>> true_func() or false_func() true_func(...

public void iterateAndFilter() throws IOException { Path dir = Paths.get("C:/foo/bar"); PathMatcher imageFileMatcher = FileSystems.getDefault().getPathMatcher( "regex:.*(?i:jpg|jpeg|png|gif|bmp|jpe|jfif)"); try (Direc...

# For Python 2 compatibility. from __future__ import print_function import lxml.html import requests def main(): r = requests.get("https://httpbin.org") html_source = r.text root_element = lxml.html.fromstring(html_source) # Note root_element.xpath() gives a *...

Given a String and a Character let text = "Hello World" let char: Character = "o" We can count the number of times the Character appears into the String using let sensitiveCount = text.characters.filter { $0 == char }.count // case-sensitive let insensitiveCount = text.low...

Add gem to the Gemfile: gem 'devise' Then run the bundle install command. Use command $ rails generate devise:install to generate required configuration file. Set up the default URL options for the Devise mailer in each environment In development environment add this line: config.action_mailer...

Boolean(0) === false Boolean(0) will convert the number 0 into a boolean false. A shorter, but less clear, form: !!0 === false

To convert a string to boolean use Boolean(myString) or the shorter but less clear form !!myString All strings except the empty string (of length zero) are evaluated to true as booleans. Boolean('') === false // is true Boolean("") === false // is true Boolean('0') === fals...

If the values in a container have certain operators already overloaded, std::sort can be used with specialized functors to sort in either ascending or descending order: C++11 #include <vector> #include <algorithm> #include <functional> std::vector<int> v = {5,1,2,4,3};...

If you have created a table with some wrong schema, then the easiest way to change the columns and their properties is change_table. Review the following example: change_table :orders do |t| t.remove :ordered_at # removes column ordered_at t.string :skew_number # adds a new column t.index...

Managed resources are resources that the runtime's garbage collector is aware and under control of. There are many classes available in the BCL, for example, such as a SqlConnection that is a wrapper class for an unmanaged resource. These classes already implement the IDisposable interface -- it's u...

It's important to let finalization ignore managed resources. The finalizer runs on another thread -- it's possible that the managed objects don't exist anymore by the time the finalizer runs. Implementing a protected Dispose(bool) method is a common practice to ensure managed resources do not have t...

You can add a home page route to your app with the root method. # config/routes.rb Rails.application.routes.draw do root "application#index" # equivalent to: # get "/", "application#index" end # app/controllers/application_controller.rb class Applicati...

Iterating over List List<String> names = new ArrayList<>(Arrays.asList("Clementine", "Duran", "Mike")); Java SE 8 names.forEach(System.out::println); If we need parallelism use names.parallelStream().forEach(System.out::println); Java SE 5 fo...

When a controller action is rendered, Rails will attempt to find a matching layout and view based on the name of the controller. Views and layouts are placed in the app/views directory. Given a request to the PeopleController#index action, Rails will search for: the layout called people in app/...

class UsersController < ApplicationController def index hashmap_or_array = [{ name: "foo", email: "[email protected]" }] respond_to do |format| format.html { render html: "Hello World" } format.json { render json: hashmap_or_array } en...

class UsersController < ApplicationController def index respond_to do |format| format.html { render html: "Hello World" } end end end This is a basic controller, with the addition of the following route (in routes.rb): resources :users, only: [:index] Will...

Controllers have access to HTTP parameters (you might know them as ?name=foo in URLs, but Ruby on Rails handle different formats too!) and output different responses based on them. There isn't a way to distinguish between GET and POST parameters, but you shouldn't do that in any case. class UsersCo...