Tutorial by Examples: g

While using scaffolding is a fast and easy if you are new to Rails or you are creating a new application, later it can be useful just to do it on your own ato avoid the need to go through the scaffold-generated code to slim it down (remove unused parts, etc.). Creating a model can be as simple as c...

Ruby on Rails provides a model generator you can use to create ActiveRecord models. Simply use rails generate model and provide the model name. $ rails g model user In addition to the model file in app/models, the generator will also create: the Test in test/models/user_test.rb the Fixtures ...

This example requires the headers <algorithm>, <locale>, and <utility>. C++11 To trim a sequence or string means to remove all leading and trailing elements (or characters) matching a certain predicate. We first trim the trailing elements, because it doesn't involve moving any el...

Step 1: Open a Workbook Step 2 Option A: Press Alt + F11 This is the standard shortcut to open the VBE. Step 2 Option B: Developer Tab --> View Code First, the Developer Tab must be added to the ribbon. Go to File -> Options -> Customize Ribbon, then check the box for developer. ...

In Python 2, reduce is available either as a built-in function or from the functools package (version 2.6 onwards), whereas in Python 3 reduce is available only from functools. However the syntax for reduce in both Python2 and Python3 is the same and is reduce(function_to_reduce, list_to_reduce). A...

Errors thrown from promises are handled by the second parameter (reject) passed to then or by the handler passed to catch: throwErrorAsync() .then(null, error => { /* handle error here */ }); // or throwErrorAsync() .catch(error => { /* handle error here */ }); Chaining If you hav...

This example is a quick setup of Angular 2 and how to generate a quick example project. Prerequisites: Node.js v4 or greater. npm v3 or greater or yarn. Open a terminal and run the commands one by one: npm install -g @angular/cli or yarn global add @angular/cli depending on your choi...

The main difference is that double-quoted String literals support string interpolations and the full set of escape sequences. For instance, they can include arbitrary Ruby expressions via interpolation: # Single-quoted strings don't support interpolation puts 'Now is #{Time.now}' # Now is #{Time...

Ruby provides several ways to create a String object. The most common way is using single or double quotes to create a "string literal": s1 = 'Hello' s2 = "Hello" The main difference is that double-quoted string literals are a little bit more flexible as they support interpo...

Concatenate strings with the + operator: s1 = "Hello" s2 = " " s3 = "World" puts s1 + s2 + s3 # => Hello World s = s1 + s2 + s3 puts s # => Hello World Or with the << operator: s = 'Hello' s << ' ' s << 'World' puts s # => ...

The double-quoted delimiter " and %Q sequence supports string interpolation using #{ruby_expression}: puts "Now is #{Time.now}" # Now is Now is 2016-07-21 12:47:45 +0200 puts %Q(Now is #{Time.now}) # Now is Now is 2016-07-21 12:47:45 +0200

You can iterate over arrays either by using enhanced for loop (aka foreach) or by using array indices: int[] array = new int[10]; // using indices: read and write for (int i = 0; i < array.length; i++) { array[i] = i; } Java SE 5 // extended for: read only for (int e : array) { ...

Tuples are created using generic types Tuple<T1>-Tuple<T1,T2,T3,T4,T5,T6,T7,T8>. Each of the types represents a tuple containing 1 to 8 elements. Elements can be of different types. // tuple with 4 elements var tuple = new Tuple<string, int, bool, MyClass>("foo", 123, t...

To access tuple elements use Item1-Item8 properties. Only the properties with index number less or equal to tuple size are going to be available (i.e. one cannot access Item3 property in Tuple<T1,T2>). var tuple = new Tuple<string, int, bool, MyClass>("foo", 123, true, new MyC...

Some people have issues regarding error messages not being displayed if an existing value is being entered. For example I'm not allowing a user signup with an existing email. View <?php ...................... <?= $form->field($modelUser, 'email')->textInput(['class'=&gt...

Lets assume you have a class called Person with just name private class Person { public String name; public Person(String name) { this.name = name; } } Code: Gson g = new Gson(); Person person = new Person("John"); System.out.println(g.toJson(person)); /...

Lets assume you have a class called Person with just name private class Person { public String name; public Person(String name) { this.name = name; } } Code: Gson gson = new Gson(); String json = "{\"name\": \"John\"}"; Person person ...

String json = "{\"name\": \"John\", \"age\":21}"; JsonObject jsonObject = new JsonParser().parse(json).getAsJsonObject(); System.out.println(jsonObject.get("name").getAsString()); //John System.out.println(jsonObject.get("age").getAs...

In Python 2, range function returns a list while xrange creates a special xrange object, which is an immutable sequence, which unlike other built-in sequence types, doesn't support slicing and has neither index nor count methods: Python 2.x2.3 print(range(1, 10)) # Out: [1, 2, 3, 4, 5, 6, 7, 8, 9...

With any variadic function, the function must know how to interpret the variable arguments list. With the printf() or scanf() functions, the format string tells the function what to expect. The simplest technique is to pass an explicit count of the other arguments (which are normally all the same ...