Tutorial by Examples: c

Meteor.call(name, [arg1, arg2...], [asyncCallback]) (1) name String (2) Name of method to invoke (3) arg1, arg2... EJSON-able Object [Optional] (4) asyncCallback Function [Optional] On one hand, you can do : (via Session variable, or via ReactiveVar) var syncCall = Meteor.call("my...

Create Table mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2)); Query OK, 0 rows affected (0.03 sec) Create Trigger mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account -> FOR EACH ROW SET @sum = @sum + NEW.amount; Query OK, 0 rows affected (0.06 sec) The CRE...

Prefer dict.get method if you are not sure if the key is present. It allows you to return a default value if key is not found. The traditional method dict[key] would raise a KeyError exception. Rather than doing def add_student(): try: students['count'] += 1 except KeyError: ...

Create a model (lets call it User) by running: $ rails g model User which will generate the file app/models/user.rb: class User include Mongoid::Document end This is all you need to have a model (albeit nothing but an id field). Unlike ActiveRecord, there is no migration files. All the...

Mongoid allows the classic ActiveRecord associations: One-to-one: has_one / belongs_to One-to-many: has_many / belongs_to Many-to-many: has_and_belongs_to_many To add an association (lets say the User has_many posts), you can add this to your User model file: has_many :posts and this to ...

Mongoid allows Embedded Associations: One-to-one: embeds_one / embedded_in One-to-many: embeds_many / embedded_in To add an association (lets say the User embeds_many addresses), add this to your User file: embeds_many :addresses and this to your Address model file: embedded_in :user ...

Mongoid tries to have similar syntax to ActiveRecord when it can. It supports these calls (and many more) User.first #Gets first user from the database User.count #Gets the count of all users from the database User.find(params[:id]) #Returns the user with the id found in params[:id] User.w...

The first thing you need to know when structuring your apps is that the Meteor tool has some directories that are hard-coded with specific logic. At a very basic level, the following directories are "baked in" the Meteor bundler. client/ # client applicati...

Many people find themselves eventually supporting multiple applications, and desire to share code between apps. This leads to the concept of microservice architecture, and all-package apps. Essentially, the code from the entire classic directory structure is refactored out into packages. Even tho...

The most recent versions of Meteor ship with support for ecmascript, aka ES6 or ES2015. Instead of packages, Javascript now supports import statements and modules, which replaces the need for package-only applications. The latest directory structure is similar to the package-only structure, but us...

And, of course, you can mix these approaches, and use both packages and imports along side your application specific code. A mix-mode structure is most common in three situations: a franken-app, which is just sort of pulling a bit from here-and-there without any overall strategy; an app that's bei...

#include <iostream> #include <functional> using std::placeholders::_1; // to be used in std::bind example int stdf_foobar (int x, std::function<int(int)> moo) { return x + moo(x); // std::function moo called } int foo (int x) { return 2+x; } int foo_2 (int x, in...

MySQL does not provide a built-in way to create pivot queries. However, these can be created using prepared statements. Assume the table tbl_values: IdNameGroupValue1PeteA102PeteB203JohnA10 Request: Create a query that shows the sum of Value for each Name; the Group must be column header and Name...

1) Create a Contract Class A contract class defines constants that help applications work with the content URIs, column names, intent actions, and other features of a content provider. Contract classes are not included automatically with a provider; the provider's developer has to define them and t...

globalize gem is a great solution to add translations to your ActiveRecord models. You can install it adding this to your Gemfile: gem 'globalize', '~> 5.0.0' If you're using Rails 5 you will also need to add activemodel-serializers-xml gem 'activemodel-serializers-xml' Model translations...

Due to type erasure the following will not work: public <T> void genericMethod() { T t = new T(); // Can not instantiate the type T. } The type T is erased. Since, at runtime, the JVM does not know what T originally was, it does not know which constructor to call. Workarounds ...

When an HTTP server receives a well-formed HTTP request, it must process the information that request contains and return a response to the client. A simple HTTP 1.1 response, may look like any of the following, usually followed by a number of header fields, and possibly a response body: HTTP/1.1 2...

DELETE FROM `myTable` WHERE `someColumn` = 'something' The WHERE clause is optional but without it all rows are deleted.

A common problem is having a collection of items that all need to meet a certain criteria. In the example below we have collected two items for a diet plan and we want to check that the diet doesn't contain any unhealthy food. // First we create a collection $diet = collect([ ['name' => ...

You will often find yourself with a collection of data where you are only interested in parts of the data. In the example below we got a list of participants at an event and we want to provide a the tour guide with a simple list of names. // First we collect the participants $participants = colle...