Tutorial by Examples: p

The following example shows the declaration of a property (StringProperty in this case) and demonstrates how to add a ChangeListener to it. import java.text.MessageFormat; import javafx.beans.property.SimpleStringProperty; import javafx.beans.property.StringProperty; import javafx.beans.value.Ch...

This example shows how to use a readonly wrapper property to create a property that cannot be written to. In this case cost and price can be modified, but profit will always be price - cost. import java.text.MessageFormat; import javafx.beans.property.IntegerProperty; import javafx.beans.property...

The following example remaps the key Z to Y and vice versa, e.g. if you want to work with the QWERTY layout on a QWERTZ keyboard. z::y y::z

Overall the easiest way to work with JSON is to have a case class mapping directly to the JSON (same fields name, equivalent types, etc.). case class Person( name: String, age: Int, hobbies: Seq[String], pet: Pet ) case class Pet( name: String, `type`: String ) // these...

Summary: MVVM is an architectural pattern that is represented by three distinct components, the Model, View and ViewModel. In order to understand these three layers, it is necessary to briefly define each, followed by an explanation of how they work together. Model is the layer that drives the bus...

qmake is a build automation tool, which is shipped with Qt framework. It does similar job to tools such as CMake or GNU Autotools, but it is designed to be used specifically with Qt. As such it is well integrated with Qt ecosystem, notably Qt Creator IDE. If you start Qt Creator and select File -&g...

If we want to replace only the first occurrence in a line, we use sed as usual: $ cat example aaaaabbbbb aaaaaccccc aaaaaddddd $ sed 's/a/x/' example xaaaabbbbb xaaaaccccc xaaaaddddd But what if we want to replace all occurrences? We just add the g pattern flag at the end: $ sed 's/a/x/...

A form gives the user a way to change data in your application, in a structured way. To mutate a simple array of data, we create a form using a form builder: use Symfony\Component\Form\Extension\Core\Type\TextType; use Symfony\Component\Form\Extension\Core\Type\NumberType; use Symfony\Component\F...

A custom form type is a class which defines a reusable form component. Custom form components can be nested to create complicated forms. Instead of creating a form in the controller using a form builder, you can use your own type to make the code more readable, reusable and maintanable. Create a c...

manifest.json { "name": "Hello Page", "description": "Add 'Hello' to the current page.", "version": "1.0", "permissions": [ "activeTab" ], "background": { "scripts": [&quo...

Postgresql-simple is a mid-level Haskell library for communicating with a PostgreSQL backend database. It is very simple to use and provides a type-safe API for reading/writing to a DB. Running a simple query is as easy as: {-# LANGUAGE OverloadedStrings #-} import Database.PostgreSQL.Simple ...

It is possible to define a data type with field labels. data Person = Person { age :: Int, name :: String } This definition differs from a normal record definition as it also defines *record accessors which can be used to access parts of a data type. In this example, two record accessors are de...

One of the most common obstacles using classes is finding the proper approach to handle private states. There are 4 common solutions for handling private states: Using Symbols Symbols are new primitive type introduced on in ES2015, as defined at MDN A symbol is a unique and immutable data typ...

To Copy Data from a CSV file to a table COPY <tablename> FROM '<filename with path>'; To insert into table user from a file named user_data.csv placed inside /home/user/: COPY user FROM '/home/user/user_data.csv'; To Copy data from pipe separated file to table COPY user FROM '/h...

To Copy table to standard o/p COPY <tablename> TO STDOUT (DELIMITER '|'); To export table user to Standard ouput: COPY user TO STDOUT (DELIMITER '|'); To Copy table to file COPY user FROM '/home/user/user_data' WITH DELIMITER '|'; To Copy the output of SQL statement to file COPY (sql st...

Data can be exported using copy command or by taking use of command line options of psql command. To Export csv data from table user to csv file: psql -p \<port> -U \<username> -d \<database> -A -F<delimiter> -c\<sql to execute> \> \<output filename with path&gt...

Opening a database is an asynchronous operation. We need to send a request to open our database and then listen for events so we know when it's ready. We'll open a DemoDB database. If it doesn't exist yet, it will get created when we send the request. The 2 below says that we're asking for version...

In HBase, you can use 4 types of operations Get : retrieves a row Put : inserts one or more row(s) Delete : delete a row Scan : retrieves several rows If you simply want to retrieve a row, given its row_key you can use the Get object: Get get = new Get(Bytes.toBytes("my_row_key")...

Click Right Mouse on Database you want to migrate then -> Tasks -> Generate Scripts... Wizard will open click Next then chose objects you want to migrate and click Next again, then click Advanced scroll a bit down and in Types of data to script choose Schema and data (unless you want ...

console.dir(object) displays an interactive list of the properties of the specified JavaScript object. The output is presented as a hierarchical listing with disclosure triangles that let you see the contents of child objects. var myObject = { "foo":{ "bar":"d...