Scopes act as predefined filters on ActiveRecord models.
A scope is defined using the scope class method.
As a simple example, we will use the following model:
class Person < ActiveRecord::Base
#attribute :first_name, :string
#attribute :last_name, :string
#attribute :age, :integer
...
Defining Strings in the strings.xml file also allows for string formatting. The only caveat is that the String will need to be dealt with in code like below, versus simply attaching it to a layout.
<string name="welcome_trainer">Hello Pokémon Trainer, %1$s! You have caught %2$d Poké...
Unlike C++ in C# you can call a virtual method from class constructor (OK, you can also in C++ but behavior at first is surprising). For example:
abstract class Base
{
protected Base()
{
_obj = CreateAnother();
}
protected virtual AnotherBase CreateAnother()
{
...
You can easily transform every component in a clickable button using the MouseArea component. The code below displays a 360x360 window with a button and a text in the center; pressing the button will change the text:
import QtQuick 2.0
Rectangle {
width: 360
height: 360
Rectang...
To find all the files of a certain extension within the current path you can use the following find syntax. It works by making use of bash's built-in glob construct to match all the names having the .extension.
find /directory/to/search -maxdepth 1 -type f -name "*.extension"
To find ...
Since Git 1.7.12 it is possible to rebase down to the root commit. The root commit is the first commit ever made in a repository, and normally cannot be edited. Use the following command:
git rebase -i --root
It is also possible to write a context manager using generator syntax thanks to the contextlib.contextmanager decorator:
import contextlib
@contextlib.contextmanager
def context_manager(num):
print('Enter')
yield num + 1
print('Exit')
with context_manager(2) as cm:
# the ...
Intents can be used to broadcast messages to other components of your application (such as a running background service) or to the entire Android system.
To send a broadcast within your application, use the LocalBroadcastManager class:
Intent intent = new Intent("com.example.YOUR_ACTION"...
TRUNCATE TABLE Employee;
Using truncate table is often better then using DELETE TABLE as it ignores all the indexes and triggers and just removes everything.
Delete table is a row based operation this means that each row is deleted. Truncate table is a data page operation the entire data page is...
To move data you first insert it into the target, then delete whatever you inserted from the source table. This is not a normal SQL operation but it may be enlightening
What did you insert? Normally in databases you need to have one or more columns that you can use to uniquely identify rows so we w...
It is a common practice to place multiple <div> inside another <div>. This is usually referred to as "nesting" elements and allows for further dividing elements into subsections or aid developers with CSS styling.
The <div class="outer-div"> is used to group to...
Since C# 6.0 exceptions can be filtered using the when operator.
This is similar to using a simple if but does not unwind the stack if the condition inside the when is not met.
Example
try
{
// ...
}
catch (Exception e) when (e.InnerException != null) // Any condition can go in here.
{
...
You can access SharedPreferences in several ways:
Get the default SharedPreferences file:
import android.preference.PreferenceManager;
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
Get a specific SharedPreferences file:
public static final String PREF_FILE_NAM...
The shift operators allow programmers to adjust an integer by shifting all of its bits to the left or the right. The following diagram shows the affect of shifting a value to the left by one digit.
Left-Shift
uint value = 15; // 00001111
uint doubled = value << 1; // Resu...
You can use the CONVERT function to cast a datetime datatype to a formatted string.
SELECT GETDATE() AS [Result] -- 2016-07-21 07:56:10.927
You can also use some built-in codes to convert into a specific format. Here are the options built into SQL Server:
DECLARE @convert_code INT = 100 -- See ...
