Tutorial by Examples: t

Update an existing model

$user = User::find(1); $user->name = 'abc'; $user->save(); You can also update multiple attributes at once using update, which does not require using save afterwards: $user = User::find(1); $user->update(['name' => 'abc', 'location' => 'xyz']); You can also update a model(s)...

Throw 404 if entity not found

If you want to automatically throw an exception when searching for a record that isn't found on a modal, you can use either Vehicle::findOrFail(1); or Vehicle::where('make', 'ford')->firstOrFail(); If a record with the primary key of 1 is not found, a ModelNotFoundException is thrown. W...

Reading and writing DataObjects

DataObjects in SilverStripe represent a database table row. The fields in the model have magic methods that handle getting and setting data via their property names. Given we have a simple DataObject as an example: class Fruit extends DataObject { private static $db = ['Name' => 'Varchar'...

A View Bound to Existing HTML

Assuming this HTML in the page: <body> <div id="myPage"> </div> </body> A view can be bound to it with: var MyPageView = Backbone.View.extend( { "el": "#myPage", "template": _.template( "<p>This is m...

View's initialize function

initialize is called by Backbone right after a View is constructed. Optional parameters The initialize function receives any arguments passed to the view's constructor. Commonly, the options hash that is used to pass the view's default options: ['model', 'collection', 'el', 'id', 'attributes', 'c...

Closing Streams

Most streams must be closed when you are done with them, otherwise you could introduce a memory leak or leave a file open. It is important that streams are closed even if an exception is thrown. Java SE 7 try(FileWriter fw = new FileWriter("outfilename"); BufferedWriter bw = new Buf...

Gem installation from github/filesystem

You can install a gem from github or filesystem. If the gem has been checked out from git or somehow already on the file system, you could install it using gem install --local path_to_gem/filename.gem Installing gem from github. Download the sources from github mkdir newgem cd newgem git clon...

Defining Variadic Functions

A Clojure function can be defined to take an arbitrary number of arguments, using the symbol & in its argument list. All remaining arguments are collected as a sequence. (defn sum [& args] (apply + args)) (defn sum-and-multiply [x & args] (* x (apply + args))) Calling: =&gt...

Single & Multiple line comments

Comments are programmer-readable annotations that are ignored at runtime. Their purpose is to make source code easier to understand. Single line comments The # character is used to add single line comments. #!/usr/bin/ruby -w # This is a single line comment. puts "Hello World!" Whe...

Tracing I2C Events

Note: I am assuming that debugfs is mounted under /sys/kernel/debug If not, try: mount -t debugfs none /sys/kernel/debug Change into the tracing directory: cd /sys/kernel/debug/tracing/ Make sure the function tracer is disabled: echo nop > current_tracer Enable all I2C events: echo ...

Use CStr to convert a numeric type to a string

Const zipCode As Long = 10012 Dim zipCodeText As String 'Convert the zipCode number to a string of digit characters zipCodeText = CStr(zipCode) 'zipCodeText = "10012"

Use Format to convert and format a numeric type as a string

Const zipCode As long = 10012 Dim zeroPaddedNumber As String zeroPaddedZipCode = Format(zipCode, "00000000") 'zeroPaddedNumber = "00010012"

Use StrConv to convert a byte-array of single-byte characters to a string

'Declare an array of bytes, assign single-byte character codes, and convert to a string Dim singleByteChars(4) As Byte singleByteChars(0) = 72 singleByteChars(1) = 101 singleByteChars(2) = 108 singleByteChars(3) = 108 singleByteChars(4) = 111 Dim stringFromSingleByteChars As String stringFro...

Implicitly convert a byte array of multi-byte-characters to a string

'Declare an array of bytes, assign multi-byte character codes, and convert to a string Dim multiByteChars(9) As Byte multiByteChars(0) = 87 multiByteChars(1) = 0 multiByteChars(2) = 111 multiByteChars(3) = 0 multiByteChars(4) = 114 multiByteChars(5) = 0 multiByteChars(6) = 108 multiByteChar...

Restart NGINX

As a root user: nginx -s restart Ubuntu example sudo service nginx restart

Reload NGINX configuration file

As a root user: sudo nginx -s reload Ubuntu 14.04 example sudo service nginx reload Ubuntu 16.04 example sudo systemctl reload nginx Before reloading, it is a good idea to check config for syntax errors: sudo nginx -t Or sudo service nginx configtest

Shutdown NGINX

Run as a root user. Fast shutdown: nginx -s stop Graceful shutdown: nginx -s quit

Return by Reference

Occasionally there comes time for you to implicitly return-by-reference. Returning by reference is useful when you want to use a function to find to which variable a reference should be bound. Do not use return-by-reference to increase performance. The engine will automatically optimize this o...

Using LocalBroadcastManager

LocalBroadcastManager is used to send Broadcast Intents within an application, without exposing them to unwanted listeners. Using LocalBroadcastManager is more efficient and safer than using context.sendBroadcast() directly, because you don't need to worry about any broadcasts faked by other Applic...

AES encryption of data using password in a secure way

The following example encrypts a given data block using AES. The encryption key is derived in a secure way (random salt, 1000 rounds of SHA-256). The encryption uses AES in CBC mode with random IV. Note that the data stored in the class EncryptedData (salt, iv, and encryptedData) can be concatenate...

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