Tutorial by Examples: f

Find all elements with a certain attribute value

Imagine the following XML: <root> <element foobar="hello_world" /> <element example="this is one!" /> </root> The following XPath expression: /root/element[@foobar = 'hello_world'] will return the <element foobar="hello_world&quo...

xpath • Finding elements containing specific attributes

Neglect a few fields

Let's say you don't want the fields houseNum and street in the address field of the final populated doc, use the populate() as follows, Person.findOne({_id: req.params.id}) .populate('address', '-houseNum -street') // note the `-` symbol .exec(function(err, person) { // do somet...

mongoose • Mongoose Population

Populate only a few fields

If you only want the fields houseNum and street in the address field in the final populated doc, use the populate() function as follows in the above two methods, Person.findOne({_id: req.params.id}) .populate('address', 'houseNum street') .exec(function(err, person) { // do somet...

mongoose • Mongoose Population

Basic program for signup

Through this example, it will be explained to divide the node.js code into different modules/folders for better undertandibility. Following this technique makes it easier for other developers to understand the code as he can directly refer to concerned file instead of going through whole code. The m...

Node.js • Good coding style

Un-pivot a dynamic set of columns based on condition

The following example is a very useful basis when you are trying to convert transaction data to un-pivoted data for BI/reporting reasons, where the dimensions which are to be un-pivoted can have a dynamic set of columns. For our example, we suppose that the raw data table contains employee assessme...

MySQL • Dynamic Un-Pivot Table using Prepared Statement

Make device receive notification even when sleeping

When sending a notification to an iOS device, you must set priority: "high" for it to wake up. Otherwise, the notification will not be received while the phone is asleep. Sets the priority of the message. Valid values are "normal" and "high." On iOS, these correspond...

google-cloud-messaging • Differences between sending to Android and iOS devices

Accessing renderer from a native project

var renderer = Platform.GetRenderer(visualElement); if (renderer == null) { renderer = Platform.CreateRenderer(visualElement); Platform.SetRenderer(visualElement, renderer); } DoSomeThingWithRender(render); // now you can do whatever you want with render

Xamarin.Forms • Custom Renderers

C# implementation of OpenCL 1.2: number of platforms for an AMD system in 64-bit windows

OpenCL is low level api so it must be implemented in "C space" first. For that, one needs to download header files from Khronos' site. My hardware is AMD and capable of version 1.2, downloading opencl.h cl_platform.h cl.h cl_ext.h cl_egl.h cl_dx9_media_sharing.h cl_d3d10.h c...

opencl • Getting started with opencl

Basic mongodump of local default mongod instance

mongodump --db mydb --gzip --out "mydb.dump.$(date +%F_%R)" This command will dump a bson gzipped archive of your local mongod 'mydb' database to the 'mydb.dump.{timestamp}' directory

MongoDB • Backing up and Restoring Data

Basic mongorestore of local default mongod dump

mongorestore --db mydb mydb.dump.2016-08-27_12:44/mydb --drop --gzip This command will first drop your current 'mydb' database and then restore your gzipped bson dump from the 'mydb mydb.dump.2016-08-27_12:44/mydb' archive dump file.

MongoDB • Backing up and Restoring Data

Find My ancestors

XML <GrandFather name="Bardock" gender="male" spouse="Gine"> <Dad name="Goku" gender="male" spouse="Chi Chi"> <Me name="Gohan" gender="male"/> <brother name="Goten" ...