Tutorial by Examples: o

func CORS(h http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { origin := r.Header.Get("Origin") w.Header().Set("Access-Control-Allow-Origin", origin) if r.Method == "OPTIONS" { ...

func Recovery(h http.Handler) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){ defer func() { if err := recover(); err != nil { // respondInternalServerError } }() h.ServeHTTP(w , r) }...

Usually output of a command goes to the terminal. Using the concept of Output redirection, the output of a command can be redirected to a file. So insted of displaying the output to the terminal it can be send to a file. '>' character is used for output redirection. $ pwd > file1 $ cat file...

The commands normally take their input from the standard input device keyboard. Using Input redirection concept, we can have their input redirected from a file. To redirect standard input from a file instead of the keyboard, the '<' character is used. $ cat file1 monday tuesday wednsday th...

The example assumes you have successfully run and fully understand the tutorial of MNIST(Deep MNIST for expert). %matplotlib inline import matplotlib.pyplot as plt # con_val is a 4-d array, the first indicates the index of image, the last indicates the index of kernel def display(con_val, kern...

Install Apache Web Server First step is to install web server Apache. sudo yum -y install httpd Once it is installed, enable (to run on startup) and start Apache web server service. sudo systemctl enable --now httpd Point your browser to: http://localhost You will see the default Apache web s...

Step 1 : Install the node-inspector package using npm globally on you machine $ npm install -g node-inspector Step 2 : Start the node-inspector server $ node-inspector Step 3 : Start debugging your node application $ node --debug-brk your/short/node/script.js Step 4 : Open http://127.0....

Is raised when you tried to use a variable, method or function that is not initialized (at least not before). In other words, it is raised when a requested local or global name is not found. It's possible that you misspelt the name of the object or forgot to import something. Also maybe it's in anot...

AssertError The assert statement exists in almost every programming language. When you do: assert condition or: assert condition, message It's equivalent to this: if __debug__: if not condition: raise AssertionError(message) Assertions can include an optional message, and you can d...

json_util provides two helper methods, dumps and loads, that wrap the native json methods and provide explicit BSON conversion to and from json. Simple usage from bson.json_util import loads, dumps record = db.movies.find_one() json_str = dumps(record) record2 = loads(json_str) if record is:...

python-bsonjs does not depend on PyMongo and can offer a nice performance improvement over json_util: bsonjs is roughly 10-15x faster than PyMongo’s json_util at decoding BSON to JSON and encoding JSON to BSON. Note that: to use bsonjs effectively, it is recommended to work directly with Ra...

If all you need is serializing mongo results into json, it is possible to use the json module, provided you define custom handlers to deal with non-serializable fields types. One advantage is that you have full power on how you encode specific fields, like the datetime representation. Here is a ha...

Import a Mongoose Model (See topic "Mongoose Schemas") var User = require("../models/user-schema.js") The findOne method will return the first entry in the database that matches the first parameter. The parameter should be an object where the key is the field to look for and th...

new Vue({ el:"#app", data:{ foo: "bar" }, methods:{ doSomethingAsynchronous(){ setTimeout(function(){ // This is wrong! Inside this function, // "this" refers to the window object. this.foo = "baz"; ...

new Vue({ el:"#star-wars-people", data:{ people: null }, mounted: function(){ $.getJSON("http://swapi.co/api/people/", function(data){ // Again, this is wrong! "this", here, refers to the window. this.people = data.results; }) ...

You can capture the correct this using a closure. new Vue({ el:"#star-wars-people", data:{ people: null }, mounted: function(){ // Before executing the web service call, save this to a local variable var self = this; $.getJSON("http://swapi.co/api/peop...

new Vue({ el:"#star-wars-people", data:{ people: null }, mounted: function(){ $.getJSON("http://swapi.co/api/people/", data => this.people = data.results); } }) Caution! Arrow functions are a syntax introduced in Ecmascript 2015. It is not yet supp...

new Vue({ el:"#app", data:{ foo: "bar" }, methods:{ // This is wrong! Arrow functions capture "this" lexically // and "this" will refer to the window. doSomething: () => this.foo = "baz" } })

new Vue({ el:"#app", data:{ foo: "bar" }, methods:{ doSomething: function(){ this.foo = "baz" } } }) Alternatively, if you are using a javascript compiler or a browser that supports Ecmascript 2015 new Vue({ el:"#app&quo...

Using the move command, you can move files: @echo off cd C:\Foo\Bat\Baz move /Y Meow.bat "Meow Folder" >nul Meow.bat stands for which file to move. The "Meow Folder" moves Meow.bat to the Meow Folder. /Y says to not prompt for confirmation. Replacing that with /-Y makes ...