An F() object represents the value of a model field or annotated column. It makes it possible to refer to model field values and perform database operations using them without actually having to pull them out of the database into Python memory. - F() expressions
It is appropriate to use F() obj...
Supposing you have setup a django project, and the settings file is in an app named main, this is how you initialize your code
import os, sys
# Setup environ
sys.path.append(os.getcwd())
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "main.settings")
# Setup django
imp...
Magento has a powerful set of methods to filter collections. Since there are two types of Objects that can be contained in collections, we must first determine which type of data we are working with before we can filter it. Magento implements a EAV data model for entities such as products and catego...
When we query our data, we often need more than one filter to get the exact data set we are looking for. In SQL, we handle this with AND and OR clauses. We can achieve the same thing with collections.
To add an AND clause to your query, just simply add another method call. This will append the seco...
This uses the SwiftyDropbox library to upload a file from a NSFileHandle to the Dropbox account using upload sessions, handling every error case:
import UIKit
import SwiftyDropbox
class ViewController: UIViewController {
// filled in later in doUpload:
var fileHandle : NSFileHandle?...
var express = require("express"),
bodyParser = require("body-parser"),
server = express();
//body parser for parsing request body
server.use(bodyParser.json());
server.use(bodyParser.urlencoded({ extended: true }));
//temperary store for `item` in memory
var it...
Use the double negation syntax to check for truthiness of values. All values correspond to a boolean, irrespective of their type.
irb(main):001:0> !!1234
=> true
irb(main):002:0> !!"Hello, world!"
(irb):2: warning: string literal in condition
=> true
irb(main):003:0> !...
JSON (JavaScript Object Notation) is a lightweight data interchange format.
Many web applications use it to send and receive data.
In Ruby you can simply work with JSON.
At first you have to require 'json', then you can parse a JSON string via the JSON.parse() command.
require 'json'
j = '{&q...
Returns a partially applied function.
> ((curry + 10) 20)
30
curryr can be used when the arguments need to be inserted at the end. In other words, (curryr list 1 2) will produce a function expecting some new-arguments .... When called, that new function will in turn call (list new-arguments ...
Your app can't access your reminders and your calendar without permission. Instead, it must show an alert to user, requesting him/her to grant access to events for the app.
To get started, import the EventKit framework:
Swift
import EventKit
Objective-C
#import <EventKit/EventKit.h>
...
Accessing the array of calendars
To access the array of EKCalendars, we use the calendarsForEntityType method:
Swift
let calendarsArray = eventStore.calendarsForEntityType(EKEntityType.Event) as! [EKCalendar]
Iterating through calendars
Just use a simple for loop:
Swift
for calendar in cale...
This is an example to show how to change the allowed choices on a subCategory select field depending on the value of the category select field.
To do that you have to make your subCategory choices dynamical for both client and server side.
1. Make the form dynamic on the client side for display / ...
In Ruby, there is always an implicit receiver for all method calls. The language keeps a reference to the current implicit receiver stored in the variable self. Certain language keywords like class and module will change what self points to. Understanding these behaviors is very helpful in mastering...
When you define a class or module, the implicit receiver becomes a reference to the class itself. For example:
puts "I am #{self}"
class Example
puts "I am #{self}"
end
Executing the above code will print:
"I am main"
"I am Example"
BEGIN TRY -- start error handling
BEGIN TRANSACTION; -- from here on transactions (modifictions) are not final
-- start your statement(s)
select 42/0 as ANSWER -- simple SQL Query with an error
-- end your statement(s)
COMMIT TRANSACTION; -- finalize all transa...
Sometimes we have another editor somewhere else instead of TinyMCE (Wordpress Default Editor). That happen when we are creating our own Theme, Plugin or something specific; and we need to write and manipulate a type of post and save it into our WP Database.
So, if you are on that situation, you can...
