JSON Objects Explained

 

JSON Objects: Structured Data Explained

JSON, or JavaScript Object Notation, is a widely used format for representing structured data. It's concise, human-readable, and easily understood by both humans and machines, making it a popular choice for web applications, APIs, and data exchange. Let's dive into the essence of JSON objects:

Imagine a box: This box represents a JSON object. Inside the box, you can store items, but not just any items – only key-value pairs. Just like labels and their corresponding contents, each key uniquely identifies a piece of data (the value).

Structure Matters:

• Keys: They act as unique identifiers, written in double quotes and always strings. Imagine them as labels on your box compartments.
• Values: These can be various data types: strings, numbers, booleans (true/false), null, or even arrays and other objects (nesting allowed!). They represent the actual information stored within each compartment.
• Commas & Braces: Commas separate key-value pairs, and curly braces ({ and }) enclose the entire object, defining its boundaries.

Bringing it Together:

Here's a simple example:

JSON

{ "name": "Alice", "age": 30, "isStudent": true, "hobbies": ["reading", "hiking", "coding"] }

Key Points to Remember:

• Order doesn't matter: Unlike some data structures, the order of key-value pairs within a JSON object doesn't affect its meaning.
• No duplicate keys: Each key within an object must be unique. You can't have two keys with the same name.
• Nesting allowed: Objects can contain other objects or arrays, creating complex data structures.

Applications of JSON Objects:

JSON objects are incredibly versatile and find use in various contexts:

• Web APIs: They seamlessly transfer data between servers and clients in web applications.
• Configuration files: They store settings and options for various applications.
• Data storage: They provide a lightweight and flexible way to store structured data.
• Data exchange: They facilitate data exchange between different systems and platforms.

Raspberry Pico W TM1637 display and JSON object

Raspberry Pico W project shows Bitcoin value on TM1637 display from JSON object.  

TM1637 LED 7-segment display you need the tm1627 library. Download it from Thonny plug-ins.

Code in MicroPython Thonny IDE

Data from a JSON object stored in the response variable. The json() method of the response object is used to parse the JSON data and convert it into a MicroPython dictionary.

JSON object:

The value of the "USD" rate is then being accessed using the following line of code: data["bpi"]["USD"]["rate_float"]. This line accesses the "bpi" key of the dictionary, then accesses the "USD" key within that dictionary, and finally accesses the "rate_float" key within the "USD" dictionary. The resulting value is stored in the price variable.

Create a new script by clicking the new button on Thonny IDE. Copy and paste the following code.

CODE secrets.py

SSD="SSID" PASS="PASSWORD"

Replace SSID and PASSWORD with your own Wi-Fi credentials.

CODE main.py

import network

import utime

from machine import I2C, Pin

import tm1637 

import secrets

import time

import urequests

led = machine.Pin("LED", machine.Pin.OUT)

wlan = network.WLAN(network.STA_IF)

wlan.active(True)

wlan.connect(secrets.SSD, secrets.PASS)

print(wlan.isconnected())

# Get the current Bitcoin price

def get_price():

    url = "https://api.coindesk.com/v1/bpi/currentprice/BTC.json"

    response = urequests.get(url)

    data = response.json()

    price = data["bpi"]["USD"]["rate_float"]

    return price

def round_to_even(n):

    if n % 2 == 0.5:

        return round(n) + 1 if round(n) % 2 == 1 else round(n)

    return round(n)

display = tm1637.TM1637(clk=Pin(0), dio=Pin(1)) # put the right pins

while True:

    price = get_price()

    result = round_to_even(price)

    if price is None:

        for i in range(3):

            led.value(not led.value())

            utime.sleep(0.5)

    else:

       led.value(1)

       print(result) # print result in Shell

       display.scroll(str(result))

       time.sleep(20)

Raspberry Pico W Pinouts and TM1637