Hello world 👋🏻 my name is Francisco, fcoteroba on the Internet and today I’m bringing you another post where we’re going to do another project in our beloved 💚 programming language Python 🐍.
This project is somewhat more complex than the two previous ones already done on the web. If you haven’t seen them already, I recommend you see them before continuing with this one: How to make a calculator in the command console? as well as the project we did to generate QR codes.
Before we begin, although I’m going to explain what it is later, I recommend you visit a post I uploaded more than a month ago, where I explain many of the most used computer terms in our daily lives. Since, in this post, you’ll see words that probably won’t sound familiar to you. 🤯 You can read the post here.
I also want to remind you that a few weeks ago I uploaded a video to my YouTube channel, very interesting, focused on home automation. Specifically, we connected, configured, and installed a smart light bulb 💡 with which you can change its color, turn it off, turn it on, and much more simply by using your mobile phone and/or voice assistants like Google, Alexa, etc. 👇🏻
Now yes, let’s begin 👇🏻
What is an exchange?
Well, I imagine that before programming something, you’ll want to know what that thing is. For this, I’ll tell you what Wikipedia says about it:
Exchanges, also known as platforms or exchange markets, are digital platforms that allow exchanging digital currencies for fiat money and/or other cryptocurrencies or goods.
It’s a strange explanation at the same time as explicit, uniquely and exclusively focused on cryptocurrencies.
But, in reality, an exchange is defined as a site, web or (in our case) program to enter a value in a certain currency or cryptocurrency.
And that’s what we’re going to do today, we’re going to create a graphical interface, or GUI for its acronym in English in which, the user will insert a value in a certain currency and the program will show its current value in real time.
BEFORE YOU BEGIN YOU NEED TO KNOW THAT:
An API (word you’ll see in a moment) is (according to Red Hat’s website definition) a set of definitions and protocols that are used to develop and integrate application software. API means application programming interface.
In summary, an API is usually a file from an independent program, programmed uniquely and exclusively to be integrated into other applications.
Hey, how will we make it show the current value, if this is a market that varies every second?
I’m going to proceed to explain everything to you, step by step, just as we always do here. But first, I’m going to show you a small GIF of what you’re going to learn to program by reading this simple post! 😁
Now yes, here comes the first step 1️⃣.
We must register on ExchangeRate-API, which is a free, open and free API to perform conversions between the most varied currencies.
Registration is simple, we’ll just need to write the email address we want the free key to arrive at and press the button.
Once we register, a very long number will appear in our dashboard. That number is the API key that we’ll later use in Python 🐍.
When we have that code. Let’s start by opening our favorite IDE. Which in my case is VSCode and we’ll start importing the packages we’ll need in this project. 📦
Although I always say this when I make a post about Python, I remember that in this programming language it’s not necessary to specify what type the variable will be (Char, float, integer,…), unlike many other programming languages since, Python 🐍, will automatically understand the variable type according to what we store in it.
For this project we’re going to import tkinter in the following ways from tkinter import * and from tkinter import ttk. These two, will obviously be, to make the program’s graphical interface. Finally, we must also import the requests package, which works with web pages to decode their JSON, extract information and much more. The code is import requests.
WATCH OUT 👀, you’ll probably get an error with the requests package, and this is because you have to install it first in the command line using the pip installer. pip install requests
Reminder 🧠 Comments in Python are written by putting the symbol # at the beginning of the line Functions in programming. Functions, in summary, is a piece of code that, although written, will never be triggered until it’s invoked. 🧙🏻♂️
TKinter 🎨 We have to create a root window by setting a name before Tk(). Then we give the window size with minsize(valorx, valory). We set a title for the window with title(“Name”) And so that no user can enlarge or reduce the window size, we’ll set both parameters of resizable(x,y) to 0.
Adding all this, our program starts like this:
from tkinter import *
from tkinter import ttk
import requests
#Window definition
ventana = Tk()
ventana.minsize(500, 500)
ventana.title("Exchange made in Python | fcoterroba.com")
ventana.resizable(0,0)
Let’s now do the main part, everything that will appear in our main window.
1️⃣ First, we’re going to write a Label as a program title, giving it its respective design and layout configuration.
titulo_label = Label(ventana, text="¡Exchange de todas las monedas!")
titulo_label.config(
fg="white",
bg="black",
font=("Arial", 30),
padx=210,
pady=20
)
titulo_label.grid(row=0, column=0)
2️⃣ Second, set the text entry, even if it’s a number, Tkinter doesn’t distinguish it, so we’ll be the ones who give an alert if it’s not a number. The text entry will be stored in a variable that we must declare beforehand. I’ve done it right on the line below ventana.resizable
numero_label = Label(ventana, text="Dime el número y la moneda correspondiente")
numero_entry = Entry(ventana, textvariable=numero_data)
numero_label.grid(row=1, column=0, padx=5, pady=5)
numero_entry.grid(row=2, column=0, padx=5, pady=5)
3️⃣ The third part is creating the Comboboxes. These elements are like dropdown lists seen in web development or others. To create them in Python you must give it a name followed by ttk.Combobox(). Then, you have to block the user from being able to write on top of the list with ttk.Combobox(state=“readonly”) Finally, you must write all the values you want to appear in that Combobox. In this case, they’ll be all the currencies available in the API. This has to be repeated twice, first for your money currency and then the currency you want to convert it to.
combo = ttk.Combobox()
combo = ttk.Combobox(state="readonly")
combo["values"] = ["USD", 'AED', 'ARS', 'AUD', 'BGN', 'BRL', 'BSD', 'CAD', 'CHF', 'CLP', 'CNY', 'COP', 'CZK', 'DKK', 'DOP', 'EGP', 'EUR', 'FJD', 'GBP', 'GTQ', 'HKD', 'HRK', 'HUF', 'IDR', 'ILS', 'INR', 'ISK', 'JPY', 'KRW', 'KZT', 'MVR', 'MXN', 'MYR', 'NOK', 'NZD', 'PAB', 'PEN', 'PHP', 'PKR', 'PLN', 'PYG', 'RON', 'RUB', 'SAR', 'SEK', 'SGD', 'THB' 'TRY', 'TWD', 'UAH', 'UYU', 'ZAR']
combo.grid(row=3, column=0, padx=5, pady=5)
second_moneda = Label(ventana, text="A qué moneda lo quieres convertir?")
second_moneda.grid(row=4, column=0, padx=5, pady=5)
combo2 = ttk.Combobox()
combo2 = ttk.Combobox(state="readonly")
combo2["values"] = ["USD", 'AED', 'ARS', 'AUD', 'BGN', 'BRL', 'BSD', 'CAD', 'CHF', 'CLP', 'CNY', 'COP', 'CZK', 'DKK', 'DOP', 'EGP', 'EUR', 'FJD', 'GBP', 'GTQ', 'HKD', 'HRK', 'HUF', 'IDR', 'ILS', 'INR', 'ISK', 'JPY', 'KRW', 'KZT', 'MVR', 'MXN', 'MYR', 'NOK', 'NZD', 'PAB', 'PEN', 'PHP', 'PKR', 'PLN', 'PYG', 'RON', 'RUB', 'SAR', 'SEK', 'SGD', 'THB' 'TRY', 'TWD', 'UAH', 'UYU', 'ZAR']
combo2.grid(row=5, column=0, padx=5, pady=5)
4️⃣ We continue with the fourth step, which is to make the button with the command of a function that we’ll make in the next step. Function that will perform all the conversion logic and show the result. Also, let’s not forget ❗ our precious mainloop. So that the program appears visually.
boton = Button(ventana, text="Convertir", command=conversion)
boton.grid(row=6, column=0)
ventana.mainloop()
5️⃣ In our fifth step we’re going to create a function with the name we’ve given to the command property of our button. def conversion(): Inside that function, we’re going to do a try/except mainly for when the user inserts something other than numbers. TRY We’re going to create a variable to get the API URL adding the currency number 1 at the end with combo.get(). Then, we create a response variable to get the requests from the url with requests.get(url). After, we create another data variable to store the json from response.
And now yes, let’s start with the math! 🔣 We have to convert the number we have to float, creating a new variable. To finish we must create a new result variable multiplying that float number by the currency existing in the JSON file.
That said, we would only need to set a design and voilà.
EXCEPT We’re simply going to copy the design made for the previous result, putting a text about the error and making it somewhat more eye-catching.
def conversion():
try:
url = 'https://v6.exchangerate-api.com/v6/TU-API-KEY/latest/'+combo.get()
response = requests.get(url)
data = response.json()
numero1 = float(numero_entry.get())
resultado = round((numero1 * data['conversion_rates'][combo2.get()]), 2)
espacio = Label(ventana, text="")
espacio.grid(row=7, column=0)
resultado_label = Label(ventana, text=resultado)
resultado_label.grid(row=8, column=0)
resultado_label.config(
fg="black",
bg="white",
font=("Arial", 20),
padx=400,
pady=20
)
except:
espacio = Label(ventana, text="")
espacio.grid(row=7, column=0)
resultado_label = Label(ventana, text="Hay algo incorrecto. Recuerda que solo puedes escribir NÚMEROS")
resultado_label.grid(row=8, column=0)
resultado_label.config(
fg="red",
bg="black",
font=("Arial", 20),
padx=100,
pady=20
)
If we haven’t skipped any step, our project should look something like this:
And that’s been everything for today guys, I hope you liked this post as much as I enjoyed making it, programming the project and fighting with the API! After all, this is the beauty of programming, don’t you think? 🤓
We’ll see each other very soon here and you already know you can follow me on Twitter, Facebook, Instagram and LinkedIn. 🤟🏻