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ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)
In this tutorial, you’ll discover how to perform HTTP GET and HTTP POST requests using the ESP32 board with Arduino IDE.
HTTP Request Methods:
HTTP, or Hypertext Transfer Protocol, acts as the communication method between a client and a server. Let’s break it down with an example:
The ESP32, acting as the client, sends an HTTP request to a Raspberry Pi running Node-RED, acting as the server. The server processes the request and sends back a response to the ESP32. The response typically includes status details about the request and may also include the requested content.
HTTP GET
HTTP GET is a method used to retrieve data from a specific resource. It’s commonly employed to fetch information from APIs.
GET /fetch-data?category=weather
In this example, the query string (with “category” representing the parameter and “weather” representing its value) is included in the URL of the HTTP GET request.
Alternatively, a simple request can be made to retrieve a value or JSON object, such as:
GET /get-info
(With HTTP GET, data is visible to everyone in the URL request.)
HTTP POST
HTTP POST is a method used to send data to a server for creating or updating a resource. For instance, you might use it to transmit sensor readings to a server.
The data being sent to the server with a POST request is stored in the request body of the HTTP request. Here’s an example:
POST /send-data HTTP/1.1
Host: example.com
api_key=123456&sensor_type=temperature&value=25.5
Content-Type: application/x-www-form-urlencoded
In the request body, you can also send a JSON object like this:
POST /send-data HTTP/1.1
Host: example.com
{"api_key": "123456", "sensor_type": "temperature", "value": 25.5}
Content-Type: application/json
Prerequisites
Before diving into this tutorial, ensure you’ve completed the following prerequisites:
1. Arduino IDE: Make sure you have the Arduino IDE installed on your computer.
2. ESP32 Board Add-On: You’ll be programming the ESP32 using Arduino IDE, so ensure you have the ESP32 add-on installed.
Follow the instructions to install the ESP32 board package in Arduino IDE for your operating system (Windows, Mac OS X, Linux).
3. Arduino_JSON Library: You’ll also need to install the Arduino_JSON library. This can be done through the Arduino IDE Library Manager.
Simply go to Sketch > Include Library > Manage Libraries, and search for “Arduino_JSON” in the Library Manager. Then, install the library.
