Introduction to Path and Query Parameters in C++

Welcome to another lesson of this course, leveraging C++ for interacting with RESTful APIs. In our previous lessons, we established a foundation by learning about RESTful APIs and executing GET requests using C++ libraries. Now, we will shift our focus to path and query parameters, essential tools for refining API requests and fetching specific data.

Path and query parameters are vital for making your API requests more precise and efficient. Imagine you are shopping online: selecting a specific item using its ID is similar to a path parameter, while filtering items by categories like price or color resembles query parameters. In this lesson, we'll explore these concepts with practical examples, empowering you to extract just the information you need from an API using C++.

Path parameters are part of the URL used to access specific resources within an API, acting like unique identifiers. For example, if you want to retrieve a to-do item with ID 3, the URL would be structured as follows:

http://localhost:8000/todos/3

In this case, 3 is the path parameter specifying the particular item you wish to access.

Query parameters are added to the URL after a ? to filter or modify the data returned by the API. They are formatted as key-value pairs. For instance, if you want to list only the completed to-do tasks, your request would be:

http://localhost:8000/todos?done=true

Here, done=true is the query parameter filtering the results to include only tasks that are marked as completed.

Before jumping into implementing these parameters using C++, let's ensure everything is set up correctly. We will use the httplib library to handle HTTP requests and the nlohmann::json library to manage JSON responses. Here’s how to set up the HTTP client:

#include "httplib.h"
#include <iostream>
#include <nlohmann/json.hpp>

// Base URL for the API
const std::string base_url = "http://localhost:8000";

int main() {
    httplib::Client cli("localhost", 8000);
    // Your code examples will go here
    return 0;
}