URL Parameters

Demonstrates how to use Path Parameters (e.g. /users/{id}) and Query Parameters (e.g. ?page=2&limit=20) fluently.

Source: examples/UrlParameters/UrlParameters.ino

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Overview

Method	Syntax	Description
.path(key, value)	client.get("/users/{id}").path("id", 15)	Replaces placeholders in the route path with formatted values (/users/15).
.query(key, value)	client.get("/users").query("page", 2)	Appends query string parameters (/users?page=2).

Both methods support standard C/C++ data types: int, long, float, double, bool, const char*, and char*.

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Full Sketch

#include <Arduino.h>
#include <WiFi.h>
#include "ESP32HTTPClient.h"

const char* ssid     = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

ESP32HTTPClient client("https://jsonplaceholder.typicode.com");

void setup() {
    Serial.begin(115200);

    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("\nConnected to WiFi");
}

void loop() {
    // 1. Path Parameters: GET /users/{id} -> GET /users/15
    Serial.println("\n--- [1] Path Parameters Example ---");
    int userId = 15;
    char name[64] = {0};

    // Replaces {id} in the path with 15
    client.get("/users/{id}")
          .path("id", userId)
          .getBody("name", name, sizeof(name));

    if (client.isSuccess()) {
        Serial.printf("Path param resolved -> User: %s\n", name);
    }

    // 2. Query Parameters: GET /posts?userId=1&_limit=2
    Serial.println("\n--- [2] Query Parameters Example ---");
    char firstTitle[64] = {0};

    // Builds URL: /posts?userId=1&_limit=2
    client.get("/posts")
          .query("userId", 1)
          .query("_limit", 2)
          .getBody("0.title", firstTitle, sizeof(firstTitle));

    if (client.isSuccess()) {
        Serial.printf("Query params filtered -> First Post Title: %s\n", firstTitle);
    }

    // 3. Combining Path and Query Parameters
    Serial.println("\n--- [3] Path + Query Combined ---");
    // Builds URL: /users/1/posts?_limit=5&sort=desc
    client.get("/users/{userId}/posts")
          .path("userId", 1)
          .query("_limit", 5)
          .query("sort", "desc");

    if (client.isSuccess()) {
        Serial.println("Combined Path and Query executed successfully!");
    }

    delay(15000);
}

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Expected Serial Output

Connected to WiFi

--- [1] Path Parameters Example ---
Path param resolved -> User: Chelsey Dietrich

--- [2] Query Parameters Example ---
Query params filtered -> First Post Title: sunt aut facere repellat provident occaecati excepturi optio reprehenderit

--- [3] Path + Query Combined ---
Combined Path and Query executed successfully!

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Key Takeaways

• .path("key", val) replaces both {key} and key in the URL path.
• Multiple .query("key", val) calls automatically handle ? for the first parameter and & for subsequent parameters.
• No dynamic memory allocations or string formatting boilerplate needed (sprintf, String concatenation, etc.).