GraphQL Queries and Mutations

ESP32-HTTP-Client provides a dedicated, fluent API for GraphQL operations with direct stream-to-variable binding and zero-heap overhead.

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Basic Query (POST)

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

ESP32HTTPClient client("https://api.example.com");

String name;
int id;

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

  client.graphql("/graphql")
      .query("query { user { id name } }")
      .getData("user.id", &id)
      .getData("user.name", &name);

  if (client.isSuccess()) {
    Serial.printf("User: %s (ID: %d)\n", name.c_str(), id);
  }
}

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Query via HTTP GET

According to the GraphQL over HTTP specification, read-only queries can be executed via HTTP GET:

String status;

client.graphqlGet("/graphql")
    .query("{ systemHealth }")
    .getData("systemHealth", &status);

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GraphQL Mutations (POST)

Mutations modify server-side data and are executed via HTTP POST:

int deviceId = 0;
String status;

client.graphql("/graphql")
    .mutation("mutation Register { registerNode(type: \"ESP32\") { id status } }")
    .getData("registerNode.id", &deviceId)
    .getData("registerNode.status", &status);