weatherstation/firmware/libraries/ESP8266_Influxdb/examples/QueryTable/QueryTable.ino

/**
 * QueryTable Example code for InfluxDBClient library for Arduino.
 * 
 * This example demonstrates querying recent history of values of WiFi signal level measured and stored in BasicWrite and SecureWrite examples.
 * 
 * Demonstrates connection to any InfluxDB instance accesible via:
 *  - unsecured http://...
 *  - secure https://... (appropriate certificate is required)
 *  - InfluxDB 2 Cloud at https://cloud2.influxdata.com/ (certificate is preconfigured)
 * 
 *  Enter WiFi and InfluxDB parameters below
 **/

#if defined(ESP32)
#include <WiFiMulti.h>
WiFiMulti wifiMulti;
#define DEVICE "ESP32"
#elif defined(ESP8266)
#include <ESP8266WiFiMulti.h>
ESP8266WiFiMulti wifiMulti;
#define DEVICE "ESP8266"
#endif

#include <InfluxDbClient.h>
#include <InfluxDbCloud.h>

// WiFi AP SSID
#define WIFI_SSID "SSID"
// WiFi password
#define WIFI_PASSWORD "PASSWORD"
// InfluxDB v2 server url, e.g. https://eu-central-1-1.aws.cloud2.influxdata.com (Use: InfluxDB UI -> Load Data -> Client Libraries)
// InfluxDB 1.8+  (v2 compatibility API) server url, e.g. http://192.168.1.48:8086
#define INFLUXDB_URL "server-url"
// InfluxDB v2 server or cloud API authentication token (Use: InfluxDB UI -> Load Data -> Tokens -> <select token>)
// InfluxDB 1.8+ (v2 compatibility API) use form user:password, eg. admin:adminpass
#define INFLUXDB_TOKEN "server token"
// InfluxDB v2 organization name or id (Use: InfluxDB UI -> Settings -> Profile -> <name under tile> )
// InfluxDB 1.8+ (v2 compatibility API) use any non empty string
#define INFLUXDB_ORG "org name/id"
// InfluxDB v2 bucket name (Use: InfluxDB UI -> Load Data -> Buckets)
// InfluxDB 1.8+ (v2 compatibility API) use database name
#define INFLUXDB_BUCKET "bucket name"

// Set timezone string according to https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
// Examples:
//  Pacific Time: "PST8PDT"
//  Eastern: "EST5EDT"
//  Japanesse: "JST-9"
//  Central Europe: "CET-1CEST,M3.5.0,M10.5.0/3"
#define TZ_INFO "CET-1CEST,M3.5.0,M10.5.0/3"

// InfluxDB client instance with preconfigured InfluxCloud certificate
InfluxDBClient client(INFLUXDB_URL, INFLUXDB_ORG, INFLUXDB_BUCKET, INFLUXDB_TOKEN, InfluxDbCloud2CACert);

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

  // Setup wifi
  WiFi.mode(WIFI_STA);
  wifiMulti.addAP(WIFI_SSID, WIFI_PASSWORD);

  Serial.print("Connecting to wifi");
  while (wifiMulti.run() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }
  Serial.println();

  // Accurate time is necessary for certificate validation
  // For the fastest time sync find NTP servers in your area: https://www.pool.ntp.org/zone/
  // Syncing progress and the time will be printed to Serial
  timeSync(TZ_INFO, "pool.ntp.org", "time.nis.gov");

  // Check server connection
  if (client.validateConnection()) {
    Serial.print("Connected to InfluxDB: ");
    Serial.println(client.getServerUrl());
  } else {
    Serial.print("InfluxDB connection failed: ");
    Serial.println(client.getLastErrorMessage());
  }
}

void loop() {
  // Construct a Flux query
  // Query will list RSSI for last 24 hours for each connected WiFi network of this device type
  String query = "from(bucket: \"" INFLUXDB_BUCKET "\") |> range(start: -24h) |> filter(fn: (r) => r._measurement == \"wifi_status\" and r._field == \"rssi\"";
  query += " and r.device == \""  DEVICE  "\")";

  Serial.println("==== List results ====");
  
  // Print composed query
  Serial.print("Querying with: ");
  Serial.println(query);

  // Send query to the server and get result
  FluxQueryResult result = client.query(query);

  // Iterate over rows. Even there is just one row, next() must be called at least once.
  while (result.next()) {
    // Check for new grouping key
    if(result.hasTableChanged()) {
      Serial.println("Table:");
      Serial.print("  ");
      // Print all columns name
      for(String &name: result.getColumnsName()) {
        Serial.print(name);
        Serial.print(",");
      }
      Serial.println();
      Serial.print("  ");
      // Print all columns datatype
      for(String &tp: result.getColumnsDatatype()) {
        Serial.print(tp);
        Serial.print(",");
      }
      Serial.println();
    }
    Serial.print("  ");
    // Print values of the row
    for(FluxValue &val: result.getValues()) {
      // Check whether the value is null
      if(!val.isNull()) {
        // Use raw string, unconverted value
        Serial.print(val.getRawValue());
      } else {
        // Print null value substite
        Serial.print("<null>");  
      }
      Serial.print(",");
    }
    Serial.println();
  }

  // Check if there was an error
  if(result.getError().length() > 0) {
    Serial.print("Query result error: ");
    Serial.println(result.getError());
  }

  // Close the result
  result.close();

  //Wait 10s
  Serial.println("Wait 10s");
  delay(10000);
}