Merge pull request #173 from tobiasschuerg/feat/query_params

feat: Adding query params

Author: vlastahajek

CHANGELOG.md

@@ -3,8 +3,9 @@
 ### Features
  - [167](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/167) - Added `InfluxDBClient::writeRecord(const char *record)`.
  - [167](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/167) - Added possibility to disable retrying by setting `maxRetryAttempts` to zero: `client.setWriteOptions(WriteOptions().maxRetryAttempts(0));` 
- - [172](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/170) - Added directly streaming batch for write. It can be enable by `InfluxDBClient::setStreamWrite(bool enable = true)`. Writing by streaming lines of batch saves RAM as it sends data without allocating a buffer. On the other hand, this way of writing is about half times slower than the classic way, when allocating the buffer for writing the whole batch. 
-  - [172](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/170) - Allowing larger batch size, > 255.
+ - [172](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/172) - Added directly streaming batch for write. It can be enable by `InfluxDBClient::setStreamWrite(bool enable = true)`. Writing by streaming lines of batch saves RAM as it sends data without allocating a buffer. On the other hand, this way of writing is about half times slower than the classic way, when allocating the buffer for writing the whole batch. 
+  - [172](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/172) - Allowing larger batch size, > 255.
+  - [173](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/173) - Added Flux query parameters. Now supported by InfluxDB Cloud only.
 
 ## 3.9.0 [2021-09-17]
 ### Features

README.md

@@ -33,6 +33,7 @@ This library doesn't support using those devices as a peripheral.
     - [InfluxDb 1](#influxdb-1)
     - [Skipping certificate validation](#skipping-certificate-validation)
   - [Querying](#querying)
+    - [Parametrized Queries](#parametrized-queries)
   - [Original API](#original-api)
     - [Initialization](#initialization)
     - [Sending a single measurement](#sending-a-single-measurement)
@@ -524,6 +525,87 @@ if(result.getError() != "") {
 ```
 Complete source code is available in [QueryAggregated example](examples/QueryAggregated/QueryAggregated.ino).
 
+### Parametrized Queries
+InfluxDB Cloud supports [Parameterized Queries](https://docs.influxdata.com/influxdb/cloud/query-data/parameterized-queries/)
+that let you dynamically change values in a query using the InfluxDB API. Parameterized queries make Flux queries more
+reusable and can also be used to help prevent injection attacks.
+
+InfluxDB Cloud inserts the params object into the Flux query as a Flux record named `params`. Use dot or bracket
+notation to access parameters in the `params` record in your Flux query. Parameterized Flux queries support only `int`
+, `float`, and `string` data types. To convert the supported data types into
+other [Flux basic data types, use Flux type conversion functions](https://docs.influxdata.com/influxdb/cloud/query-data/parameterized-queries/#supported-parameter-data-types).
+
+Parameterized query example:
+> :warning: Parameterized Queries are supported only in InfluxDB Cloud, currently there is no support in InfluxDB OSS.
+
+```cpp
+// Prepare query parameters
+QueryParams params;
+params.add("bucket", INFLUXDB_BUCKET);
+params.add("since", "-5m");
+params.add("device", DEVICE);
+params.add("rssiThreshold", -50);
+
+// Construct a Flux query using parameters
+// Parameters are accessed via the 'params' Flux object
+// Flux only supports only string, float and int as parameters. Duration can be converted from string.
+// Query will find RSSI less than defined threshold
+String query = "from(bucket: params.bucket) |> range(start: duration(v: params.since)) \
+  |> filter(fn: (r) => r._measurement == \"wifi_status\") \
+  |> filter(fn: (r) => r._field == \"rssi\") \
+  |> filter(fn: (r) => r.device == params.device) \
+  |> filter(fn: (r) => r._value < params.rssiThreshold)";
+
+// Print ouput header
+// Print composed query
+Serial.print("Querying with: ");
+Serial.println(query);
+
+// Send query to the server and get result
+FluxQueryResult result = client.query(query, params);
+
+//Print header
+Serial.printf("%10s %20s %5s\n","Time","SSID","RSSI");
+
+for(int i=0;i<37;i++) {
+  Serial.print('-');
+}
+Serial.println();
+
+// Iterate over rows. Even there is just one row, next() must be called at least once.
+int c = 0;
+while (result.next()) {
+  // Get converted value for flux result column 'SSID'
+  String ssid = result.getValueByName("SSID").getString();
+  
+  // Get converted value for flux result column '_value' where there is RSSI value
+  long rssi = result.getValueByName("_value").getLong();
+
+  // Get converted value for the _time column
+  FluxDateTime time = result.getValueByName("_time").getDateTime();
+
+  // Format date-time for printing
+  // Format string according to http://www.cplusplus.com/reference/ctime/strftime/
+  String timeStr = time.format("%F %T");
+  // Print formatted row
+  Serial.printf("%20s %10s %5d\n", timeStr.c_str(), ssid.c_str() ,rssi);
+  c++;
+}
+if(!c) {
+  Serial.println(" No data found");
+}
+
+// Check if there was an error
+if(result.getError() != "") {
+  Serial.print("Query result error: ");
+  Serial.println(result.getError());
+}
+
+// Close the result
+result.close();
+```
+Complete source code is available in [QueryParams example](examples/QueryParams/QueryParams.ino).
+
 ## Original API
 
 ### Initialization

examples/QueryParams/QueryParams.ino

@@ -0,0 +1,154 @@
+/**
+ * QueryParams Example code for InfluxDBClient library for Arduino.
+  * 
+ * This example demonstrates querying using parameters inserted into the Flux query. We select WiFi signal level values bellow a certain threshold. 
+ * WiFi signal is measured and stored in BasicWrite and SecureWrite examples.
+ * 
+ * Demonstrates connection to any InfluxDB instance accesible via:
+ *  - 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());
+  }
+}
+
+
+// Queries WiFi signal level values bellow a certain threshold using parameters inserted into the Flux query
+// Prints composed query and the result values.
+void loop() {
+  // Prepare query parameters
+  QueryParams params;
+  params.add("bucket", INFLUXDB_BUCKET);
+  params.add("since", "-5m");
+  params.add("device", DEVICE);
+  params.add("rssiTreshold", -50);
+  
+  // Construct a Flux query using parameters
+  // Parameters are accessed via the 'params' Flux object
+  // Flux only supports only string, float and int as parameters. Duration can be converted from string.
+  // Query will find RSSI less than defined treshold
+  String query = "from(bucket: params.bucket) |> range(start: duration(v: params.since)) \
+    |> filter(fn: (r) => r._measurement == \"wifi_status\") \
+    |> filter(fn: (r) => r._field == \"rssi\") \
+    |> filter(fn: (r) => r.device == params.device) \
+    |> filter(fn: (r) => r._value < params.rssiTreshold)";
+
+  // Print ouput header
+  // Print composed query
+  Serial.print("Querying with: ");
+  Serial.println(query);
+
+  // Send query to the server and get result
+  FluxQueryResult result = client.query(query, params);
+
+  //Print header
+  Serial.printf("%10s %20s %5s\n","Time","SSID","RSSI");
+
+  for(int i=0;i<37;i++) {
+    Serial.print('-');
+  }
+  Serial.println();
+
+  // Iterate over rows. Even there is just one row, next() must be called at least once.
+  int c = 0;
+  while (result.next()) {
+    // Get converted value for flux result column 'SSID'
+    String ssid = result.getValueByName("SSID").getString();
+   
+    // Get converted value for flux result column '_value' where there is RSSI value
+    long rssi = result.getValueByName("_value").getLong();
+
+    // Get converted value for the _time column
+    FluxDateTime time = result.getValueByName("_time").getDateTime();
+
+    // Format date-time for printing
+    // Format string according to http://www.cplusplus.com/reference/ctime/strftime/
+    String timeStr = time.format("%F %T");
+    // Print formatted row
+    Serial.printf("%20s %10s %5d\n", timeStr.c_str(), ssid.c_str() ,rssi);
+    c++;
+  }
+  if(!c) {
+    Serial.println(" No data found");
+  }
+
+  // Check if there was an error
+  if(result.getError() != "") {
+    Serial.print("Query result error: ");
+    Serial.println(result.getError());
+  }
+
+  // Close the result
+  result.close();
+  // Wait 15s
+  delay(15000);
+}

src/InfluxDbClient.cpp

@@ -572,9 +572,16 @@ static const char QueryDialect[] PROGMEM = "\
 \"header\": true,\
 \"delimiter\": \",\",\
 \"commentPrefix\": \"#\"\
-}}";
+}";
+
+static const char Params[] PROGMEM = ",\
+\"params\": {";
 
 FluxQueryResult InfluxDBClient::query(String fluxQuery) {
+    return query(fluxQuery, QueryParams());
+}
+
+FluxQueryResult InfluxDBClient::query(String fluxQuery, QueryParams params) {
     uint32_t rwt = getRemainingRetryTime();
     if(rwt > 0) {
         INFLUXDB_CLIENT_DEBUG("[W] Cannot query yet, pause %ds, %ds yet\n", _retryTime, rwt);
@@ -590,12 +597,28 @@ FluxQueryResult InfluxDBClient::query(String fluxQuery) {
     INFLUXDB_CLIENT_DEBUG("[D] Query to %s\n", _queryUrl.c_str());
     INFLUXDB_CLIENT_DEBUG("[D] JSON query:\n%s\n", fluxQuery.c_str());
 
-    String body = F("{\"type\":\"flux\",\"query\":\"");
-    body += escapeJSONString(fluxQuery) + "\",";
+    String queryEsc = escapeJSONString(fluxQuery);
+    String body;
+    body.reserve(150 + queryEsc.length() + params.size()*30);
+    body = F("{\"type\":\"flux\",\"query\":\"");
+    body +=  queryEsc;
+    body += "\",";
     body += FPSTR(QueryDialect);
-
+    if(params.size()) {
+        body += FPSTR(Params);
+        body += params.jsonString(0);
+        for(int i=1;i<params.size();i++) {
+            body +=",";
+            char *js = params.jsonString(i);
+            body += js;
+            delete [] js;
+        }
+        body += '}';
+    }
+    body += '}';
     CsvReader *reader = nullptr;
     _retryTime = 0;
+    INFLUXDB_CLIENT_DEBUG("[D] Query: %s\n", body.c_str());
     if(_service->doPOST(_queryUrl.c_str(), body.c_str(), PSTR("application/json"), 200, [&](HTTPClient *httpClient){
         bool chunked = false;
         if(httpClient->hasHeader(TransferEncoding)) {

src/InfluxDbClient.h

@@ -32,6 +32,7 @@
 #include "Point.h"  
 #include "WritePrecision.h"
 #include "query/FluxParser.h"
+#include "query/Params.h"
 #include "util/helpers.h"
 #include "Options.h"
 #include "BucketsClient.h"
@@ -130,6 +131,10 @@ class InfluxDBClient {
     // Use FluxQueryResult::next() method to iterate over lines of the query result.
     // Always call of FluxQueryResult::close() when reading is finished. Check FluxQueryResult doc for more info.
     FluxQueryResult query(String fluxQuery);
+    // Sends Flux query with params and returns FluxQueryResult object for subsequently reading flux query response.
+    // Use FluxQueryResult::next() method to iterate over lines of the query result.
+    // Always call of FluxQueryResult::close() when reading is finished. Check FluxQueryResult doc for more info.
+    FluxQueryResult query(String fluxQuery, QueryParams params);
     // Forces writing of all points in buffer, even the batch is not full.
     // Returns true if successful, false in case of any error 
     bool flushBuffer();

src/query/FluxParser.cpp

@@ -202,7 +202,7 @@ bool FluxQueryResult::next() {
 	return true;
 }
 
-FluxDateTime *FluxQueryResult::convertRfc3339(String value, const char *type) {
+FluxDateTime *FluxQueryResult::convertRfc3339(String &value, const char *type) {
     tm t = {0,0,0,0,0,0,0,0,0};
     // has the time part
     int zet = value.indexOf('Z');
@@ -240,7 +240,7 @@ FluxDateTime *FluxQueryResult::convertRfc3339(String value, const char *type) {
     return new FluxDateTime(value, type, t, fracts);
 }
 
-FluxBase *FluxQueryResult::convertValue(String value, String dataType) {
+FluxBase *FluxQueryResult::convertValue(String &value, String &dataType) {
     FluxBase *ret = nullptr;
     if(dataType.equals(FluxDatatypeDatetimeRFC3339) || dataType.equals(FluxDatatypeDatetimeRFC3339Nano)) {
         const char *type = FluxDatatypeDatetimeRFC3339;

src/query/FluxParser.h

@@ -86,8 +86,8 @@ class FluxQueryResult {
     // Descructor
     ~FluxQueryResult();
 protected:
-    FluxBase *convertValue(String value, String dataType);
-    static FluxDateTime *convertRfc3339(String value, const char *type);
+    FluxBase *convertValue(String &value, String &dataType);
+    static FluxDateTime *convertRfc3339(String &value, const char *type);
     void clearValues();
     void clearColumns();
 private: