Added Thingspeak client to fetch data from a channel

Author: squix78

ThingspeakClient.cpp

@@ -0,0 +1,123 @@
+#include "ThingspeakClient.h"
+
+
+ThingspeakClient::ThingspeakClient() {
+  
+}
+    
+void ThingspeakClient::getLastChannelItem(String channelId, String readApiKey) {
+  JsonStreamingParser parser;
+  parser.setListener(this);
+  WiFiClient client;
+
+  // http://api.thingspeak.com/channels/CHANNEL_ID/feeds.json?results=2&api_key=API_KEY
+  const char host[] = "api.thingspeak.com";
+  String url = "/channels/" + channelId +"/feeds.json?results=1&api_key=" + readApiKey;
+  
+  const int httpPort = 80;
+  if (!client.connect(host, httpPort)) {
+    Serial.println("connection failed");
+    return;
+  }
+
+  
+  Serial.print("Requesting URL: ");
+  Serial.println(url);
+  
+  // This will send the request to the server
+  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
+               "Host: " + host + "\r\n" + 
+               "Connection: close\r\n\r\n");
+  while(!client.available()) {
+    Serial.println(".");
+    delay(1000); 
+  }
+  
+  int pos = 0;
+  boolean isBody = false;
+  char c;
+
+  int size = 0;
+  client.setNoDelay(false);
+  while(client.connected()) {
+    while((size = client.available()) > 0) {
+      c = client.read();
+      if (c == '{' || c == '[') {
+        isBody = true;
+      }
+      if (isBody) {
+        parser.parse(c);
+      }
+    }
+  }  
+}
+
+void ThingspeakClient::whitespace(char c) {
+  
+}
+
+void ThingspeakClient::startDocument() {
+  
+}
+
+void ThingspeakClient::key(String key) {
+  if (key == "channel") {
+    isHeader = true;
+  } else if (key == "feeds") {
+    isHeader = false;
+  } 
+  currentKey = key;
+}
+
+void ThingspeakClient::value(String value) {
+    //Serial.println(currentKey +": " + value);
+
+      for (int i = 1; i < 9; i++) {
+        String fieldKey = "field" + String(i);
+  
+        if (currentKey == fieldKey) {
+          if (isHeader) {
+            fieldLabels[i-1] = value;
+          } else {
+            lastFields[i-1] = value;
+            Serial.println(fieldKey + ": " + value);
+          }
+          
+        }
+      }
+    
+  
+}
+
+
+String ThingspeakClient::getFieldLabel(int index) {
+  return fieldLabels[index];
+}
+
+String ThingspeakClient::getFieldValue(int index) {
+  return lastFields[index];
+}
+
+String ThingspeakClient::getCreatedAt() {
+  return createdAt;
+}
+
+void ThingspeakClient::endArray() {
+  
+}
+
+void ThingspeakClient::endObject() {
+  
+}
+
+void ThingspeakClient::endDocument() {
+  
+}
+
+void ThingspeakClient::startArray() {
+  
+}
+
+void ThingspeakClient::startObject() {
+  
+}

ThingspeakClient.h

@@ -0,0 +1,72 @@
+/**The MIT License (MIT)
+
+Copyright (c) 2015 by Daniel Eichhorn
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+See more at http://blog.squix.ch
+*/
+
+#pragma once
+
+#include <JsonListener.h>
+#include <JsonStreamingParser.h>
+#include <ESP8266WiFi.h>
+#include <WiFiClient.h>
+
+#define MAX_FORECAST_PERIODS 7
+
+class ThingspeakClient: public JsonListener {
+  private:
+    // Thingspeak has a maximum of 8 fields
+    String lastFields[8];
+    String fieldLabels[8];
+    String createdAt;
+    boolean isHeader = true;
+    String currentKey = "";
+    
+  public:
+    ThingspeakClient();
+    
+    void getLastChannelItem(String channelId, String readApiKey);
+
+    String getFieldLabel(int index);
+
+    String getFieldValue(int index);
+
+    String getCreatedAt();
+    
+    virtual void whitespace(char c);
+  
+    virtual void startDocument();
+
+    virtual void key(String key);
+
+    virtual void value(String value);
+
+    virtual void endArray();
+
+    virtual void endObject();
+
+    virtual void endDocument();
+
+    virtual void startArray();
+
+    virtual void startObject();
+};