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Destroyed Examples (markdown)
Benoît Blanchon
162
Examples.md
162
Examples.md
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This page contains user contributed examples, feel free to edit.
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For official examples, go to: https://arduinojson.org/example/
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## Example 1: complex nested object
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From [issue #85](https://github.com/bblanchon/ArduinoJson/issues/85):
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```json
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[
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{
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"error": {
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"address": "",
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"description": "link button not pressed",
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"type": "101"
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}
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}
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]
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```
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Can be generated with the following code:
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```c++
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DynamicJsonBuffer jsonBuffer;
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JsonArray& root = jsonBuffer.createArray();
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JsonObject& error = root.createNestedObject().createNestedObject("error");
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error["address"] = "";
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error["description"] = "link button not pressed";
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error["type"] = "101";
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root.prettyPrintTo(Serial);
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```
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And, while stored in `char json[]` can be decoded with the following code:
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```c++
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DynamicJsonBuffer jsonBuffer;
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JsonArray& root = jsonBuffer.parseArray(json);
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JsonObject& error = root[0]["error"];
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const char* address = error["address"];
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const char* description = error["description"];
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int type = error["type"];
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```
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Don't forget to replace the `DynamicJsonBuffer` by a `StaticJsonBuffer` if you need to run on an embedded platform like an Arduino.
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## Example 2: get the weather data from aviationweather.gov or geonames.org
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char *MTserverName = "api.geonames.org"; // server name
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String cmd = "GET /weatherIcaoJSON?ICAO="; // prepare the command to send to the web server after
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getting the data on JSON format and parsing the buffer:
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JsonObject& _root = jsonBuffer.parseObject(MTjson); // parse the JSON buffer
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if (!_root.success()) { // everything OK
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Serial.println("MTparseObject() failed");
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delay(10000);
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__wferrno=-2; // set the error code
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return NULL;
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}
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if (Debug&&Debugplus) Serial.println("Beauty print...");
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if (Debug&&Debugplus) _root.prettyPrintTo(Serial); // print it on prettyPrint format
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if (Debug&&Debugplus) Serial.println("END of Beauty print...");
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JsonObject & _ooo = _root["weatherObservation"]; // query root
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MET->MTobservation = _ooo ["observation"]; // raw observation
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MET->MTtemp = _ooo ["temperature"]; // temp
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MET->MTpressure = _ooo ["hectoPascAltimeter"]; // QNH
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MET->MTQNH = _ooo ["hectoPascAltimeter"]; // QNH
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MET->MTdewpoint = _ooo ["dewPoint"]; // Dew point
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MET->MThumidity = _ooo ["humidity"]; // humidity %
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MET->MTwinddeg = _ooo ["windDirection"]; // wind
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MET->MTwindspeed = _ooo ["windSpeed"]; // speed
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MET->MTobservationtime= _ooo ["datetime"]; // time
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## Example 3: iterators
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### JsonArray
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```c++
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char json[] = "[\"A\",\"B\",\"C\"]";
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JsonArray& array = jsonBuffer.parseArray(json);
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for(JsonArray::iterator it=array.begin(); it!=array.end(); ++it)
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{
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// *it contains the JsonVariant which can be casted as usuals
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const char* value = *it;
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// this also works:
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value = it->as<const char*>();
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}
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```
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### JsonObject
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```c++
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char json[] = "{\"key\":\"value\"}";
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JsonObject& object = jsonBuffer.parseObject(json);
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for(JsonObject::iterator it=object.begin(); it!=object.end(); ++it)
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{
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// *it contains the key/value pair
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const char* key = it->key;
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// it->value contains the JsonVariant which can be casted as usual
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const char* value = it->value;
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// this also works
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value = it->value.as<const char*>();
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}
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```
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### JsonVariant
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for an object:
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```c++
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for( const auto& kv : variant.as<JsonObject>() ) {
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Serial.println(kv.key);
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Serial.println(kv.value.as<char*>());
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}
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```
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and for an array:
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```c++
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for( const auto& value : variant.as<JsonArray>() ) {
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Serial.println(value.as<char*>());
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}
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```
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## Example 4: Serialize and Deserialize
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Here is the canonical example for serializing and deserializing with ArduinoJson.
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By following this example, you are making the best usage of your memory and you maintain a good software design.
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```c++
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struct SensorData {
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const char* name;
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int time;
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float value;
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};
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#define SENSORDATA_JSON_SIZE (JSON_OBJECT_SIZE(3))
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bool deserialize(SensorData& data, char* json)
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{
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StaticJsonBuffer<SENSORDATA_JSON_SIZE> jsonBuffer;
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JsonObject& root = jsonBuffer.parseObject(json);
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data.name = root["name"];
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data.time = root["time"];
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data.value = root["value"];
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return root.success();
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}
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void serialize(const SensorData& data, char* json, size_t maxSize)
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{
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StaticJsonBuffer<SENSORDATA_JSON_SIZE> jsonBuffer;
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JsonObject& root = jsonBuffer.createObject();
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root["name"] = data.name;
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root["time"] = data.time;
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root["value"] = data.value;
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root.printTo(json, maxSize);
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}
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```
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