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78 lines
2.6 KiB
78 lines
2.6 KiB
3 years ago
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// ArduinoJson - https://arduinojson.org
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// Copyright Benoit Blanchon 2014-2021
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// MIT License
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//
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// This example shows the different ways you can use String with ArduinoJson.
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//
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// Use String objects sparingly, because ArduinoJson duplicates them in the
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// JsonDocument. Prefer plain old char[], as they are more efficient in term of
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// code size, speed, and memory usage.
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//
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// https://arduinojson.org/v6/example/string/
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#include <ArduinoJson.h>
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void setup() {
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DynamicJsonDocument doc(1024);
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// You can use a String as your JSON input.
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// WARNING: the string in the input will be duplicated in the JsonDocument.
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String input =
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"{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";
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deserializeJson(doc, input);
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JsonObject obj = doc.as<JsonObject>();
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// You can use a String to get an element of a JsonObject
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// No duplication is done.
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long time = obj[String("time")];
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// You can use a String to set an element of a JsonObject
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// WARNING: the content of the String will be duplicated in the JsonDocument.
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obj[String("time")] = time;
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// You can get a String from a JsonObject or JsonArray:
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// No duplication is done, at least not in the JsonDocument.
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String sensor = obj["sensor"];
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// Unfortunately, the following doesn't work (issue #118):
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// sensor = obj["sensor"]; // <- error "ambiguous overload for 'operator='"
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// As a workaround, you need to replace by:
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sensor = obj["sensor"].as<String>();
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// You can set a String to a JsonObject or JsonArray:
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// WARNING: the content of the String will be duplicated in the JsonDocument.
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obj["sensor"] = sensor;
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// It works with serialized() too:
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obj["sensor"] = serialized(sensor);
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// You can also concatenate strings
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// WARNING: the content of the String will be duplicated in the JsonDocument.
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obj[String("sen") + "sor"] = String("gp") + "s";
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// You can compare the content of a JsonObject with a String
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if (obj["sensor"] == sensor) {
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// ...
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}
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// Lastly, you can print the resulting JSON to a String
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String output;
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serializeJson(doc, output);
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}
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void loop() {
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// not used in this example
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}
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// See also
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// --------
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//
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// https://arduinojson.org/ contains the documentation for all the functions
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// used above. It also includes an FAQ that will help you solve any problem.
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//
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// The book "Mastering ArduinoJson" contains a quick C++ course that explains
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// how your microcontroller stores strings in memory. On several occasions, it
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// shows how you can avoid String in your program.
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// Learn more at https://arduinojson.org/book/
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// Use the coupon code TWENTY for a 20% discount ❤❤❤❤❤
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