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76 lines
2.6 KiB
76 lines
2.6 KiB
// ArduinoJson - https://arduinojson.org |
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// Copyright © 2014-2024, Benoit BLANCHON |
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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/v7/example/string/ |
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#include <ArduinoJson.h> |
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void setup() { |
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JsonDocument doc; |
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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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// You can use a String as a key to get a member from JsonDocument |
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// No duplication is done. |
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long time = doc[String("time")]; |
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// You can use a String as a key to set a member of a JsonDocument |
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// WARNING: the content of the String will be duplicated in the JsonDocument. |
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doc[String("time")] = time; |
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// You can get the content of a JsonVariant as a String |
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// No duplication is done, at least not in the JsonDocument. |
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String sensor = doc["sensor"]; |
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// Unfortunately, the following doesn't work (issue #118): |
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// sensor = doc["sensor"]; // <- error "ambiguous overload for 'operator='" |
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// As a workaround, you need to replace by: |
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sensor = doc["sensor"].as<String>(); |
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// You can set a String as the content of a JsonVariant |
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// WARNING: the content of the String will be duplicated in the JsonDocument. |
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doc["sensor"] = sensor; |
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// It works with serialized() too: |
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doc["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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doc[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 (doc["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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