ARDUINOJSON_ENABLE_STRING_VIEW

The macro ARDUINOJSON_ENABLE_STRING_VIEW controls the support of the type std::string_view in the library.

If ARDUINOJSON_ENABLE_STRING_VIEW is defined to 1, then std::string_view is supported.

This features was added in ArduinoJson 6.18.1.

Default value

ArduinoJson can detect the presence of the <string_view> header. The default value of ARDUINOJSON_ENABLE_STRING_VIEW is:

If for some reason, you need to force the support of std::string_view, add the following line at the top of your program:

#define ARDUINOJSON_ENABLE_STRING_VIEW 1
#include <ArduinoJson.h>

If you need to disable the support for std::string_view, add the following line at the top of your program:

#define ARDUINOJSON_ENABLE_STRING_VIEW 0
#include <ArduinoJson.h>

Only 0 and 1 are valid. Any other value (like false or true) will produce a compilation error.

Once enabled, you can use a std::string_view in many places.

As your JSON input:

 // WARNING: ArduinoJson duplicates the std::string in the JsonDocument
 deserializeJson(doc, std::string_view("{\"sensor\":\"gps\"}", 16));

As a value:

 doc["sensor"] = std::string_view("gps", 3);

As a key to extract a member from a JsonDocument:

 const char* sensor = doc[std::string_view("sensor", 6)];

As a key to insert a member in a JsonDocument:

 doc[std::string_view("time", 4)] = time;

You can compare the content of a JsonVariant with a std::string_view

 if (doc["sensor"] == std::string_view("gps", 3)) {
     // ...
 }