Call a Function - C++ SDK Preview

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Call a Function By Name

The examples on this page demonstrate calling an Atlas Function named concatenate that takes two arguments, concatenates them, and returns the result:

// concatenate: concatenate two strings
exports = function(a, b) {
  return a + b;
};

Call a Function By Name

Important

Make sure to sanitize client data to protect against code injection when using Functions.

To execute a function from the C++ SDK, use the call_function() member function on the user object. Pass in the name of the function as a string for the first parameter. This function takes two arguments, which we provide as a BsonArray of arguments:

Changed in version 0.2.0: Returns std::future instead of std::promise

// Connect to an App Services App and authenticate a user
auto app = realm::App(APP_ID);
auto user = app.login(realm::App::credentials::anonymous()).get();
auto sync_config = user.flexible_sync_configuration();
// If a function takes arguments, pass them as BSON
auto arg1 = realm::bson::Bson("john.smith");
auto arg2 = realm::bson::Bson("@companyemail.com");
// Call an App Services function as the logged-in user
auto result = user.call_function("concatenate", { arg1, arg2 }).get();
// Verify that the result has a value
CHECK(result);
auto bsonResult = result.value();
// Translate the BSON result back to a string
auto resultString = std::string(bsonResult);
// Prints "Calling the concatenate function returned john.smith@companyemail.com."
std::cout << "Calling the concatenate function returned " << resultString << ".\n";

The callback can provide an optional BSON result, or an optional error. In the example above, we check that the result has a value, and then cast it back to a string.

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