Feature request :: Better testing for key existance without try/catch

[mlfarrell]

Correct me if I'm wrong, but using a const json obj + .at() + try/catch is the only way safe to test for object key exists. This seems REALLY brutal compared to the ease of use using the rest of the library

Perhaps there'd be some way to return a bool operator comparable for object gets along the lines of

if(auto possibleVal = json["maybeExists"])
{
  //possibleVal exists
}

or.. at the very least, a .exists(const std::string &) method would be helpful..

[pboettch]

You can use find():

nlohmann::json instance; 
// [..] fill instance
auto field = instance.find("id");
if (field == instance.end()) {
    std::cerr << "id not found\n";
} else {
    std::cerr << "value of id " << field.value() << "\n";
}

[nlohmann]

Here is the documentation for find: https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a89eb3928f57903677051c80534be9cb1.html#a89eb3928f57903677051c80534be9cb1

[nlohmann]

@mlfarrell Do you need further assistance?

[mlfarrell]

No this will help. Thanks!