从c++中firestore中的文档中获取字段值

#include <firebase/firestore.h>

using firebase::firestore::DocumentSnapshot;
using firebase::firestore::FieldValue;

firebase::App* app = firebase::App::Create(firebase::AppOptions());
firebase::firestore::Firestore* firestore = firebase::firestore::Firestore::GetInstance(app);

firebase::firestore::CollectionReference collection_ref = firestore->Collection("collection_name");
firebase::firestore::DocumentReference document_ref = collection_ref.Document("document_id");

DocumentSnapshot snapshot = document_ref.Get().value();

FieldValue field_value = snapshot.Get("field_name");

std::string field_string = field_value.string_value();

int field_integer = field_value.integer_value();

bool field_boolean = field_value.boolean_value();

double field_double = field_value.double_value();

firebase::Timestamp field_timestamp = field_value.timestamp_value();