void ReadDataListen()

in firestore/android/FirestoreSnippetsCpp/app/src/main/cpp/snippets.cpp [603:627]

• 18 lines of code
• 3 McCabe index (conditional complexity)

void ReadDataListen(firebase::firestore::Firestore* db) {
  using firebase::firestore::DocumentReference;
  using firebase::firestore::DocumentSnapshot;
  using firebase::firestore::Error;

  // You can listen to a document with the AddSnapshotListener() method. An
  // initial call using the callback you provide creates a document snapshot
  // immediately with the current contents of the single document. Then, each
  // time the contents change, another call updates the document snapshot.
  // [START listen_document]
  DocumentReference doc_ref = db->Collection("cities").Document("SF");
  doc_ref.AddSnapshotListener(
      [](const DocumentSnapshot& snapshot, Error error, const std::string& errorMsg) {
        if (error == Error::kErrorOk) {
          if (snapshot.exists()) {
            std::cout << "Current data: " << snapshot << std::endl;
          } else {
            std::cout << "Current data: null" << std::endl;
          }
        } else {
          std::cout << "Listen failed: " << error << std::endl;
        }
      });
  // [END listen_document]
}