in an Android app I have the following:
notebookRef = FirebaseFirestore.getInstance().collection("Registros");
notebookRef.add(new Lista(title, description, geoPoint, null));
Map<String, Object> value = new HashMap<>();
value.put("timestamp", ServerValue.TIMESTAMP);
notebookRef.add(value);
it go mad because instead of generating a timestamp it write the following in the firebase:
the server should generate its own timestamp: see here and here
what am I doing wrong?
You're incorrectly using the ServerValue.TIMESTAMP from Realtime Database instead of FieldValue.serverTimestamp() for Firestore.
Related
I am trying to add a timestamp field in an Android client with Firebase Firestore.
According to the documentation:
Annotation used to mark a Date field to be populated with a server
timestamp. If a POJO being written contains null for a
#ServerTimestamp-annotated field, it will be replaced with a
server-generated timestamp.
But when I try it:
#ServerTimestamp
Date serverTime = null; // I tried both java.util.Date and java.sql.Date
//...
Map<String, Object> msg = new HashMap<>();
// ... more data
msg.put("timestamp", serverTime);
On the Cloud Firestore database this field is always null.
That is not the correct way of how to add the time and date to a Cloud Firestore database. The best practice is to have a model class in which you can add a date field of type Date together with an annotation. This is how your model class should look like:
import java.util.Date;
public class YourModelClass {
#ServerTimestamp
private Date date;
YourModelClass() {}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
}
When you create on object of YourModelClass class, there is no need to set the date. Firebase servers will read your date field, as it is a ServerTimestamp (see the annotation), and it will populate that field with the server timestamp accordingly.
Another approach would be to use FieldValue.serverTimestamp() method like this:
Map<String, Object> map = new HashMap<>();
map.put("date", FieldValue.serverTimestamp());
docRef.update(map).addOnCompleteListener(new OnCompleteListener<Void>() {/* ... */}
use FieldValue.serverTimestamp() get server timestamp
Map<String, Object> msg = new HashMap<>();
msg.put("timestamp", FieldValue.serverTimestamp());
I have similar problem, and I found this at my catlog and solved my problem
firebaseFirestore = FirebaseFirestore.getInstance();
FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder()
.setTimestampsInSnapshotsEnabled(true)
.build();
firebaseFirestore.setFirestoreSettings(settings);
I had a similar problem,
I was getting the exception ...has type java.sql.Timestamp, got java.util.Date ..., so I just replace the type from Timestamp to Date ( from java.util.Date) and worked fine.
My app will generate a gameKey everytime user logged in and clicked "start game" button. Variable "gameKey" is generated by the following code, and then I will save data under the gameKey. The problem is, whenever I restart my app, the Firebase replaced the whole data tree with a new gameKey generated.
What I would like to do is to generate a new gameKey without overwriting the old data every time when my app runs. It would be so glad if anyone can point out my problem, thanks so much!
final FirebaseDatabase database = FirebaseDatabase.getInstance();
UserId = mAuth.getCurrentUser().getUid();
DatabaseReference currentUserId = database.getReference("user").child(UserId);
gameKey = currentUserId.child("gameinfo").push().getKey();
Map<String, Object> game = new HashMap<>();
game.put(gameKey, new Game(tv_player1name.getText().toString(), tv_player2name.getText().toString(), tv_player3name.getText().toString(), tv_playerMename.getText().toString(), gameMode, gameDate ));
currentUserId.child("gameInfo").updateChildren(game);
Firebase Data:
- user
- 5xGKRXeHgThQy70lduPEp3mosTj1 (UID)
- gameInfo
-LLV0H0ZJwYT5M42Obfb
gameDate: "20180903_232015"
gameType: "HKMJ"
player1name: "peter"
player2name: "jenny"
player3name: "john"
player4name: "wilson"
*This is the gameKey generated: "LLV0H0ZJwYT5M42Obfb"
This is the code after your suggestions:
final FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference currentUserId = database.getReference("user").child(UserId);
currentUserId.setValue(new User(mAuth.getCurrentUser().getEmail(), UserPic));
gameKey = currentUserId.child("gameinfo").push().getKey();
Map<String, Object> game = new HashMap<>();
game.put(gameKey, new Game(tv_player1name.getText().toString(), tv_player2name.getText().toString(), tv_player3name.getText().toString(), tv_playerMename.getText().toString(), gameMode, gameDate ));
currentUserId.child("gameInfo").child(gameKey).updateChildren(game);
In addition, I tried to replace this line
game.put(gameKey, new Game(tv_player1name.getText().toString(), tv_player2name.getText().toString(), tv_player3name.getText().toString(), tv_playerMename.getText().toString(), gameMode, gameDate ));
with this line, same result
Game game = new Game(tv_player1name.getText().toString(), tv_player2name.getText().toString(), tv_player3name.getText().toString(), tv_playerMename.getText().toString(), gameMode, gameDate );
Appreciate so much for the help!
Firebase ScreenShot
To solve this, please change the following line of code:
currentUserId.child("gameInfo").updateChildren(game);
to
currentUserId.child("gameInfo").child(gameKey).updateChildren(game);
You are basically generating a random key but you aren't using it at all. So you need to pass the gameKey to the child() method as seen in my above code.
Edit: So solve the entire update process, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference gameInfoRef = rootRef.child("user").child(uid).child("gameInfo");
String key = gameInfoRef.push().getKey();
Map<String, Object> game = new HashMap<>();
game.put("player1name", tv_player1name.getText().toString());
game.put("player2name", tv_player2name.getText().toString());
game.put("player3name", tv_player3name.getText().toString());
game.put("playerMename", tv_playerMename.getText().toString());
game.put("gameMode", gameMode);
game.put("gameDate", gameDate);
gameInfoRef.child(key).updateChildren(game);
May I ask if there is any implementation to collect the time when the first data is updated. For example, there is a queue function in my app. When an user has taken the queue ticket, Firebase will then be updated.
Therefore, I would like to know the time that the first user in the queue.
Is there any code for this in Android Studio? Many thanks!!
The Firebase Database does not store metadata (informations like the timestamp) for CRUD operations that are performed. Because of that, you need to store this kind of data yourself by creating your own mechanism.
In fact, you need to create a new field for each child you want to trace and change the value of the timestamp every time a action is performed. The best practice within a Firebase database is to save your data as a timestamp using: ServerValue.TIMESTAMP.
Note, that when you are saving the timestamp, you are saving as a Map and when you are retrieving, you are retrieving it as a long.
To set the timestamp, I recommend you to use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Map<String, Object> map = new HashMap<>();
map.put("timestamp", ServerValue.TIMESTAMP);
rootRef.child("yourNode").updateChildren(map);
To get you data back, I recommend you using the following method:
public static String getTimeDate(long timeStamp){
try{
DateFormat dateFormat = getDateTimeInstance();
Date netDate = (new Date(timeStamp));
return dateFormat.format(netDate);
} catch(Exception e) {
return "date";
}
}
Let's say I have this JSON tree:
"employees":[
{"firstName":"John", "lastName":"Doe"},
{"firstName":"Anna", "lastName":"Smith"},
{"firstName":"Peter","lastName":"Jones"}
]
How can I do this in Firebase? Every time I create an object under "employees", with the name "firstname", it replaces the previous object with "Firstname".
I previously used Parse's tables, but since it's been taken down, then I need help learning this confusing thing.
I'm using Android.
Firebase databases have no native support for lists or arrays. If we try to store an list or an array, it really gets stored as an "object" with integers as the key names (see doc).
// we send this
['hello', 'world']
// Firebase databases store this
{0: 'hello', 1: 'world'}
In this way your tree in firebase would look like this:
{"employees":{
0:{"firstName":"John", "lastName":"Doe"},
1:{"firstName":"Anna", "lastName":"Smith"},
2:{"firstName":"Peter","lastName":"Jones"}
}
}
Using Firebase terminology we can say that node emloyees has three child nodes with IDs 0,1,2 respectively.
But saving data with integer IDs in Firebase is not recommended (see this to know why). Firebase provides a push() function that generates a unique ID every time a new child is added to the specified Firebase reference.
Here is an example from Firebase Android doc.:
//create firebase ref using your firebase url
Firebase ref = new Firebase("https://docs-examples.firebaseio.com/android/saving-data/fireblog");
Firebase postRef = ref.child("posts");
Map<String, String> post1 = new HashMap<String, String>();
post1.put("author", "gracehop");
post1.put("title", "Announcing COBOL, a New Programming Language");
postRef.push().setValue(post1);
Map<String, String> post2 = new HashMap<String, String>();
post2.put("author", "alanisawesome");
post2.put("title", "The Turing Machine");
postRef.push().setValue(post2);
And as a result in posts node we will have two childs with autogenerated ids:
{
"posts": {
"-JRHTHaIs-jNPLXOQivY": {
"author": "gracehop",
"title": "Announcing COBOL, a New Programming Language"
},
"-JRHTHaKuITFIhnj02kE": {
"author": "alanisawesome",
"title": "The Turing Machine"
}
}
}
You're probably looking for DatabaseReference.push(), which creates a new child under the location.
var employeesRef = mDatabase.child("employees");
var newEmployeeRef = employeesRef.push()
newEmployeeRef.setValue(employee);
The best place to read more about this is in the section on appending data to a list in the Firebase documentation.
I have this code in my Android application, creating a new record in Firebase.
Firebase searchRef = myFirebaseRef.child("searches");
Firebase newPostRef = searchRef.push();
Map<String, String> search = new HashMap<String, String>();
search.put("start", start_address);
newPostRef.setValue(search);
String postId = newPostRef.getKey();
How would I go about inserting the ServerValue.TIMESTAMP into this record?
Use the below code to set the timestamp to a particular node
setValue(ServerValue.TIMESTAMP);