Child value = null
I have a database that looks like this:
database
|
places
|
user1
| |___indoors: "yes"
| |___outdoors: "yes"
|
user2
|___indoors: "yes"
|___outdoors: "no"
When I do the following, I get all users places information as a single object (converted to String) with no problems:
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String locations = dataSnapshot.toString(); // I get the entire tree as String
}
}
//this is how I set the listener to changes
DatabaseReference database = FirebaseDatabase.getInstance().getReference();
DatabaseReference reference = database.child("places");
reference.addValueEventListener(placesListener);
But, when I want only the indoors children, I get DataSnapshot {key = indoors, value = null}.
This is how I try to get only the indoors keys and values (almost the same, only adding extra .child("indoors"):
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String indoors = dataSnapshot.child("indoors").toString(); // I get value = null
}
}
// listener remains the same
android firebase firebase-realtime-database edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
add a comment |
I have a database that looks like this:
database
|
places
|
user1
| |___indoors: "yes"
| |___outdoors: "yes"
|
user2
|___indoors: "yes"
|___outdoors: "no"
When I do the following, I get all users places information as a single object (converted to String) with no problems:
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String locations = dataSnapshot.toString(); // I get the entire tree as String
}
}
//this is how I set the listener to changes
DatabaseReference database = FirebaseDatabase.getInstance().getReference();
DatabaseReference reference = database.child("places");
reference.addValueEventListener(placesListener);
But, when I want only the indoors children, I get DataSnapshot {key = indoors, value = null}.
This is how I try to get only the indoors keys and values (almost the same, only adding extra .child("indoors"):
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String indoors = dataSnapshot.child("indoors").toString(); // I get value = null
}
}
// listener remains the same
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
add a comment |
I have a database that looks like this:
database
|
places
|
user1
| |___indoors: "yes"
| |___outdoors: "yes"
|
user2
|___indoors: "yes"
|___outdoors: "no"
When I do the following, I get all users places information as a single object (converted to String) with no problems:
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String locations = dataSnapshot.toString(); // I get the entire tree as String
}
}
//this is how I set the listener to changes
DatabaseReference database = FirebaseDatabase.getInstance().getReference();
DatabaseReference reference = database.child("places");
reference.addValueEventListener(placesListener);
But, when I want only the indoors children, I get DataSnapshot {key = indoors, value = null}.
This is how I try to get only the indoors keys and values (almost the same, only adding extra .child("indoors"):
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String indoors = dataSnapshot.child("indoors").toString(); // I get value = null
}
}
// listener remains the same
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
I have a database that looks like this:
database
|
places
|
user1
| |___indoors: "yes"
| |___outdoors: "yes"
|
user2
|___indoors: "yes"
|___outdoors: "no"
When I do the following, I get all users places information as a single object (converted to String) with no problems:
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String locations = dataSnapshot.toString(); // I get the entire tree as String
}
}
//this is how I set the listener to changes
DatabaseReference database = FirebaseDatabase.getInstance().getReference();
DatabaseReference reference = database.child("places");
reference.addValueEventListener(placesListener);
But, when I want only the indoors children, I get DataSnapshot {key = indoors, value = null}.
This is how I try to get only the indoors keys and values (almost the same, only adding extra .child("indoors"):
ValueEventListener placesListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String indoors = dataSnapshot.child("indoors").toString(); // I get value = null
}
}
// listener remains the same
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
edited Nov 15 '18 at 9:54
Grimthorr
4,47442236
4,47442236
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
asked Nov 15 '18 at 9:03
TTnoteTTnote
969
969
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
The data contained in a DataSnapshot is relative, like a JSON tree. From the documentation on DataSnapshot#child():
Get a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. 'fred') or a deeper slash-separated path (e.g. 'fred/name/first'). If the child location has no data, an empty DataSnapshot is returned.
In your example, there is no child named indoors directly under the places node. Instead, you have 2 children named user1 and user2 which each have a child named indoors. Therefore, in order to access one of the indoors children, you'll need to do something like:
dataSnapshot.child("user1").child("indoors").toString();
Alternatively, you can iterate through the children using:
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
Log.d(childSnapshot.getKey() + ": indoors=" + childSnapshot.child("indoors").toString());
}
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
add a comment |
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1 Answer
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oldest
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
The data contained in a DataSnapshot is relative, like a JSON tree. From the documentation on DataSnapshot#child():
Get a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. 'fred') or a deeper slash-separated path (e.g. 'fred/name/first'). If the child location has no data, an empty DataSnapshot is returned.
In your example, there is no child named indoors directly under the places node. Instead, you have 2 children named user1 and user2 which each have a child named indoors. Therefore, in order to access one of the indoors children, you'll need to do something like:
dataSnapshot.child("user1").child("indoors").toString();
Alternatively, you can iterate through the children using:
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
Log.d(childSnapshot.getKey() + ": indoors=" + childSnapshot.child("indoors").toString());
}
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
add a comment |
The data contained in a DataSnapshot is relative, like a JSON tree. From the documentation on DataSnapshot#child():
Get a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. 'fred') or a deeper slash-separated path (e.g. 'fred/name/first'). If the child location has no data, an empty DataSnapshot is returned.
In your example, there is no child named indoors directly under the places node. Instead, you have 2 children named user1 and user2 which each have a child named indoors. Therefore, in order to access one of the indoors children, you'll need to do something like:
dataSnapshot.child("user1").child("indoors").toString();
Alternatively, you can iterate through the children using:
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
Log.d(childSnapshot.getKey() + ": indoors=" + childSnapshot.child("indoors").toString());
}
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
add a comment |
The data contained in a DataSnapshot is relative, like a JSON tree. From the documentation on DataSnapshot#child():
Get a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. 'fred') or a deeper slash-separated path (e.g. 'fred/name/first'). If the child location has no data, an empty DataSnapshot is returned.
In your example, there is no child named indoors directly under the places node. Instead, you have 2 children named user1 and user2 which each have a child named indoors. Therefore, in order to access one of the indoors children, you'll need to do something like:
dataSnapshot.child("user1").child("indoors").toString();
Alternatively, you can iterate through the children using:
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
Log.d(childSnapshot.getKey() + ": indoors=" + childSnapshot.child("indoors").toString());
}
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
The data contained in a DataSnapshot is relative, like a JSON tree. From the documentation on DataSnapshot#child():
Get a DataSnapshot for the location at the specified relative path. The relative path can either be a simple child key (e.g. 'fred') or a deeper slash-separated path (e.g. 'fred/name/first'). If the child location has no data, an empty DataSnapshot is returned.
In your example, there is no child named indoors directly under the places node. Instead, you have 2 children named user1 and user2 which each have a child named indoors. Therefore, in order to access one of the indoors children, you'll need to do something like:
dataSnapshot.child("user1").child("indoors").toString();
Alternatively, you can iterate through the children using:
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
Log.d(childSnapshot.getKey() + ": indoors=" + childSnapshot.child("indoors").toString());
}
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
answered Nov 15 '18 at 9:51
GrimthorrGrimthorr
4,47442236
4,47442236
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
add a comment |
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Thank you. By the way, is there a way to retrieve data from the Firebase database NOT in real time? I just want a specific value but get it now, and not in real time
– TTnote
Nov 15 '18 at 9:56
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
Glad to help. Do you mean synchronously? Not exactly, as this isn't a supported feature of Firebase, but there are options, see Is it possible to synchronously load data from Firebase? for more details.
– Grimthorr
Nov 15 '18 at 9:59
add a comment |
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