How to search for specific value in DataSnapshot with Firebase cloud features
I am trying to create a cloud function that will be triggered on an HTTP request (which is sent on a timer) that will remove all children with a specific value.
The node database looks like this:
activities
4GI1QXUJG0MeQ8Bq19WOdCQFo9r1 //uid
activity: "hammer"
id: some ID
note: "some note"
timestamp: some timeintervalsince1970
7IDUiufhiws8939hdfIUHiuhwdi5
etc....
I want to view all activities, and if the activity value is "hammer", I want to delete it.
This is what I still have
exports.deleteHammerNotifications = functions.https.onRequest((req, res) => {
admin.database().ref('activities').once('value', (snapshot) => {
console.log(snapshot.val())
});
});
which prints:
{
'4GI1QXUJG0MeQ8Bq19WOdCQFo9r1':
{ activity: 'nn',
id: '4GI1QXUJG0MeQ8Bq19WOdCQFo9r1',
note: 'Blank note...',
timestamp: 1498032472 },
M6xQU5XWTEVbSqBnR3HBAEhA9hI3:
{ activity: 'hammer',
id: 'M6xQU5XWTEVbSqBnR3HBAEhA9hI3',
note: 'some note here...',
timestamp: 1497973839 },
}
My problem is that I don't know how to loop through the DataSnapshot and search for all children that have an activity: hammer value. I made a similar function in my xcode project with arrays, but I don't know how to do it using JavaScript.
Any help is appreciated!
source to share
To loop through the appropriate child nodes use snapshot.forEach()
:
exports.deleteHammerNotifications = functions.https.onRequest((req, res) => {
admin.database().ref('activities').once('value', (snapshot) => {
snapshot.forEach((childSnapshot) => {
console.log(childSnapshot.val())
});
});
});
But you still haven't specified a prompt here to select the correct nodes. Without such a request, you can also call admin.database().ref('activities').remove()
.
To most efficiently remove multiple items from the database and write one response back to the user, use this function (which I changed from something I needed lately):
exports.cleanup = functions.https.onRequest((req, res) => {
var query = admin.database().ref("activities").orderByChild("activity").equalTo("hammer");
query.once("value").then((snapshot) => {
console.log("cleanup: "+snapshot.numChildren()+" activities");
var updates = {};
snapshot.forEach((child) => {
updates["activities/"+child.key] = null;
});
admin.database().ref().update(updates).then(() => {
res.status(200).send(snapshot.numChildren()+" activities deleted");
}).catch((error) => {
res.status(500).send(error);
})
});
});
More details:
source to share
I'm not sure if this is possible, but if you can trigger the "child_added" listener, after the HTTPS trigger has run, you can do it.
ref.on('child_added', function(snapshot) {
if (snapshot.child("activity").val() === 'hammer') {
var value = snapshot.child("activity").val();
})
I do the same to find out if all people are subscribing to my mailing list or not, and if they are, they will receive mail.
Hope it helps :-)
source to share