Here is the code for when I'm pushing the data to Firebase:
firebase.database().ref(`booklogs/${uid}/${book_id}`).push(page_id)
booklogs :
{HUMjSHxVKAPfVXzOId9zCBkGOgv1:{
book28917: {
-KYp4FdYYODDZG1FX-Pb: 1
}
}
}
My problem is when I query the data, the child node of the ${book_id} includes the push key, but I only want to get the value which is 1 and not the push key.
The code I use to query is:
var booklogs = db.ref(`booklogs/${uid}/${project}`);
booklogs.once('value')
.then((snapshot) => {
console.log(`pages viewed are ${snapshot.key}: ${snapshot.val()}`);
console.dir(snapshot.val());
}).catch((error) => {
console.log(`Error : ${error}`);
});
The data returned in the console is:
pages viewed are 2634651: [object Object]
{ '-KYp4FdYYODDZG1FX-Pb': 1 }
Any input would be much appreciated. Thanks!
If you only want the '1' and not the push key, try using .set()
firebase.database().ref(`booklogs/${uid}/${book_id}`).set(page_id)
That will get rid of the object and just give you the value that you wanted. Push automatically generates a key for every value you add, so you will always get an object back. From the Firebase docs - "For basic write operations, you can use set() to save data to a specified reference, replacing any existing data at that path."
https://firebase.google.com/docs/database/web/read-and-write
Related
I have array of data (selected items) and I need to extract ids of this array into new array so I can send those ids only to back-end.
Code
method
toggleSelection(rows) {
console.log('this.multipleSelection : ',this.multipleSelection); // prints my default array (include all data)
this.multipleSelection.forEach(row => {
console.log('rows: ', row) // get each object of array (extract ids here)
// send axios request to backend (ids only)
});
},
Screenshot
here is result of console codes above
any idea?
At first I need to say I never worked with Vue.js. But in simple vanilla-javascript you could use the map function. I don't know if this works but Here is a possible answer:
yourids = this.multipleSelection.map(row => row.id);
Im using the following loop to get data from a table which is working fine:
database.once("value", function(snapshot){
snapshot.forEach(snap => {
log.console(snap.val().about_me)
})
Its displaying the data to logs as expected, But i can't seem to get the object id?
I need to get the value 49GRZb8B31MUfpBN3zvHKOHCMOa2
I have tried:
snap.val().key;
This returns undefined
And have tried snap.val()[0];
which returns me everything in the object
snap is a DataSnapshot type object. You can see that it has a property called key. So, you need to reference that property directly on the DataSnapshot like this:
snap.key // correct
But not via the raw data object like this:
snap.val().key // incorrect, you have no child named 'key' in your data
I am using Firebase to store information for a workout application.
I user adds a workout name and then I push it to the database. I can continue pushing these but my issue is that it does not seem to be pushing as an array just an object. See the screen shots below...
As you can see in the console log picture the workouts property is an object not an array like I expect.
The code I'm using to push it:
let newWorkout = {
title: 'title',
exercises: [{
name: 'pulldownsnsn',
sets: 4
}]}
let ref = firebase.database().ref("/userProfile/"+this.userId);
ref.child("workouts").push(newWorkout);
The Firebase Database stores lists of data in a different format, to cater for the multi-user and offline aspects of modern web. The -K... are called push IDs and are the expected behavior when you call push() on a database reference.
See this blog post on how Firebase handles arrays, this blog post on the format of those keys, and the Firebase documentation on adding data to lists.
Arrays are handy, but they are a distributed database nightmare for one simple reason: index element identification is not reliable when elements get pushed or deleted. Firebase database instead uses keys for element identification:
// javascript object
['hello', 'world']
// database object
{ -PKQdFz22Yu: 'hello', -VxzzHd1Umr: 'world' }
It gets tricky when using push(), because it does not actually behaves like a normal push, but rather as a key generation followed by object modification.
Example usage
firebase.database().ref('/uri/to/list').push(
newElement,
err => console.log(err ? 'error while pushing' : 'successful push')
)
Heres an example from firebase documentation:
const admin = require('firebase-admin');
// ...
const washingtonRef = db.collection('cities').doc('DC');
// Atomically add a new region to the "regions" array field.
const unionRes = await washingtonRef.update({
regions: admin.firestore.FieldValue.arrayUnion('greater_virginia')
});
// Atomically remove a region from the "regions" array field.
const removeRes = await washingtonRef.update({
regions: admin.firestore.FieldValue.arrayRemove('east_coast')
});
More info on this firebase documentation.
Anyone know how to get the Firebase unique id? I've tried name(), name, key, key(). Nothing works.
I am able to see the data but I have no idea how to get the id back. I need it.
//Create new customers into firebase
function saveCustomer(email) {
firebase.database().ref('/customers').push({
email: email
});
firebase.database().ref('/customers').on("value", function(snapshot) {
console.log(snapshot.val());
console.log(snapshot.value.name());
}, function(errorObject) {
console.log("The read failed: " + errorObject.code);
});
}
The call to push will return a Firebase reference. If you are using the Firebase 3 API, you can obtain the unique key of the pushed data from the reference's key property:
var pushedRef = firebase.database().ref('/customers').push({ email: email });
console.log(pushedRef.key);
The key for the pushed data is generated on the client - using a timestamp and random data - and is available immediately.
Calling push() will return a reference to the new data path, which you can use to get the value of its ID or set data to it.
The following code will result in the same data as the above example, but now we'll have access to the unique push ID that was generated:
// Generate a reference to a new location and add some data using push()
var newPostRef = postsRef.push();
// Get the unique ID generated by push()
var postID = newPostRef.key();
Documentation.
but this method won't work when you also need the id beforehand
for example to save it in the database itself.
Firebase suggests this:
// Add a new document with a generated id.
var newCityRef = db.collection("cities").doc();
--for some reason, push() and key() didn't work for me. also in this case the reference contains the whole path. so need a different method for getting the id.
Doing this below helped to get the id from the reference and use it.
const ref = db.collection('projects').doc()
console.log(ref.id) // prints the unique id
ref.set({id: ref.id}) // sets the contents of the doc using the id
.then(() => { // fetch the doc again and show its data
ref.get().then(doc => {
console.log(doc.data()) // prints {id: "the unique id"}
})
})
See the sample code below - in this case, the objectId for the record I am trying to retrieve is known.
My question is, if I don't know the Parse.com objectId, how would I implement the code below?
var Artwork = Parse.Object.extend("Artwork");
var query = new Parse.Query(Artwork);
query.get(objectId, {
success: function(artwork) {
// The object was retrieved successfully.
// do something with it
},
error: function(object, error) {
// The object was not retrieved successfully.
// warn the user
}
});
Query.get() is used when you already know the Parse object id.
Otherwise, one can use query.find() to get objects based on the query parameters.
Sure, you can use Parse Query to search for objects based on their properties.
The thing that wasn't clear to me in the documentation is that once you get the object in the query, you would need to do:
With Query (can return multiple objects):
artwork[0].get('someField');
With 'first' or 'get':
artwork.get('someField');
You cannot do something like artwork.someField like I assumed you would