I am trying to create a "Users" list. But I am not able to replicate the way it is structured in the docs https://www.firebase.com/images/data_structure.png.
Instead my structure has a Users with child nodes having some raw text. https://www.evernote.com/shard/s52/sh/21c878d6-4978-440c-a089-10da4fb6d792/2d0d7a90861ef6f94e425fdb904b8ab2 Instead I want child nodes named as 'john','terry' etc as shown in your docs.
Hope this makes sense. Thanks
It looks like you're talking about the keys. In the Firebase example, the keys are things like fred, but in your data they appear as -iKvpJ...
If you insert your records using push, then Firebase automatically assigns the key:
firebase.child('users').push({ name: 'Fred' });
// /users/-KvpJ.../name/Fred
Use child and set to specify your own keys:
firebase.child('users/fred').set({ name: 'Fred' });
// /users/fred/name/Fred
Related
How can I create an array in firestore that can save external links?
I want to save the title and the href so that I can use both values in the read.
I want the links attribute to be an array so that I can save multiple links. Is it possible to do that in a single firebase attribute, or should I create separate link attributes with a href and title for each one (ie firstLinkTitle, firstLinkHref)?
It's not possible to have a number of links, that would be a different array - similar to an array of arrays.
The possibility for the creation of a field of type array for your documents, you can either use the console, where this type is available or via code as the following example:
const data = {
stringExample: 'Example',
arrayExample: ['Title', 'href']
};
const res = await db.collection('data').doc('one').set(data);
With the above example, you should be able to create a field of type array and set the data to it.
Besides that, if you want to update data from your array without uploading all the data again, you can use the function arrayUnion() or use the arrayRemove(), to remove elements from it.
You can get more information on how to work with arrays in Firestore, by checking the below documentation.
Add Data
In case you need something like nested arrays, indeed, you will need to have a "child" collection that will be linked to the father one.
Let me know if the information helped you!
I have a general MongoDB question as I have recently found an issue with how I store things.
Currently, there is a collection called spaces like this:
{
_id: 5e1c4689429a8a0decf16f69,
challengers: [
5dfa24dce9cbc0180fb60226,
5dfa26f46719311869ac1756,
5dfa270c6719311869ac1757
],
tasks: [],
owner: 5dfa24dce9cbc0180fb60226,
name: 'testSpace',
description: 'testSpace'
}
As you can see, this has a challengers array, in which we store the ID of the User.
Would it be okey, if instead of storing the ID, I would store the entire User object, minus fields such as password etc?
Or should I continue with this reference path of referring to the ID of other documents?
The problem I have with this, is that when I want to go through all the spaces that a user has, I want to see what members are a part of that space (challengers array). However, I receive the IDS instead of name and email obviously. I am therefore struggling with sending the correct data to the frontend (I have tried doing some manual manipulation without luck).
So, if I have to continue the path of reference, then I will need to solve my problem somehow.
If it is okey to store the entire object in the array, It would be a lot easier.
HOWEVER, I want to do what is the best practice.
Thank you everyone!
I am struggling to overcome to issue I have. I am trying to delete a parent node/key given I find the correct child value.
My database is structure liked this
I am querying my database by a certain value, objectID, as it will match the postID which is passed through the parameters. The objectID value is removed. However, I am struggling to remove the key in which it falls under.
I have had mixed results so far:
I can either remove the objectID value using this code:
refSnap?.ref.child("objectID").child(postID).removeValue()
Of I can remove the whole notifications node/directory, using this:
refSnap?.ref.child("objectID").queryEqual(toValue: postID).ref.removeValue()
refSnap?.key gives me all the keys/nodes under the notifications node.
I cannot access the key which the objectID and all other information is stored under as it is .childByAutoId. Can anyone possibly help me as to how I can sort this issue?
While the other answer provides some insight with an alternate and workable structure, the ability to delete a node based on a child is fairly straightforward and directly addresses the question without changing the structure.
(note that the structure may need to be changed anyway but for this exercise, we'll use it as is.)
Given a structure suggested in the question:
notification
"rtupy..." //childByAutoId
"-LFEMjAcny..." // childByAutoId
"-LFEzrrq..." // childByAutoId
from: "aw,sdasdad"
objectID: "-LFEMjAcn...."
timestamp: 15292
type: "comment"
Suppose you want to delete the node "-LFEzrrq..." as shown in your screenshot. That node contains the child objectID: "-LFEMjAcn...."
To delete the node you need query for the node that contains the objectID you want which, according to the question, is working and returning the correct child.
Use the returned snapshot to obtain it's parent key, and get the path to that node and delete it. Note that we don't know what process or code the OP used to obtain the node they want to delete - perhaps it was from another query and the node reference was passed in or some other means.
let queryRef = //unknown how, but build the query for objectID = "-LFEMjAcny...."
queryRef.observeSingleEvent(of: .value, with: { snapshot in
let key = snapshot.key //this is the parent key of the objectID node i.e. -LFEMzrrq..."
let parentRef = snapshot.ref.parent! //this is the path to that parent
let refToDelete = parentRef.child(key) //add the parent key to the path: -LFEzrrq
refToDelete.removeValue() //delete it
})
As you can see, regardless of the parent nodes' key, or how deep it is, this code will delete the node found in the query.
The key names do not matter so using .childByAutoId as references to tie your nodes together is safe and generally best practice as disassociating node keys from the data they contain makes your structure highly expandable.
Your issue is that you are using childByAutoId and you can't "tie" these random alphanumerics to something(in this case the post).
The structure that i would set is this:
-notifications
--uid //notifications for user
--- userAid+userBid //follow notification, if they unfollow you already now which one it is and you can go and delete it
---commentNotificationID // you give this notification the same Id that the comment has, so if the user deletes the comment you use that id to delete the notification as well.
I am pretty new to both Swift and Firebase, and I am attempting to make a simple app using Firebase as the backend. As far as I know, there is no memory-efficient way to use the numChildren() function without loading every single child into memory for counting, so I am implementing my own simple counter for the number of "Events" that have been created in my app.
The documentation for Firebase states that the childByAutoID() method should be used for updating lists in multi-user applications. I am assuming it adds a timestamp to the requested update and does them in order.
My question is whether it is necessary to use childByAutoID() when only updating a SINGLE field in a multi-user application. That is, will there be conflicts on my numEvents field if I do:
dbRef = FIRDatabase.database().reference()
dbRef.child("numEvents").setValue(num)
Or must I do:
dbRef = FIRDatabase.database().reference()
dbRef.child("numEvents").childByAutoId().setValue(num)
In order to avoid write conflicts? My only real confusion is that the documentation for childByAutoID stresses that it is useful when the children are a list of items, but mine is only a single item.
If you are only updating a single field you should not be using childByAutoId. To update a child value for an object, you need to obtain a reference to that object somehow, perhaps by a query of some sort (in many cases you will naturally already have a reference to the object if it needs to be changed) and you can change the value like this:
dbRef.child("events").child(objectToUpdateId).child(fieldToUpdateKey).setValue(newValue)
childByAutoId in this context would be used to create a new field like:
dbRef.child("events").childByAutoId().setValue(newObject)
I'm not exactly sure how this applies to your situation, but those are some descriptions of how to update a field, and use childByAutoId.
What childByAutoId does is create a unique key for a node, to avoid using the same key multiple times and then creating data conflicts like inconsistency (not write conflicts) to avoid write conflicts you use the transaction blocks.
The best way to learn is to try it out
If num == 1 , in the first example the result will be
dbRef:{
numEvents:1
}
While the second will be
dbRef:{
numEvents:{
//The auto-generated key
KLBHJBjhbjJBJHB:1
}
}
The childByAutoId would be useful if you want to save in a node multiple children of the same type, that way each children will have its own unique identifier
For example
pet:{
KJHBJJHB:{
name:fluffy,
owner:John Smith,
},
KhBHJBJjJ:{
name:fluffy,
owner:Jane Foster,
}
}
This way you have a unique identifier for cases where there is no clear way with the item data to guarantee it will be unique (in this case the pet's name)
Few things here:
childByAutoId is not a timestamp. But is used to create unique nodes in any given node.
Use case of childByAutoId :
You have messages node which stores messages from multiple user who are involved in a group chat. So each user can add messages in the group chat so you would do something like this each time user sends message:
dbRef = FIRDatabase.database().reference()
dbRef.child("messages").childByAutoId().setValue(messageText)
So this will create a unique message id for each message from different users. This will kind of act like primary key of message in normal databases.
The structure of database will be something like this:
messages: {
"randomIdGenerated-12asd12" : "hello",
"randomIdGenerated-12323D123" : "Hi, HOw are you",
}
So in your case your first approach is good enough! Since you dont need unique node for counting number of events added.
I need numeric IDs for human readability. How do I get it in Firebase?
I want numeric ID for keys, e.g. "000000001", "000000002","00000003","00000004".
The reason I need it is because these IDs will become the permanent object ID both online and offline. I want users to be able to browse that object page by just entering URL "/objects/00000001" without efforts.
I am asking here, because I want to know if this can be done without using .priority, sub-properties, etc. I guess set method can do it somehow. If it is not possible, just tell me no, I can accept that answer.
I'd suggest reading through the Firebase documentation. Specifically, see the Saving Data portion of the Firebase JavaScript Web Guide.
From the guide:
Getting the Unique ID Generated by push()
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({
author: "gracehop",
title: "Announcing COBOL, a New Programming Language"
});
// Get the unique ID generated by push() by accessing its key
var postID = newPostRef.key;
Source: https://firebase.google.com/docs/database/admin/save-data#section-ways-to-save
A push generates a new data path, with a server timestamp as its key. These keys look like -JiGh_31GA20JabpZBfa, so not numeric.
If you wanted to make a numeric only ID, you would make that a parameter of the object to avoid overwriting the generated key.
The keys (the paths of the new data) are guaranteed to be unique, so there's no point in overwriting them with a numeric key.
You can instead set the numeric ID as a child of the object.
You can then query objects by that ID child using Firebase Queries.
From the guide:
In JavaScript, the pattern of calling push() and then immediately calling set() is so common that we let you combine them by just passing the data to be set directly to push() as follows. Both of the following write operations will result in the same data being saved to Firebase:
// These two methods are equivalent:
postsRef.push().set({
author: "gracehop",
title: "Announcing COBOL, a New Programming Language"
});
postsRef.push({
author: "gracehop",
title: "Announcing COBOL, a New Programming Language"
});
Source: https://firebase.google.com/docs/database/admin/save-data#getting-the-unique-key-generated-by-push
As explained above, you can use the Firebase default push id.
If you want something numeric you can do something based on the timestamp to avoid collisions
f.e. something based on date,hour,second,ms, and some random int at the end
01612061353136799031
Which translates to:
016-12-06 13:53:13:679 9031
It all depends on the precision you need (social security numbers do the same with some random characters at the end of the date). Like how many transactions will be expected during the day, hour or second. You may want to lower precision to favor ease of typing.
You can also do a transaction that increments the number id, and on success you will have a unique consecutive number for that user. These can be done on the client or server side.
(https://firebase.google.com/docs/database/android/read-and-write)
Adding to the #htafoya answer.
The code snippet will be
const getTimeEpoch = () => {
return new Date().getTime().toString();
}
As the docs say, this can be achieved just by using set instead if push.
As the docs say, it is not recommended (due to possible overwrite by other user at the "same" time).
But in some cases it's helpful to have control over the feed's content including keys.
As an example of webapp in js, 193 being your id generated elsewhere, simply:
firebase.initializeApp(firebaseConfig);
var data={
"name":"Prague"
};
firebase.database().ref().child('areas').child("193").set(data);
This will overwrite any area labeled 193 or create one if it's not existing yet.
https://firebase.google.com/docs/firestore/manage-data/transactions
Use transactions and keep a number in the database somewhere that you can increase by one. This way you can get a nice numeric and simple id.