CODEWITHSUNDEEP
androidfirebasefirebase-realtime-databasekotlin
David
David

Reputation: 23

Firebase Database setValue() and updateChildren() overwrites previous value

I tried to insert new data into a table in Firebase real-time database, but setValue() and updateChildren() both are overwritten previous table and value.

I know that setValue() is replacing previous data, but in my case, updateChildren() is also overwriting previous data.

In the Firebase console, It seems like both methods are delete the previous table and create a new table.

Firebase console when updateChildren() is executed enter image description here

Is my code wrong?

My database structure is:

enter image description here

-accounts
    - $userId
        - missions
            - $productId
                - ...

and Code is:

val missionsReference = FirebaseDatabase.getInstance().getReference("accounts").child(userId).child("missions")
val mission = Mission(product.id, product.imageUrl, product.title, product.logoUrl, remain.timeInMillis, "", -1, snsAddress)
missionsReference.child(product.id).setValue(mission)

val missionValue: Map<String, Any> = mission.toMap()
val missionUpdate: HashMap<String, Any> = HashMap()
missionUpdate[product.id] = missionValue
missionsReference.updateChildren(missionUpdate)
/* I also tried following methods, but it overwrites too.
FirebaseDatabase.getInstance().getReference("accounts/$userId/missions/${product.id}").setValue(mission)
missionsReference.push().setValue(mission)
*/

Upvotes: 0

Views: 1970

Answers (2)

David
David

Reputation: 23

OK, I gave up create missions array in account table. and I tried like, and it works. 😕

FirebaseDatabase.getInstance().reference.child("missions").child(id).setValue(mission)

Still I don't know why this method is works and previous methods are not works. In my opinion, it looks like problem of database level(or depth?)

Screenshot of Firebase console. it works 🤔

Upvotes: 0

Alex Mamo
Alex Mamo

Reputation: 138824

Seeing your database structure and assuming you have to achieve this:

Firebase-root
   |
   --- accounts
         |
         --- userId
               |
               --- missions
                     |
                     --- 0
                     |   |
                     |   --- //Mission details
                     |
                     --- 4
                         |
                         --- //Mission details

Please use the following lines of code:

val missionsReference = FirebaseDatabase.getInstance().reference.child("accounts").child(userId).child("missions")
val mission = Mission(product.id, product.imageUrl, product.title, product.logoUrl, remain.timeInMillis, "", -1, snsAddress)
missionsReference.child("4").setValue(mission)

But instead of passing a hardcoded value to the child() function, I recommend you using the random key are generated by the push() function like this:

missionsReference.push().setValue(mission)

Now, your database structure will look like this:

Firebase-root
   |
   --- accounts
         |
         --- userId
               |
               --- missions
                     |
                     --- randomId
                     |   |
                     |   --- //Mission details
                     |
                     --- randomId
                         |
                         --- //Mission details

Thre is no need to use updateChildren() function in this case. This function is used to update properties under a Mission object, for exmaple if you want to change the `imageUrl`` property.

Upvotes: 2

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