Firebase remove() entire nested array in database

Question

How does one delete an entire nested child from a Firebase database by referencing an entry to find the desired point of deletion?

For example, I have two entries nested under (list). (1) -KcxacywN4EkvwAzugfV and (2) -KcxaeBAIW-WgLAsajvV. I want to remove (2) -KcxaeBAIW-WgLAsajvV from the database using it's ID -KcxaeBAIW-WgLAsajvU-4-725391765511696 (See picture below).

I have a button setup for each database entry, to display a remove button. Each button, contains the data- or ID for each database entry.

rootRef.on("child_added", snap => {
    var title = snap.child("title").val();
    var link = snap.child("link").val();
    var type = snap.child("type").val();
    var id = snap.child("id").val();
      $("#table_data").append("<div class='col-lg-4'><div class='card card-app'><div class='card-block'><h4 class='card-title'>"+ title +"</h4><small>"+ type +"</small><hr><a href='"+ link +"' target='_blank'>Download</a>           <a class='user float-right' onclick='removeClick()' data-name='"+ id +"'>Remove</a>            </div></div></div>");
  });

The onClick event and associated id for the button, trigger this function. My mental idea, is to then take the ID from data- to delete its nested child, (2) -KcxaeBAIW-WgLAsajvV from the database. Same process for all other nested entries.

function removeClick() {
  $(".user").click(function() {
        rvm = $(this).attr("data-name");
    });
  alert(rvm);
  firebaseRef.remove(rvm);
}

I've studied https://firebase.google.com/docs/database/web/read-and-write and can't seem to figure out the actual deletion of the nested entry. How can I use remove() or maybe another method to accomplish this?

I have been trying this, to get a better understanding.

firebaseRef.child(rvm).remove();

Since rootRef, is how I'm viewing data. I tried.

rootRef.child().remove();

This simply deletes the whole database...

Final running code:

function removeClick() {
  $(".user").click(function() {
        rvm = $(this).attr("data-name");
  });
  alert(rvm);
  var query = rootRef.orderByChild("id").equalTo(rvm);
  query.once("value", function(snapshot) {
   snapshot.forEach(function(itemSnapshot) {
       itemSnapshot.ref.remove();
   });
 });
}

Frank van Puffelen · Accepted Answer · 2017-02-14 17:55:57Z

3

You can only remove an item if you know its key. So given your current structure, you will first need to look up the key for the id you mention.

Assuming you have a variable ref that points to the root of the database:

var listRef = ref.child("list");
var query = listRef.orderByChild("id").equalTo("-KcxaeBAIW-WgLAsajvU-4-725391765511696");
query.once("value", function(snapshot) {
   snapshot.forEach(function(itemSnapshot) {
       itemSnapshot.ref.remove();
   }); 
});

If you have only a single child with the id, you should consider restructuring your database to use the id as the key. If you do that, you could remove the item with:

listRef.child("-KcxaeBAIW-WgLAsajvU-4-725391765511696").remove()

answered Feb 14, 2017 at 17:55

Frank van Puffelen

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1 Comment

user5009455 Over a year ago

That worked! Thank you. I see now, you have to equate the reference somehow. I've posted to the question, the working code.

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