delete item out of firebase database - firebase

Question

I have a restaurant bookmarks list in my firebase, but I don't know how to delete a specific restaurant in my database.
So I have the function unfavorite(favorite) where I pass the favorite restaurant as a parameter. Till here, than I want to pass this parameters id to the query to remove from the database like this:
this.afDb.list(`bookmarks/${user.uid}/restaurant/${favorite.restaurant.id})`).remove();
here is a screenshot of my database list:
How can I remove that specific restaurant out of the bookmarks list?

Answer 1

You will first need to add an ".indexOn": ["id"] rule to your database something like this:
"bookmarks": {
"$user_id": {
// normal reads and write rules here
},
".indexOn": ["id"]
This step is necessary for firebase database because otherwise you wont be able to use the orderByChild() and equalTo() methods.
Then, where you have your delete function, you want to instead use:
exampleRef = yourDb.ref("bookmarks/${user.uid}"); //this is just to simplify your reference a bit
exampleRef.orderByChild('id').equalTo(theDeleteIDhere).once('value').then(snapshot => {
snapshot.forEach((restaurant) => {
restaurant.ref.remove();
});
}); //this is a Promise that you can modify to return "true" if successful for example
The example I provided is just the way I have done it before (i.e. I prefer to use promises; hence the then() becuase this makes it easier to return that promise in an angular service which allows me to check whether the request was successful). You can use any variation of this so long as you have the "indexOn" rule and you use any sort of "sorting" method firebase provides here
Method 2
When I wrote this I totally glanced over the ability to map your restaurants like such:
Lets say your project is already listing those restaurants. You can therefore save each restaurant's auto generated id to a variable or map:
restaurants; // this is a map like this <your-identifier:autoID>
you can then easily just call:
exampleRef.child(restaurants[yourIdentifier]).remove();