通过自动生成的文档ID从Firestore中删除文档

Question

I'm trying to create a Property Rental application on Android using Firebase Firestore. Right now, I'm trying to implement a method to delete a specific document (property) within my collection inside Firestore. I figure it is by referencing the auto-generated ID for that particular document, but I simply couldn't get around it.

This is how the delete feature should work:

1. User clicks on a property item from the RecyclerView
2. It displays a full profile of that property
3. User clicks the delete button from the top right corner and deletes the property from the Firestore database

Here is my code where I'm stucked at:

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    switch(item.getItemId()){
        // The delete button
        case R.id.action_delete_btn:
            // Do this when user clicks on delete button
            Toast.makeText(PropertyProfile.this, "You tried to delete this property", Toast.LENGTH_LONG).show();

            deleteItem(item.getOrder());
            return super.onOptionsItemSelected(item);

        default:
            return false;
    }
}

// Here's my problem
private void deleteItem(int index) {
    firebaseFirestore.collection("Posts")
        .document("[DOCUMENT ID RIGHT HERE!]")
        .delete()
        .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void aVoid) {
                Toast.makeText(PropertyProfile.this, "You successfully deleted this property", Toast.LENGTH_LONG).show();
            }
        });
}

Answer 1

In order to use the document id that you are looking for, first you need to store it in a variable. When you are adding a document to the database and you are using a call to document() method without passing an argument, a unique id is generated. To get that id, you should use the following code:

String documentId = postsRef.document().getId();
yourRef.document(documentId).set(yourModelObject);

In which postsRef is the CollectionReference object of your Posts collection and yourModelObject is the object of your Post class. I also recommend you store that id, as a property of your Post document.

Once you have this id, you can use in your refence like this:

firebaseFirestore
    .collection("Posts")
    .document(documentId)
    .delete().addOnSuccessListener(/* ... */);