How to delete documents from firebase firestore using where clause inside OnClickListener

Question

i want to check if a document already exists upon an on click listener.

if this document exists already, then it should be deleted and not added again.

i read firebase firestore documentation but they dont give much details about these matters.

so heres what i tried:

this is my onclick listener that will add a document to the database if none exist:

details_fave.setOnClickListener(new View.OnClickListener() {
  @Override
            public void onClick(View view) {
                Map<String,Object> fav = new HashMap<>();

                fav.put("shopID",SID);
                fav.put("usersID",UID);
                fav.put("ShopHeaderImg",sHI);
                fav.put("ShopProfileImg",sPI);
                fav.put("address",sA);
                fav.put("costEst",sCost);
                fav.put("country",sC);
                fav.put("latitude",sLat);
                fav.put("location",sL);
                fav.put("name",sN);
                fav.put("numTables",sNumTable);
                fav.put("ratings",sR);
                fav.put("summary",sSummary);
                fav.put("timing",sT);



                fStore.collection("Favorites").add(fav).addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                    @Override
                    public void onSuccess(DocumentReference documentReference) {
                        Toast.makeText(DetailsActivity.this,"Saved", Toast.LENGTH_SHORT).show();
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(DetailsActivity.this,"Something went wrong", Toast.LENGTH_SHORT).show();
                    }
                });
            }
        });

         

what i wanna do first is to check if the document exists or not, if it exists then delete it, if it doesnt then insert.

this is what i am trying to do to delete a record if found in a where clause:

 Task<QuerySnapshot> ref = fStore.collection("Favorites")
                .whereEqualTo("usersID", UID).whereEqualTo("shopID",SID)
                .get()
                .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<QuerySnapshot> task) {
                        if (task.isSuccessful()) {
                            for (QueryDocumentSnapshot document : task.getResult()) {
                                document.getReference().delete();
                            }
                        } else {
                            Log.d("whatever", "Error getting documents: ", task.getException());
                        }
                    }
                });

but still how would i implement it inside the onclick listener?

how can i do this with firebase firestore?

Answer 1

First of all you should separate your app from the evey logic around accessing your data.

Try using ViewModels for this.

Any way, I would do something like that:

 public void onClick(View view) {
    Map<String,Object> fav = new HashMap<>();

    fav.put("shopID",SID);
    fav.put("usersID",UID);
    fav.put("ShopHeaderImg",sHI);
    fav.put("ShopProfileImg",sPI);
    fav.put("address",sA);
    fav.put("costEst",sCost);
    fav.put("country",sC);
    fav.put("latitude",sLat);
    fav.put("location",sL);
    fav.put("name",sN);
    fav.put("numTables",sNumTable);
    fav.put("ratings",sR);
    fav.put("summary",sSummary);
    fav.put("timing",sT);

    Task<QuerySnapshot> ref = fStore.collection("Favorites")
            .whereEqualTo("usersID", UID).whereEqualTo("shopID",SID)
            .get()
            .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull Task<QuerySnapshot> task) {
                    if (task.isSuccessful()) {
                        //if there is no document to delete the loop will exit without iterating even once
                        for (QueryDocumentSnapshot document : task.getResult()) 
                            document.getReference().delete();
                        //here we stand when we cleared the history of the user favorite list in the specific store, we can enter the new list
                        fStore.collection("Favorites").add(fav).addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                            @Override
                            public void onSuccess(DocumentReference documentReference) {
                                Toast.makeText(DetailsActivity.this,"Saved", Toast.LENGTH_SHORT).show();
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {
                                Toast.makeText(DetailsActivity.this,"Something went wrong", Toast.LENGTH_SHORT).show();
                            }
                        });
                    } else {
                        Log.d("whatever", "Error getting documents: ", task.getException());
                    }
                }
            });

    
}

It's a bit of a mess, but it will get the job done.

If you have similar actions to preform that don't include querying document use TRANSACTIONS