[Android/Firebase] Firebase CRUD

Create

final String uniqueKey = dbRef.push().getKey();
databaseReference.child(tablename).child(uniqueKey).setValue(data)

 

Read

ValueEventListener postListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        // 근본
        // Post post = dataSnapshot.getValue(Post.class);
        // 하위 리스트 가져오기
        for (DataSnapshot dataSnapshot: snapshot.getChildren()) {
          val data = dataSnapshot.getValue(return받을class.class);
          list.add(data);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // Getting Post failed, log a message
        Log.w(TAG, "loadPost:onCancelled", databaseError.toException());
    }
};
databaseReference.addValueEventListener(postListener);

 

Update

databaseReference.child(table name).child(uniqueKey).updateChildren(Map<String, Object>);

 

Delete

databaseReference.child(table name).child(uniqueKey).removeValue()

 

Callback

create, update, delete : 작업이 끝나고 성공 실패여부를 callback으로 받을 수 있다.

.addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void unused) {
                Toast.makeText(UploadNotice.this, "Success", Toast.LENGTH_SHORT).show();
            }
        }).addOnFailureListener(new OnFailureListener(){
            @Override
            public void onFailure(@NonNull Exception e) {
                Toast.makeText(UploadNotice.this, "Something went wrong", Toast.LENGTH_SHORT).show();
            }
        });

delete는 onCompleteListener

.addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        Toast.makeText(UpdateTeacherActivity.this, "Deleted Successful", Toast.LENGTH_SHORT).show();
                    }
                }).addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Toast.makeText(UpdateTeacherActivity.this, "Something went wrong", Toast.LENGTH_SHORT).show();
            }
        });

 

 

 

Ref

• firebase docs