[英]how to delete the auto generated item from push method from Firebase Real-time database
I am new to Firebase and I am facing a problem in delete an item from the recycler view I created.我是 Firebase 的新手,在从我创建的回收站视图中删除项目时遇到了问题。 but I am unable to understand how to delete items using an auto-generated key.
但我无法理解如何使用自动生成的密钥删除项目。 This is how I added item into the database :
这就是我将项目添加到数据库的方式:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("categories");
String key = reference.push().getKey();
reference.child(key).setValue(categoryData).addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if(task.isSuccessful()){
Toast.makeText(add_category.this, "Category added", Toast.LENGTH_SHORT).show();
finish();
}
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(add_category.this, "Failed to add", Toast.LENGTH_SHORT).show();
}
});
As in your comment, if you want to delete, for example, the second item, please use the following lines of code:如您的评论,如果您想删除,例如,第二项,请使用以下代码行:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference secondChildRef = rootRef.child("categories").child("-M1qUEGi0u4rX5Ju59r4");
secondChildRef.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if (task.isSuccessful()) {
Log.d("TAG", "Second item deleted!");
}
}
});
So to delete a particular item, you to know its ID so you can add it to the reference.因此,要删除特定项目,您需要知道其 ID,以便将其添加到引用中。
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