En el artículo anterior, hemos visto cómo agregar datos , leer datos y actualizar datos en Firebase Firestore en Android. Ahora veremos Cómo eliminar estos datos agregados dentro de nuestro Firebase Firestore . Así que avanzaremos hacia la implementación de esta eliminación de datos en Android Firebase.
¿Qué vamos a construir en este artículo?
Agregaremos un botón simple dentro de nuestra pantalla de actualización donde actualizamos nuestros datos y dentro de esa pantalla, agregaremos un nuevo botón para eliminar el curso. Después de eliminar, ese curso se eliminará de nuestra base de datos.
Implementación paso a paso
Paso 1: crear un nuevo botón para eliminar los datos dentro del archivo activity_update_course.xml
Como hemos creado una nueva actividad de curso de actualización en el artículo anterior. Así que simplemente le agregaremos un nuevo botón. Agregue el siguiente fragmento de código al archivo activity_update_course.xml .
XML
<!--Button for deleting our course--> <Button android:id="@+id/idBtnDeleteCourse" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_margin="10dp" android:layout_weight="1" android:text="Delete Course" android:textAllCaps="false" />
A continuación se muestra el código actualizado para el archivo activity_update_course.xml .
XML
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".UpdateCourse"> <!--Edittext for getting course Name--> <EditText android:id="@+id/idEdtCourseName" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginStart="10dp" android:layout_marginTop="20dp" android:layout_marginEnd="10dp" android:hint="Course Name" android:importantForAutofill="no" android:inputType="text" /> <!--Edittext for getting course Duration--> <EditText android:id="@+id/idEdtCourseDuration" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginStart="10dp" android:layout_marginTop="20dp" android:layout_marginEnd="10dp" android:hint="Course Duration in min" android:importantForAutofill="no" android:inputType="time" /> <!--Edittext for getting course Description--> <EditText android:id="@+id/idEdtCourseDescription" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginStart="10dp" android:layout_marginTop="20dp" android:layout_marginEnd="10dp" android:hint="Course Description" android:importantForAutofill="no" android:inputType="text" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:weightSum="2"> <!--Button for updating your course to Firebase--> <Button android:id="@+id/idBtnUpdateCourse" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_margin="10dp" android:layout_weight="1" android:text="Update Course" android:textAllCaps="false" /> <!--Button for deleting our course--> <Button android:id="@+id/idBtnDeleteCourse" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_margin="10dp" android:layout_weight="1" android:text="Delete Course" android:textAllCaps="false" /> </LinearLayout> </LinearLayout>
Paso 2: ahora tenemos que inicializar este botón en el archivo UpdateCourses.java y agregarle onClickListner
Vaya al archivo UpdateCourses.java y agregue el siguiente fragmento de código.
Java
// adding on click listener for delete button
deleteBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// calling method to delete the course.
deleteCourse(courses);
}
});
private void deleteCourse(Courses courses) {
// below line is for getting the collection
// where we are storing our courses.
db.collection("Courses").
// after that we are getting the document
// which we have to delete.
document(courses.getId()).
// after passing the document id we are calling
// delete method to delete this document.
delete().
// after deleting call on complete listener
// method to delete this data.
addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
// inside on complete method we are checking
// if the task is success or not.
if (task.isSuccessful()) {
// this method is called when the task is success
// after deleting we are starting our MainActivity.
Toast.makeText(UpdateCourse.this, "Course has been deleted from Database.", Toast.LENGTH_SHORT).show();
Intent i = new Intent(UpdateCourse.this, MainActivity.class);
startActivity(i);
} else {
// if the delete operation is failed
// we are displaying a toast message.
Toast.makeText(UpdateCourse.this, "Fail to delete the course. ", Toast.LENGTH_SHORT).show();
}
}
});
}
A continuación se muestra el código actualizado para el archivo UpdateCourses.java .
Java
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.firestore.FirebaseFirestore;
public class UpdateCourse extends AppCompatActivity {
// creating variables for our edit text
private EditText courseNameEdt, courseDurationEdt, courseDescriptionEdt;
// creating a strings for storing our values from Edittext fields.
private String courseName, courseDuration, courseDescription;
// creating a variable for firebasefirestore.
private FirebaseFirestore db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update_course);
Courses courses = (Courses) getIntent().getSerializableExtra("course");
// getting our instance from Firebase Firestore.
db = FirebaseFirestore.getInstance();
// initializing our edittext and buttons
courseNameEdt = findViewById(R.id.idEdtCourseName);
courseDescriptionEdt = findViewById(R.id.idEdtCourseDescription);
courseDurationEdt = findViewById(R.id.idEdtCourseDuration);
// creating variable for button
Button updateCOurseBtn = findViewById(R.id.idBtnUpdateCourse);
Button deleteBtn = findViewById(R.id.idBtnDeleteCourse);
courseNameEdt.setText(courses.getCourseName());
courseDescriptionEdt.setText(courses.getCourseDescription());
courseDurationEdt.setText(courses.getCourseDuration());
// adding on click listener for delete button
deleteBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// calling method to delete the course.
deleteCourse(courses);
}
});
updateCOurseBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
courseName = courseNameEdt.getText().toString();
courseDescription = courseDescriptionEdt.getText().toString();
courseDuration = courseDurationEdt.getText().toString();
// validating the text fields if empty or not.
if (TextUtils.isEmpty(courseName)) {
courseNameEdt.setError("Please enter Course Name");
} else if (TextUtils.isEmpty(courseDescription)) {
courseDescriptionEdt.setError("Please enter Course Description");
} else if (TextUtils.isEmpty(courseDuration)) {
courseDurationEdt.setError("Please enter Course Duration");
} else {
// calling a method to update our course.
// we are passing our object class, course name,
// course description and course duration from our edittext field.
updateCourses(courses, courseName, courseDescription, courseDuration);
}
}
});
}
private void deleteCourse(Courses courses) {
// below line is for getting the collection
// where we are storing our courses.
db.collection("Courses").
// after that we are getting the document
// which we have to delete.
document(courses.getId()).
// after passing the document id we are calling
// delete method to delete this document.
delete().
// after deleting call on complete listener
// method to delete this data.
addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
// inside on complete method we are checking
// if the task is success or not.
if (task.isSuccessful()) {
// this method is called when the task is success
// after deleting we are starting our MainActivity.
Toast.makeText(UpdateCourse.this, "Course has been deleted from Database.", Toast.LENGTH_SHORT).show();
Intent i = new Intent(UpdateCourse.this, MainActivity.class);
startActivity(i);
} else {
// if the delete operation is failed
// we are displaying a toast message.
Toast.makeText(UpdateCourse.this, "Fail to delete the course. ", Toast.LENGTH_SHORT).show();
}
}
});
}
private void updateCourses(Courses courses, String courseName, String courseDescription, String courseDuration) {
// inside this method we are passing our updated values
// inside our object class and later on we
// will pass our whole object to firebase Firestore.
Courses updatedCourse = new Courses(courseName, courseDescription, courseDuration);
// after passing data to object class we are
// sending it to firebase with specific document id.
// below line is use to get the collection of our Firebase Firestore.
db.collection("Courses").
// below line is use toset the id of
// document where we have to perform
// update operation.
document(courses.getId()).
// after setting our document id we are
// passing our whole object class to it.
set(updatedCourse).
// after passing our object class we are
// calling a method for on success listener.
addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
// on successful completion of this process
// we are displaying the toast message.
Toast.makeText(UpdateCourse.this, "Course has been updated..", Toast.LENGTH_SHORT).show();
}
}).addOnFailureListener(new OnFailureListener() {
// inside on failure method we are
// displaying a failure message.
@Override
public void onFailure(@NonNull Exception e) {
Toast.makeText(UpdateCourse.this, "Fail to update the data..", Toast.LENGTH_SHORT).show();
}
});
}
}
Producción:
La estructura final del archivo del proyecto
A continuación se muestra la estructura de archivos para archivos Java:
A continuación se muestra la estructura de archivos para archivos XML:
Publicación traducida automáticamente
Artículo escrito por chaitanyamunje y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA