Question

我想申请预订。我需要在其他节点中查找一些数据，然后将其存储在变量中，并在其他节点插入新的数据输入。这是我想要的数据结构：

SELCT 1

例如，我想获取数据描述表格laundry_category节点并将其插入节点洗衣店。可能吗？我在我的代码中尝试它但它不起作用。这是我的addLaundry.java代码：

addLaundry.java

{
"laundry_category" : {
  "laundry_category1" : {
      "name" : "clean laundry",
      "description" : "xxxxxxx"
  }
},

"laundry" : {
  "laundry_category1" : {
      "laundry_id_1" : {
        "name" : "ABC",
        "colour" : "red",
        "description" : "xxxxx"
    }
 }
}

Laundry.java

DatabaseReference databaseLaundry;
DatabaseReference databaseCategory;

List<Laundry> laundryList;

@Override
protected void onStart() {
    super.onStart();

    databaseLaundry.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            laundryList.clear();

            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                Laundry laundry = postSnapshot.getValue(Laundry.class);
                laundryList.add(laundry);
            }



            LaundryList adapter = new LaundryList(TambahLaundryActivity.this, laundryList);
            listViewLaundry.setAdapter(adapter);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_add_laundry);


    btAddLaundry = (Button)findViewById(R.id.bn_add_laundry);
    listViewLaundry = (ListView)findViewById(R.id.listViewLaundryLis);

    laundryList = new ArrayList<>();


    Intent intentAddLaundry = getIntent();

    String id_category = intentAddLaundry.getStringExtra(MainActivity.category_id);
    String description_category = intentTambahLaundry.getStringExtra(MainActivity.category_description);

    databaseLaundry = FirebaseDatabase.getInstance().getReference("laundry").child(id_category);

    databaseLaundry = FirebaseDatabase.getInstance().getReference("laundry").child(description_category);

    btAddLaundry.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            addLaundry();
        }
    });


}

public void addLaundry() {
    databaseLaundry.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                category a = postSnapshot.getValue(category.class);
                String var_category_description = ((Map)a).get("category_description").toString();

                String id = databaseLaundry.push().getKey(); 
                Laundry laundry = new Laundry(id, name_laundry, var_category_description); 
                databaseLaundry.child(id).setValue(laundry); 
            }

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
  }
}

category.java

public class Laundry {
  private String laundry_id;
  private String laundry_nama;
  private String laundry_alamat;
  private String kategori_nama;

public Laundry() {

}

public Laundry(String laundry_id, String laundry_name, String category_description {
    this.laundry_id = laundry_id;
    this.laundry_nama = laundry_nama;
    this.category_description = category_description;
}

public String getLaundry_id() {
    return laundry_id;
}

public String getLaundry_name() {
    return laundry_name;
}

public String getLaundry_alamat() {
    return laundry_alamat;
}

public String getCategory_description() {
    return category_description;
  }
}

非常感谢你的帮助:)）

Answer 1

如果要在多个位置保存相同的数据，在上传数据时，需要在每个async function getMoviesFromApi() { try { let response = await fetch('https://facebook.github.io/react-native/movies.json'); let responseJson = await response.json(); return responseJson.movies; } catch(error) { console.error(error); } }对象上执行相同的操作。所以为了达到这个目的，请使用这两个参考文献：

DatabaseReference

和

DatabaseReference idCateoryRef = FirebaseDatabase.getInstance().getReference("laundry").child(id_category);

代码中的错误是您初始化相同的DatabaseReference descriptionCategoryRef = FirebaseDatabase.getInstance().getReference("laundry").child(description_category);两次。如上所述，您需要为每个操作设置不同的DatabaseReference。

希望它有所帮助。

在firebase数据库中获取一个值并将其保存在变量中：android

1 个答案: