फ़ायरबेस डेटाबेस से डेटा कैसे पुनर्प्राप्त करें जिसमें नेस्टेड सरणी और ऑब्जेक्ट संरचना है?

Question

मैंने कई स्थानों से डेटा निष्कर्षण कोड की कोशिश की लेकिन हर जगह मुझे एक साधारण सूची में डेटा पुनर्प्राप्त करने का तरीका मिलता है। चूंकि मेरे JSON की संरचना जटिल है और मैं इसे अभी नहीं बदल सकता, इसलिए कृपया फ़ायरबेस डेटाबेस से डेटा पुनर्प्राप्त करने में मेरी सहायता करें। कृपया मदद करें क्योंकि मैं फ़ायरबेस कोड को समझने में सक्षम नहीं हूं। बाद मेरी कोड और JSON डेटाबेस है:

CategoryModel.xml

package com.example.firedb; 

import android.os.Parcel; 
import android.os.Parcelable; 

import java.util.ArrayList; 

/** 
* Created by Android on 5/31/2017. 
*/ 

public class CategoryModel { 

    private ArrayList<CategoryList> categoryList; 

    public CategoryModel() { 
    } 

    public CategoryModel(ArrayList<CategoryList> categoryList) { 
     this.categoryList = categoryList; 
    } 

    public ArrayList<CategoryList> getCategoryList() { 
     return categoryList; 
    } 

    public void setCategoryList(ArrayList<CategoryList> categoryList) { 
     this.categoryList = categoryList; 
    } 


    // CategoryList 

    public static class CategoryList { 

     public int Category_id; 
     public String Category_name; 
     public ArrayList<String>Emails; 
     public ArrayList<String>Epabx; 
     public ArrayList<String>Category_Fax; 
     public ArrayList<Persons> persons; 

     public CategoryList() { 
     } 
     //constructor of CategoryList 

     public CategoryList(int category_id, String category_name, 
          ArrayList<String> emails, ArrayList<String> epabx, ArrayList<String> category_Fax, 
          ArrayList<Persons> persons) { 
      Category_id = category_id; 
      Category_name = category_name; 
      Emails = emails; 
      Epabx = epabx; 
      Category_Fax = category_Fax; 
      this.persons = persons; 
     } 

     // getters and setters of CategoryList 

     public int getCategory_id() { 
      return Category_id; 
     } 

     public void setCategory_id(int category_id) { 
      Category_id = category_id; 
     } 

     public String getCategory_name() { 
      return Category_name; 
     } 

     public void setCategory_name(String category_name) { 
      Category_name = category_name; 
     } 

     public ArrayList<String> getEmails() { 
      return Emails; 
     } 

     public void setEmails(ArrayList<String> emails) { 
      Emails = emails; 
     } 

     public ArrayList<String> getEpabx() { 
      return Epabx; 
     } 

     public void setEpabx(ArrayList<String> epabx) { 
      Epabx = epabx; 
     } 

     public ArrayList<String> getCategory_Fax() { 
      return Category_Fax; 
     } 

     public void setCategory_Fax(ArrayList<String> category_Fax) { 
      Category_Fax = category_Fax; 
     } 

     public ArrayList<Persons> getPersons() { 
      return persons; 
     } 

     public void setPersons(ArrayList<Persons> persons) { 
      this.persons = persons; 
     } 


    } 

    //Persons 

    public static class Persons { 

     private int Person_ID; 
     private String Name; 
     private String Designation; 
     private ArrayList<String> Office_Phone; 
     private ArrayList<String> Residence_Phone; 
     private String VOIP; 
     private String Address; 
     private ArrayList<String>Fax; 
     private String Ext; 
     private ArrayList<String>Extra_info; 
     private String Category_name; 

     public Persons() { 
     } 

     // Constructor of Persons 
     public Persons(int person_ID, String name, String designation, ArrayList<String> office_Phone, 
         ArrayList<String> residence_Phone, String VOIP, String address, ArrayList<String> fax, String ext, 
         ArrayList<String>extra_info, String category_name) { 
      Person_ID = person_ID; 
      Name = name; 
      Designation = designation; 
      Office_Phone = office_Phone; 
      Residence_Phone = residence_Phone; 
      this.VOIP = VOIP; 
      Address = address; 
      Fax = fax; 
      Ext = ext; 
      Extra_info=extra_info; 
      Category_name=category_name; 
     } 

     // Getter and Setters of Persons 

     public int getPerson_ID() { 
      return Person_ID; 
     } 

     public void setPerson_ID(int person_ID) { 
      Person_ID = person_ID; 
     } 

     public String getName() { 
      return Name; 
     } 

     public void setName(String name) { 
      Name = name; 
     } 

     public String getDesignation() { 
      return Designation; 
     } 

     public void setDesignation(String designation) { 
      Designation = designation; 
     } 

     public ArrayList<String> getOffice_Phone() { 
      return Office_Phone; 
     } 

     public void setOffice_Phone(ArrayList<String> office_Phone) { 
      Office_Phone = office_Phone; 
     } 

     public ArrayList<String> getResidence_Phone() { 
      return Residence_Phone; 
     } 

     public void setResidence_Phone(ArrayList<String> residence_Phone) { 
      Residence_Phone = residence_Phone; 
     } 

     public String getVOIP() { 
      return VOIP; 
     } 

     public void setVOIP(String VOIP) { 
      this.VOIP = VOIP; 
     } 

     public String getAddress() { 
      return Address; 
     } 

     public void setAddress(String address) { 
      Address = address; 
     } 

     public ArrayList<String> getFax() { 
      return Fax; 
     } 

     public void setFax(ArrayList<String> fax) { 
      Fax = fax; 
     } 

     public String getExt() { 
      return Ext; 
     } 

     public void setExt(String ext) { 
      Ext = ext; 
     } 

     public ArrayList<String> getExtra_info() { 
      return Extra_info; 
     } 

     public void setExtra_info(ArrayList<String> extra_info) { 
      Extra_info = extra_info; 
     } 

     public String getCategory_name() { 
      return Category_name; 
     } 

     public void setCategory_name(String category_name) { 
      Category_name = category_name; 
     } 

    } 

} 

CardviewActivity:इससे पहले मैं एक परिसंपत्ति फ़ाइल का उपयोग किया है, लेकिन अब मैं firebase जिसका कोड है से डेटा प्राप्त करना चाहते हैं संदिग्ध ऑनलाइन

package com.example.firedb; 

import android.content.Intent; 
import android.graphics.Color; 
import android.graphics.drawable.Drawable; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.support.v7.widget.Toolbar; 
import android.text.Editable; 
import android.text.LoginFilter; 
import android.text.TextWatcher; 
import android.util.Log; 
import android.view.Gravity; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageView; 
import android.widget.LinearLayout; 
import android.widget.RelativeLayout; 
import android.widget.TextView; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.IOException; 
import java.io.InputStream; 
import java.util.ArrayList; 

import static android.R.attr.button; 


public class CardViewActivity extends AppCompatActivity { 
    Toolbar mActionBarToolbar; 
    private RecyclerView mainRecyclerView; 
    private RecyclerView.Adapter mainAdapter; 
    private RecyclerView.LayoutManager mainLayoutManager; 
    private static String LOG_TAG = "CardViewActivity"; 
    EditText inputSearchMain; 
    private ArrayList<CategoryModel.CategoryList> categoryLists; 
    TextView toolbar_title_main; 
    ImageView back_cardviewActivity; 
// DatabaseHandler db; 

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

//   db = new DatabaseHandler (CardViewActivity.this); 

     mActionBarToolbar = (Toolbar) findViewById(R.id.tool_bar); 
     toolbar_title_main=(TextView)findViewById(R.id.toolbar_title); 


//  mActionBarToolbar.setTitle("Hry. Govt. Telephone Directory"); 
     // mActionBarToolbar.setLogo(R.drawable.logotoolbar); 

//  mActionBarToolbar.setTitleMargin(5,2,2,2); 
     setSupportActionBar(mActionBarToolbar); 
     getSupportActionBar().setDisplayShowTitleEnabled(false); 
     toolbar_title_main.setText("Hry. Govt. Telephone Directory"); 
     back_cardviewActivity=(ImageView)findViewById(R.id.back); 
     back_cardviewActivity.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       onBackPressed(); 
      } 
     }); 

     categoryLists=new ArrayList<CategoryModel.CategoryList>(); 
     categoryLists.addAll(getmcategoryset()); 
     mainRecyclerView=(RecyclerView)findViewById(R.id.recyclerView_Main); 
     mainRecyclerView.setHasFixedSize(true); 
     mainLayoutManager=new LinearLayoutManager(this); 
     mainRecyclerView.setLayoutManager(mainLayoutManager); 
//  Log.d("onCreate: ", "List Size: "+categoryLists.size()); 
     mainAdapter=new RecyclerViewAdapterMain(getmcategoryset()); 
     mainRecyclerView.setAdapter(mainAdapter); 
     inputSearchMain = (EditText) findViewById(R.id.inputSearchMain); 

     addTextListener(); 
    } 

    public void addTextListener(){ 

     inputSearchMain.addTextChangedListener(new TextWatcher() { 

      public void afterTextChanged(Editable s) {} 

      public void beforeTextChanged(CharSequence s, int start, int count, int after) {} 

      public void onTextChanged(CharSequence query, int start, int before, int count) { 

       query = query.toString().toLowerCase(); 

       final ArrayList<CategoryModel.CategoryList> filteredList = new ArrayList<CategoryModel.CategoryList>(); 

       for (int i = 0; i < categoryLists.size(); i++) { 

        final String text = categoryLists.get(i).getCategory_name().toLowerCase(); 
        if (text.contains(query)) { 

         filteredList.add(categoryLists.get(i)); 
        } 
       } 

       mainRecyclerView.setLayoutManager(new LinearLayoutManager(CardViewActivity.this)); 
       mainAdapter = new RecyclerViewAdapterMain(filteredList); 
       mainRecyclerView.setAdapter(mainAdapter); 
       mainAdapter.notifyDataSetChanged(); // data set changed 
      } 
     }); 
    } 

    private ArrayList<CategoryModel.CategoryList> getmcategoryset() { 
//  JSONObject obj = new JSONObject(readJSONFromAsset()); 

     try { 

      ArrayList<CategoryModel.CategoryList>categoryList = new ArrayList<CategoryModel.CategoryList>(); 
      JSONObject jsonObject = new JSONObject(readJSONFromAsset()); 

      JSONArray categoryArray = jsonObject.getJSONArray("Category"); 
      Log.d("getmcategoryset", "category count: "+categoryArray.length()); 
      for (int i = 0; i < categoryArray.length(); i++) 
      { 
       JSONObject job = categoryArray.getJSONObject(i); 

       int categoryId = job.getInt("Category_id"); 
       String categoryName = job.getString("Category_name"); 

       //this is for email array 
       ArrayList<String> emails = new ArrayList<>(); 
       JSONArray emailArray = job.getJSONArray("Emails"); 
       for (int j = 0; j< emailArray.length(); j++){ 
//     JSONObject jobE = emailArray.getString(j); 
        emails.add(emailArray.getString(j)); 
       } 

       //This i for Epabx array 
       ArrayList<String> epabx = new ArrayList<>(); 
       JSONArray epabxArray = job.getJSONArray("Epabx"); 
       for (int j = 0; j < epabxArray.length(); j++){ 
//     JSONObject jobE = epabxArray.getString(j); 
        epabx.add(epabxArray.getString(j)); 
       } 

       //This i for Category_Fax array 
       ArrayList<String> category_Fax = new ArrayList<>(); 
       JSONArray category_FaxJson = job.getJSONArray("Category_Fax"); 
       for (int j = 0; j < category_FaxJson.length(); j++){ 
//     JSONObject jobE = category_FaxJson.getString(j); 
        category_Fax.add(category_FaxJson.getString(j)); 
       } 

       //This i for Persons array 
       ArrayList<CategoryModel.Persons> personsList = new ArrayList<>(); 
       JSONArray personsArray = job.getJSONArray("Persons"); 
       for (int j = 0; j < personsArray.length(); j++){ 
        JSONObject jobIn = personsArray.getJSONObject(j); 

        int Person_ID = jobIn.getInt("Person_ID"); 
        String Name = jobIn.getString("Name"); 
        String Designation = jobIn.getString("Designation"); 

        //this is for Office_Phone array 
        ArrayList<String>Office_Phone = new ArrayList<>(); 
        JSONArray office_Phone = jobIn.getJSONArray("Office_Phone"); 
        for (int k=0; k < office_Phone.length(); k++) 
        { 
         Office_Phone.add(office_Phone.getString(k)); 
        } 

        //this is for Residence_Phone array 
        ArrayList<String>Residence_Phone = new ArrayList<>(); 
        JSONArray residence_Phone = jobIn.getJSONArray("Residence_Phone"); 
        for (int k=0; k < residence_Phone.length(); k++) 
        { 
         Residence_Phone.add(residence_Phone.getString(k)); 
        } 

        String VOIP = jobIn.getString("VOIP"); 
        String Address = jobIn.getString("Address"); 


        //this is for Fax array 
        ArrayList<String>Fax = new ArrayList<>(); 
        JSONArray fax = jobIn.getJSONArray("Fax"); 
        for (int k=0; k < fax.length(); k++) 
        { 
         Fax.add(fax.getString(k)); 
        } 

        String Ext = jobIn.getString("Ext"); 

        //this is for Extra_info array 
        ArrayList<String>Extra_info = new ArrayList<>(); 
        JSONArray extra_info = jobIn.getJSONArray("Extra_info"); 
        for (int k=0; k < extra_info.length(); k++) 
        { 
         Extra_info.add(extra_info.getString(k)); 
        } 

        personsList.add(new CategoryModel.Persons(Person_ID, Name, Designation, Office_Phone, Residence_Phone, 
          VOIP, Address, Fax, Ext,Extra_info,categoryName)); 
//     db.addPerson(new CategoryModel.Persons(Person_ID, Name, Designation, Office_Phone, Residence_Phone, 
//       VOIP, Address, Fax, Ext,Extra_info)); 
       } 

       //here your Category[] value store in categoryArrayList 
       categoryList.add(new CategoryModel.CategoryList(categoryId, categoryName, emails, epabx, category_Fax, personsList)); 

//    db.addCategory(new CategoryModel.CategoryList(categoryId, categoryName, emails, epabx, category_Fax, personsList)); 

       Log.i("categoryList size = ", ""+categoryArray.length()); 
       Log.i("cat_name=",""+categoryName); 
      } 

      if (categoryList != null) 
      { 
       Log.i("categoryList size = ", ""+categoryArray.length()); 
      } 
      return categoryList; 
     } catch (JSONException e) { 
      e.printStackTrace(); 
      return null; 
     } 

    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
//  ((RecyclerViewAdapterMain) mainAdapter).setOnItemClickListener(new RecyclerViewAdapterMain() 
//    .CategoryClickListener() { 
//   public void onItemClick(int position, View v) { 
//    Log.i(LOG_TAG, " Clicked on Item " + position); 
//   } 
//  }); 
    } 


} 

RecyclerViewAdapter:

package com.example.firedb; 

import android.content.Context; 
import android.content.Intent; 
import android.os.Bundle; 
import android.support.v7.widget.RecyclerView; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

import java.util.ArrayList; 
import java.util.Arrays; 


public class RecyclerViewAdapterMain extends RecyclerView.Adapter<RecyclerViewAdapterMain.CategoryObjectHolder> { 
    private static String LOG_TAG = "categoryRecyclrVwAdptr"; 
    private ArrayList<CategoryModel.CategoryList> mcategoryset; 
    private static CategoryClickListener categoryClickListener; 

    public static class CategoryObjectHolder extends RecyclerView.ViewHolder { 
     TextView category_name; 
     /*TextView category_emails; 
     TextView category_epabx; 
     TextView category_fax;*/ 

     public CategoryObjectHolder(View itemView){ 
      super(itemView); 
      category_name=(TextView)itemView.findViewById(R.id.category_name); 
      /*category_emails=(TextView)itemView.findViewById(R.id.category_emails); 
      category_epabx=(TextView)itemView.findViewById(R.id.category_epabx); 
      category_fax=(TextView)itemView.findViewById(R.id.category_fax);*/ 
      Log.i(LOG_TAG, "Adding Listener"); 

     } 
//  @Override 
//  public void onClick(View v) { 
//   categoryClickListener.onItemClick(getAdapterPosition(), v); 
//  } 
    } 
// public void setOnItemClickListener(CategoryClickListener categoryClickListener) { 
//  this.categoryClickListener = categoryClickListener; 
// } 

    public RecyclerViewAdapterMain(ArrayList<CategoryModel.CategoryList> myDataset) { 
     mcategoryset = myDataset; 
    } 

    public CategoryObjectHolder onCreateViewHolder(ViewGroup parent,int viewType){ 
     View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.card_view_row_main_activity,parent,false); 
     CategoryObjectHolder categoryObjectHolder=new CategoryObjectHolder(view); 
     return categoryObjectHolder; 
    } 

    @Override 
    public void onBindViewHolder(CategoryObjectHolder holder, final int position) { 
     /*final StringBuilder stringBuilder_emails = new StringBuilder(); 
     for (String email : mcategoryset.get(position).getEmails()) { 
      if (!stringBuilder_emails.toString().isEmpty()) { 
       stringBuilder_emails.append(", "); 
      } 
      stringBuilder_emails.append(email); 
     } 

     final StringBuilder stringBuilder_Epabx = new StringBuilder(); 
     for (String epabx : mcategoryset.get(position).getEpabx()) { 
      if (!stringBuilder_Epabx.toString().isEmpty()) { 
       stringBuilder_Epabx.append(", "); 
      } 
      stringBuilder_Epabx.append(epabx); 
     } 

     final StringBuilder stringBuilder_Category_Fax = new StringBuilder(); 
     for (String category_Fax : mcategoryset.get(position).getCategory_Fax()) { 
      if (!stringBuilder_Category_Fax.toString().isEmpty()) { 
       stringBuilder_Category_Fax.append(", "); 
      } 
      stringBuilder_Category_Fax.append(category_Fax); 
     }*/ 

     holder.category_name.setText(mcategoryset.get(position).getCategory_name()); 
     /*holder.category_emails.setText(stringBuilder_emails.toString()); 
     holder.category_epabx.setText(stringBuilder_Epabx.toString()); 
     holder.category_fax.setText(stringBuilder_Category_Fax.toString());*/ 
     holder.itemView.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       Intent i = new Intent (v.getContext(), PeopleListActivity.class); 
       i.putParcelableArrayListExtra("Persons",mcategoryset.get(position).getPersons()); 
       i.putStringArrayListExtra("emails",mcategoryset.get(position).getEmails()); 
       //i.putExtras(b); 
       v.getContext().startActivity(i); 

      } 
     }); 
    } 
    public void addItem(CategoryModel.CategoryList dataObj, int index) { 
     mcategoryset.add(index, dataObj); 
     notifyItemInserted(index); 
    } 

    public void deleteItem(int index) { 
     mcategoryset.remove(index); 
     notifyItemRemoved(index); 
    } 

    @Override 
    public int getItemCount() { 
     return mcategoryset.size(); 
    } 

    public interface CategoryClickListener { 
     public void onItemClick(int position, View v); 
    } 
} 

Answer 1

एक ही रास्ता है कि यह एक ValueEventListener उपयोग कर रहा है Firebase डेटाबेस से डेटा प्राप्त करने। फायरबेस, एसिंक्रोनस कॉल के साथ काम करता है, इसलिए आप फ़ंक्शन को कॉल नहीं कर सकते हैं, डेटा प्राप्त कर सकते हैं और इसका उपयोग कर सकते हैं। आपको एक विशिष्ट डेटाबेस संदर्भ में ValueEventListener सेट करना होगा।

आपकी वास्तविक समस्या के लिए, आपको एक सरणी बनाना है, फायरबेस संदर्भ सेट करना है, ValueEventListener जोड़ें और सरणी में श्रेणीसूची की प्रत्येक घटना को अंदर जोड़ें। अंत में, अभी भी ValueEventListener के अंदर, आप अपने CategoryModel, पैरामीटर के रूप में CategoryList की सरणी के साथ अपने यूआई, CategoryModel में डेटा देखने के बना सकते हैं और अद्यतन: के लिए यह काम कर रहे है

CategoryModel categoryModel; 
ArrayList<CategoryList> array = new ArrayList<>(); 
FirebaseDatabase database = FirebaseDatabase.getInstance(); 
DatabaseReference categoryRef = database.getReference("Category"); 
categoryRef.addValueEventListener(new ValueEventListener() { 
    @Override 
    public void onDataChange(DataSnapshot dataSnapshot) { 
     // This method is called once with the initial value and again 
     // whenever data at this location is updated. 
     for (DataSnapshot childSnapshot: dataSnapshot.getChildren()) { 
      CategoryList categoryList = childSnapshot.getValue(CategoryList.class); 
      array.add(categoryList); 
     } 
     categoryModel = new CategoryModel(array); 
     // Method to show the data in category model, 
     // usually populating an ListView or something 
     updateUI() 
    } 

    @Override 
    public void onCancelled(DatabaseError error) { 
     // Failed to read value 
     Log.w(TAG, "Failed to read value.", error.toException()); 
    } 
}); 

, अपने CategoryList वर्ग के लिए है अपने सदस्यों के सभी सेटर्स को लागू करें ताकि "datasnapshot.getValue()" काम करता है। एक और दृष्टिकोण, हो सकता है CategoryList में एक निर्माता कि इस तरह से एक DataSnapshot recibe बनाएँ:

public CategoryList(DataSnapshot snapshot){ 
    Category_id = snapshot.child("Category_id").getValue(int.class); 
    Category_name = snapshot.child("Category_name").getValue(String.class); 
    GenericTypeIndicator<List<String>> stringList = new GenericTypeIndicator<List<String>>() {}; 
    Emails = snapshot.child("Emails").getValue(stringList); 
    Epabx= snapshot.child("Epabx").getValue(stringList); 
    Category_Fax= snapshot.child("Category_Fax").getValue(stringList); 
    GenericTypeIndicator<List<Persons>> personsList = new GenericTypeIndicator<List<Persons>>() {}; 
    persons = snapshot.child("Persons").getValue(personsList); 
} 

आप निर्माता बनाते हैं, तो आप इस लाइन को बदलने के लिए:

CategoryList categoryList = childSnapshot.getValue(CategoryList.class); 

इस के साथ

:

CategoryList categoryList = new CategoryList(childSnapshot); 

आप देख सकते हैं कि मैं GenericTypeIndicator का उपयोग डेटा के संग्रह के साथ काम करने के लिए, इस Firebase सूचियाँ, नक्शे के साथ काम करने के लिए एक सहायक वर्ग प्रदान करना है, सेट या एक और संग्रह।

Answer 2

बस एक सिफारिश! यह एक अच्छी डेटा संरचना नहीं है, आपको अपने डेटा को denormalize करना चाहिए। फिर आप अपने डेटा ChildEventListener या ValueEventListener द्वारा देख सकते हैं।

उदाहरण के लिए:

-Category 
--CategoryId 
---CategoryList 
---Persons 
----user1: true 
----user2: true, etc. 

-Users 
--user1Id 
---user1details 
--user2Id 
---user2details, etc. 

यहाँ अपने डेटा

Link1, denormalizing के बारे में कुछ उपयोगी लिंक को ध्यान में Link2