Realm android map date field using createObjectFromJson()

Question

Started working on Realm database(Android), I am calling wcf service which response is as,

{
   "ProductId": 1,
  "ProductCategory": " CategorY_result",
  "ProductName": "Admission",
  "Priority": "High",
  "EnteredBy": null,
  "EnteredDate": "/Date(1224043200000)/",
}

and model for this as,

 public class Product extends RealmObject
 {
  @PrimaryKey
  private long ProductId;

  private String ProductCategory;
private String ProductName;
private String Typeofcollege;
private String Priority;
 private Date EnteredDate;    // is it mapped to Date directly ?
}

I want Date data type for EnteredDate field, i am doing steam parsing using createObjectFromJson() method

realm.createObjectFromJson(Product.class,inputStream);

but getting null value for EnteredDate. how can tackle this

Answer 1

WCF services supply Dates over JSON in a strange format, you have to format it by writing your own serialisation and deserialisations code (i.e. "/Date(12345678989+0000)/")

Below in the code snippet I have defined how to write an object into Realm Db using Gson Lib to parse your WCF date format into java date format.

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;

import java.io.IOException;
import java.util.Date;

import io.realm.Realm;
import io.realm.RealmResults;

public class MainActivity extends AppCompatActivity {

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

        // Initialize Realm
        Realm.init(this);

        // Get a Realm instance for this thread
        Realm realm = Realm.getDefaultInstance();

        //Gson instance for date matching
        Gson gson = new GsonBuilder().registerTypeAdapter(Date.class, new NetDateTimeAdapter()).create();

        //example of json you want to match
        String stringObj = "{\n" +
                "      \"ProductId\": 1,\n" +
                "      \"ProductCategory\": \" CategorY_result\",\n" +
                "      \"ProductName\": \"Admission\",\n" +
                "      \"Priority\": \"High\",\n" +
                "      \"EnteredBy\": null,\n" +
                "      \"EnteredDate\": \"/Date(1224043200000)/\"\n" +
                "     }";

        //Using gson lib parsing json into gson into WcfObject
        Product object = gson.fromJson(stringObj, Product.class);


        //write the object into realm
        realm.beginTransaction();
        realm.insertOrUpdate(object);
        realm.commitTransaction();

        RealmResults<Product> result = realm.where(Product.class).findAll();

        for (Product obj : result) {
            //printing it to see weather it is working or not
            Log.e("value", obj.toString());
        }

    }


    private static class NetDateTimeAdapter extends TypeAdapter<Date> {
        @Override
        public Date read(JsonReader reader) throws IOException {
            if (reader.peek() == JsonToken.NULL) {
                reader.nextNull();
                return null;
            }
            Date result = null;
            String str = reader.nextString();
            str = str.replaceAll("[^0-9]", "");
            if (!TextUtils.isEmpty(str)) {
                try {
                    result = new Date(Long.parseLong(str));
                } catch (NumberFormatException e) {
                }
            }
            return result;
        }

        @Override
        public void write(JsonWriter writer, Date value) throws IOException {
            // Nah..
        }
    }
}

Product class code

import java.util.Date;

import io.realm.RealmObject;
import io.realm.annotations.PrimaryKey;

public class Product extends RealmObject {
        @PrimaryKey
        private int ProductId;
        private String ProductCategory;
        private String ProductName;
        private String EnteredBy;
        private Date EnteredDate;

        @Override
        public String toString() {
                return "WcfObject{" +
                        "ProductId=" + ProductId +
                        ", ProductCategory='" + ProductCategory + '\'' +
                        ", ProductName='" + ProductName + '\'' +
                        ", EnteredBy='" + EnteredBy + '\'' +
                        ", EnteredDate=" + EnteredDate.toString() +
                        '}';
        }
}

All the above given code is described with the comment. Let me know if any clarification is needed.