how to save data in realm database javascript

Question

I am new to react-native and using realm database for my application. I want to pre-populate my data through json. I tried using componentDidMount() function and using for loop to insert data. Any guidence would be helpful.

Following is my code:

// schema file:

import booksdata from './books.json';

const Realm = require('realm');

const BooksSchema = {
    name: 'Books',
    primaryKey: 'id',
    properties: {
        id: 'int', // primary key
        name: 'string',
        author: 'string',
        publisher: 'string',
    },
};

const databaseSchema = {
    path: 'books.realm',
    schema: [BooksSchema],
    schemaVersion: 0, // optional
};

export const mountData = () => new Promise((resolve, reject) => {
    Realm.open(databaseSchema)
        .then((realm) => {
            // Create Realm objects and write to local storage
            realm.write(() => {
                booksdata.forEach(obj => realm.create(databaseSchema, {
                    id: Math.floor(Date.now() / 1000),
                    name: obj.name,
                    author: obj.author,
                    publisher: obj.publisher,
                }));
            });
        });
});

// In my index file, called componentDidMount :

 componentDidMount() {
    mountData().then().catch((error) => {
      alert(`Insert error ${error}`);
    });
  }

// I am getting following warning

Possible Unhandled Promise Rejection (id: 0):
Error: objectType must be of type 'string', got ([object Object])
Error: objectType must be of type 'string', got ([object Object])
    at sendRequest (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:62352:45)
    at sendRequest (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:62385:24)
    at Object.callMethod (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:62128:22)
    at Realm.<anonymous> (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:61983:28)
    at blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:61408:15
    at tryCallOne (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:16056:14)
    at blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:16157:17
    at blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:2884:21
    at _callTimer (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:2773:9)
    at _callImmediatesPass (blob:http://localhost:8081/d198fbe8-8b32-4037-93a7-df5a46af4f15:2809:9)

Can you provide some example code of things you tried?

Kevin Jantzer
– Kevin Jantzer

2018-05-17 18:16:43 +00:00
Commented May 17, 2018 at 18:16 — Kevin Jantzer
– Kevin Jantzer, Commented May 17, 2018 at 18:16
Hi Kevin, I have edited my question with example.

Shifali Gupta
– Shifali Gupta

2018-05-20 16:55:19 +00:00
Commented May 20, 2018 at 16:55 — Shifali Gupta
– Shifali Gupta, Commented May 20, 2018 at 16:55

geisshirt · Accepted Answer · 2018-05-17 19:41:15Z

1

You can parse your JSON data to JavaScript objects but the objects have to match your schema.

let objs = JSON.parse(data);
realm.write(() => {
    objs.forEach((obj) => realm.create('data', obj));
}

where 'data' is the name of the schema.

answered May 17, 2018 at 19:41

geisshirt

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Comments

Shifali Gupta · Accepted Answer · 2018-05-27 15:39:27Z

Thank you guys! I was making a very stupid mistake. In my schema file, while I was inserting a record in realm, I did not pass the name of my schema. Instead of databaseSchema I should pass the name of schema i.e BooksSchema.name (Books)

export const mountData = () => new Promise((resolve, reject) => {
    Realm.open(databaseSchema)
        .then((realm) => {
            // Create Realm objects and write to local storage
            realm.write(() => {
                booksdata.forEach(obj => realm.create(BooksSchema.name, {
                    id: Math.floor(Date.now() / 1000),
                    name: obj.name,
                    author: obj.author,
                    publisher: obj.publisher,
                }));
            });
        });
});

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