How to use realm with async fetch request? - react-native

Question

I have meet this situation for my requirements：
step 1. save data to local db which in the mobile phone (realm)
step 2. upload the local data to the server, and the server will return the data ids if success
step 3. delete the records in local db by the returned ids which get by step2
Realm.open({schema:[MySchame],encryptionKey:getRealmKey()})
.then(realm =>{
realm.write(() => {
// 1. get all step data from db
let objetcs = realm.objects('MySchema');
// 2. upload obtained data to server
if(objetcs.length > 0){
let recordArr = [];
for (let o of steps){
recordArr.push(o.get());
}
uploadDataToServer(recordArr,(res)=>{
//3. filter the uploaded steps and delete them
let uploadedSteps = realm.objects('MySchema').filtered('id=$0',res.id);
if(uploadedSteps.length > 0){
realm.delete(uploadedSteps);
}
});
}
});
realm.close();
})
.catch(error =>{
console.log(error);
});
but this is not works as expected, it seems DB is closed too early than networks success callback.
Thanks for any ideas.

Answer 1

Finally ,I use realm like this:
let realm = new Realm({schema:[JOB_SCHEMA.jobTrack],encryptionKey:getRealmKey()});
let objects = realm.objects('JobTrack');
realm.beginTransaction();
realm.delete(objects);
realm.commitTransaction();
realm.close();

Answer 2

First create a service like one below
import repository from "./realmConfig";
let CatalogsService = {
findAll: function () {
return repository.objects("CatalogsModel");
},
save: function (catalogs) {
repository.write(() => {
repository.create("CatalogsModel", catalogs);
});
},
delete: function () {
repository.write(() => {
let all = repository.objects("CatalogsModel");
repository.delete(all);
});
},
update: function (catalogs, callback) {
if (!callback) return;
repository.write(() => {
callback();
catalogs.updatedAt = new Date();
});
}
};
module.exports = CatalogsService;
where my realmConfig file is as
import Realm from "realm";
class CatalogsModel extends Realm.Object { }
CatalogsModel.schema = {
name: "CatalogsModel",
primaryKey: "id",
properties: {
id: "string",
name: "string",
url: "string",
status: "int"
}
};
class OffersModel extends Realm.Object { }
OffersModel.schema = {
name: "OffersModel",
primaryKey: "id",
properties: {
id: "string",
name: "string",
url: "string",
status: "int",
machineId: "string",
machineName: "string"
}
};
export default new Realm({
schema: [CatalogsModel, OffersModel],
schemaVersion: 1,
deleteRealmIfMigrationNeeded: true
});
Now import Service.js where you are calling async server call and do your job. For reference see below code
import CatalogService from './path/to/CatalogService .js'
//get objects
var catalogs = CatalogsService.findAll();
// fire async function , I prefer axios for network calls
Axios.post("SERVER_URL", {
data: catalogs
})
.then(function (response) {
if (response.success)
CatalogsService.delete()
}
I assume you can easily modify findAll() and delete() method as per your need