[FIXED] UI getting blocked in deserializing JSON

Issue

i am fetching data from webservice using HttpClient and storing it into Realm database. My screen automatically starts the fetching data and showing ActivityIndicator till data gets loaded and stored in database.

Now the issue is , i have lot of data to be deserialized using JsonConvert.DeserializeObject<Response>(content) as the data is huge this statement blocks/freezes my ActivityIndicator on UI screen.

how i can i deserialize object in background thread so that it doesn’t block UI.

here is my code

 var response = await Service.createService<HttpResponseMessage>("HTTP").sendData(url, jsonData);

                if (response.IsSuccessStatusCode)
                    {

                        var content = await response.Content.ReadAsStringAsync();
                        Response responseData = JsonConvert.DeserializeObject<Response>(content);
                        DB.createDB<EventType>("realm").subscribe();

                    if (responseData != null)
                        {
                            // status is ok
                            if (responseData.status.ToUpper() == OK)
                            {

                            MessagingCenter.Send<IMessage, EventType>(this, DB_EVENT, new EventTypeBuilder().status(true).requestType(url).response(responseData).Build());

                            }// status is error
                            else if (responseData.status.ToUpper() == ERROR)
                            {

                                MessagingCenter.Send<IMessage, EventType>(this, UI_EVENT, new EventTypeBuilder().status(false).requestType(url).errorMessage(responseData.errorMessage).Build());

                            }


                        }
                        else // when response is null

                            MessagingCenter.Send<IMessage, EventType>(this, UI_EVENT, new EventTypeBuilder().status(false).requestType(url).errorMessage(ERROR_RESPONSE_NULL).Build());


                    }
                    else
                    { // when some error occured
                        response.EnsureSuccessStatusCode();


                    }

Response responseData = JsonConvert.DeserializeObject<Response>(content); blocks my thread

Solution

You can run it on its own thread and await the results:

Response responseData;
await Task.Run(() => 
{
     responseData = JsonConvert.DeserializeObject<Response>(content);
     // preform your Realm database add/updates, 
     // remember you are now on a different thread so get a new Realm Instance
});

Re: Task.Run Method (Action)

Queues the specified work to run on the thread pool and returns a Task object that represents that work.

Answered By – SushiHangover

Answer Checked By – Pedro (Easybugfix Volunteer)

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