Append data to existing file in Windows Store 8 using JSON - json

Question

I have created an application in which I am inserting data to the file. It is working fine. Following is my code:
private async void btnSearch_Click(object sender, RoutedEventArgs e)
{
UserDetails details = new UserDetails
{
Name= TxtName.Text,
Course= TxtCouse.Text,
City=TxtCity.Text
};
string jsonContents = JsonConvert.SerializeObject(details);
StorageFolder localFolder = await ApplicationData.Current.LocalFolder.CreateFolderAsync("Storage", CreationCollisionOption.ReplaceExisting); ;
StorageFile textFile = await localFolder.CreateFileAsync("UserDetails.txt", CreationCollisionOption.ReplaceExisting);
using (IRandomAccessStream textStream = await textFile.OpenAsync(FileAccessMode.ReadWrite))
{
// write the JSON string!
using (DataWriter textWriter = new DataWriter(textStream))
{
textWriter.WriteString(jsonContents);
await textWriter.StoreAsync();
}
}
this.Frame.Navigate(typeof(BlankPage1));
}
Now I want that, when a user enter new data the data will append to the same existing file.

Answer 1

Appending data to a JSON text file would mean doing some parsing of the file to find the correct location to insert the text. That is, because JSON is structured with {} delimiters, it's not a simple matter of just appending text to the end of the file.
Given that your data doesn't look that large, the easiest thing to do is to deserialize the JSON from the existing file into memory, add your additional properties to that data structure, and then serialize back to JSON. In that case you probably just want to maintain the structure in memory during the app session, and just overwrite the file with new data whenever you need to. But of course you could also reopen the file, read/parse the JSON into memory, and then rewrite the contents.