CODEWITHSUNDEEP
azurexamarinxamarin.formsazure-mobile-services
Vinícius da Cruz Maia
Vinícius da Cruz Maia

Reputation: 347

How can I clear my local database using azure mobile services?

I'm using Azure Mobile Services and I want to clear local database, how can I do that?

I have a problem with my local database. When I logout in app and login with other user, the data of the previous user is loaded for current user and I don't have idea why this occurs. I use debug on server side and the server return correct data, then I believe that the problem is the local Database.

Upvotes: 3

Views: 929

Answers (2)

Bejasc
Bejasc

Reputation: 960

You can delete all of the local DB files by doing the following. 

var dbFiles = Directory.GetFiles(MobileServiceClient.DefaultDatabasePath, "*.db");
foreach (var db in dbFiles)
{
    File.Delete(db);
}

However, this would delete all data each time and cause performance issues, as every time after you did this, you'd be getting a fresh copy of the data from your Azure DB, rather than using the cached copy in the device's SQLite DB.

We typically only use this for debugging, and the reason it's in a foreach is to capture all databases created (refer to my last suggestion)

There are a few other things you could try to get around your core issue of data cross-over.

There's another reason you might be seeing this behaviour. With your PullAsync, are you passing it a query ID? Your PullAsync line should look similar to this.

GetAllFoo(string userId)
{
    return await fooTable.PullAsync("allFoo"+userId,fooTable.Where(f=>f.userId == userId));
}

Note that the query ID will be unique each time (or at least, for each user). This is used primarilly by the offline sync portion of Azure, but in combination with the Where statement (be sure to import System.Linq), this should ensure only the correct data is brought back.

You can find more information about this here.

Also, some things you may want to consider, store a separate database for each userId. We're doing this for our app (With a company ID) - so that each database is separate. If you do this, and use the correct database on logging in, there's no chance of any data cross over.

Upvotes: 1

Bruce Chen
Bruce Chen

Reputation: 18465

I'm using Azure Mobile Services and I want to clear local database, how can I do that?

For deleting your SQLite file, you could follow Deleting the backing store. Also, you could leverage the capability provided by IMobileServiceSyncTable to purge records under your offline cache, details you could follow Purging Records from the Offline Cache.

When I logout in app and login with other user, the data of the previous user is loaded for current user and I don't have idea why this occurs. I use debug on server side and the server return correct data

Since you did not provide details about your implementations (e.g. user log in/log out, user data management,etc), I would recommend you check whether your server/client side both enable per-user data store. You could use fiddler to capture the network traces when other user logging in, and make sure that the correctly user identifier (e.g. UserId) is returned, then check the query against your local database. Moreover, I would recommend you follow adrian hall's book about Data Projection and Queries.

Upvotes: 1

Related Questions