Purging entities in the local database

[scout208]

Hi, the old version of this library which was under Azure Mobile Apps (https://github.com/Azure/azure-mobile-apps?tab=readme-ov-file) had a method that could be used to wipe all the data from the local table (https://learn.microsoft.com/en-us/previous-versions/azure/developer/mobile-apps/azure-mobile-apps/howto/client/dotnet#purging-entities-in-the-local-database). Is this something that has been considered being added to this library?

[Vroomer]

You have full access to the local db through EF Core DbContext. You can easily remove any data as you please. Just be sure to call SaveChanges without pushing them to remote API - there is SaveChanges overload method for this:
await dbContext.SaveChangesAsync(true, addToQueue: false);

You might also want to reset or edit the delta token for given table, if you do this. Those are as well fully accesible through DbContext.
dbContext.DatasyncDeltaTokens

[adrianhall]

something like:

foreach (var id in dbContext.MyEntities.Select(e => e.Id))
{
    var entity = new MyEntity { Id = id };
    dbContext.MyEntities.Attach(entity);
    dbContext.MyEntities.Remove(entity);
}
foreach (var deltaToken in dbContext.DatasyncDeltaTokens.Where(x => x.EndsWith("MyEntity")))
{
   dbContext.DatasyncDeltaTokens.Remove(deltaToken);
}
await dbContext.SaveChangesAsync(true, false);

[scout208]

Thanks. The addToQueue parameter was what I was missing. I didn't see that overload before.

@adrianhall Why are you attaching the entities and then removing them? For me this code worked:

dbContext.MyEntities.RemoveRange(dbContext.MyEntities);
dbContext.DatasyncDeltaTokens.RemoveRange(dbContext.DatasyncDeltaTokens);

await dbContext.SaveChangesAsync(true, false);

I just want to make sure there isn't some problem with doing it this way that I am missing.

[adrianhall]

RemoveRange attaches all the data and then removes the records. Attach/Remove only sets the ID and doesn't load the other data. In "large" datasets (where each individual record is large), this can be a significant win.