Questions about the LocalDataStore in Parse

Question

I am developing in iOS with Parse. My app required offline operation, so I had developed my own solution. However, Parse's introduction of the LocalDataStore obviates the need for my own solution. Since this is not released in iOS yet, I can only rely on documentation to prepare for this. I asked these questions on the Parse forum a week ago and the questions have been completely ignored by Parse. Can anyone answer these via experience with the Android version?

1) Objects pointed to by pointers and PFRelations will be pinned along with the pinned object. (That's correct, right?) Will PFFiles be pinned along with the object? Will the file data be locally available?

2) When a pinned object is modified, you have to SaveEventually it to push the changes to the Server, right? Does a Save on a pinned object save locally? Or does it do an "on-line" save?

3) When changes occur elsewhere to a pinned object, how do those changes get propagated to the pinned object in the LocalDataStore? Does the programmer have to explicit fetch the changes, or will it happen automatically?

4) Does the concept of logging in apply to the LDS? Do the ACLs operate in the LDS? Or does the local code have access to all objects in the LDS?

-Bob

Answer 1

I can give a basic answer from the Android side, but keep in mind the details may change as the Parse.com iOS version of LDS is released. My answers below come direct from the API docs are are bolded where I quote directly.

Let's go point by point:

1) Objects pointed to by pointers and PFRelations will be pinned along with the pinned object. (That's correct, right?) Will PFFiles be pinned along with the object? Will the file data be locally available?

Yes. From the Android docs: "Pinning a ParseObject is recursive, just like saving, so any objects that are pointed to by the one you are pinning will also be pinned."

2) When a pinned object is modified, you have to SaveEventually it to push the changes to the Server, right? Does a Save on a pinned object save locally? Or does it do an "on-line" save?

Again, from the Android docs this appears to be Yes. "Once you've saved some changes locally, there are a few different ways you can save those changes back to Parse over the network. The easiest way to do this is with saveEventually. When you call saveEventually on a ParseObject, it will be pinned until it can be saved. The SDK will make sure to save the object the next time the network is available."

3) When changes occur elsewhere to a pinned object, how do those changes get propagated to the pinned object in the LocalDataStore? Does the programmer have to explicit fetch the changes, or will it happen automatically?

The Android docs are pretty quiet about this process, but it's a safe bet you will have to query the server to synchronize the local datastore, the same way you do now when you have a local instance of an object after a query. That's all all the local data store is - a very persistent version of queried data.

4) Does the concept of logging in apply to the LDS? Do the ACLs operate in the LDS? Or does the local code have access to all objects in the LDS?

Logging in still applies, as does ACLs, as far as I can tell. The object permissions are still required for the local data. I haven't confirmed this with a test project in Eclipse, but the docs allude to this being the case.

A final note: The CEO of Parse, Ilya Sukhar, weighed in on the Google Group 3 days ago saying the iOS LDS is definitely on it's way. Here's hoping it's soon!