Re: Comparing Current Snapshot and Committed Snapshot

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Mon Apr 25 2005 - 22:21:29 EDT

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    On Apr 25, 2005, at 10:06 PM, Eric Schneider wrote:

    > Hi,
    >
    > Is there public API anywhere that will compare a CayenneDataObject's
    > committed and current snapshot? I know something similar happens
    > internally before a commit. Is there some commons api that diffs
    > Maps?
    >
    > Thanks!
    > e.

    Yep. DataRow has "diff" methods:

    DataObject object = ...;
    DataContext context = object.getDataContext();

    DataRow committed =
    context.getObjectStore().getSnapshot(object.getObjectId(), context);
    DataRow current = context.currentSnapshot(object);
    DataRow diff = current.createDiff(committed);

    // "createDiff" assumes that no keys are missing from snapshot.
    // To be 100% confident we can create the reverse diff... Probably an
    overkill.
    // DataRow reverseDiff = committed.createDiff(current)

    Internally this method is not used as widely as it should due to a
    number of special cases accumulated over time. I hope this will change
    in the future...

    Andrus

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