Deletion Strategy¶

Introduction:¶

To delete a case in Editor, click the "Trashcan" button to the right of the case ID in the "breadcrumbs" area at the top of the case document. This adds archived:true to the case document as well as all eventForm responses for the case.

The client search index code filters out docs with the archived:true flag.

Once you start using this deletion feature, create an update using the following code:

await window['T'].search.createIndex()
await userDb.query('search', { limit: 1 })

This code will rebuild the index on client in order to return the correct results when running a search on a tablet that already has data collected on it.

Difference between Delete and Archive feature in Editor¶

In Editor, the "Delete" and "Archive" buttons both add the archived:true flag to a document, but they do differ in the following ways: - Deleting a case creates "stub" documents with minimal properties. The case doc keeps its inputs so search works properly. - A case that has been archived can be un-archived. The only difference between an archived doc and a non-archived doc is the presence of the archived:true flag.

Deleting a record in Tangerine manually on the server¶

When using this manual method, deletions on the client do not follow deletions on the server.

Open the document in Fauxton. Click the "Delete" button on the right hand side of the header to delete. This will create a bare-bones document that includes the _deleted" flag. By default, deleted docs are not included in replication; however, there is a way to query them (see below).

Testing deletions¶

When you open a new case on client, don't enter any data, but click next. The app does create a case and it can be sync'd. Although the case does not display in the case home search results on client, this record does get output on the server via CSV export.

When you use the Delete button in Fauxton, it removes all data except for this tombstone:

{
  "_id": "6c27f5c8-6e08-4245-ae57-cef7d63099de",
  "_rev": "2-28819102bb2ec0e3390f28d94467212a",
  "_deleted": true
}

When the client syncs, it does not get this new rev.

Viewing deletions:¶

curl -X POST -H "content-Type: application/json" "http://admin:password@localhost:5984/group-2627a0a7-852a-4f51-9d5d-b7ae53130976/_changes?filter=_selector" -d '{"selector": {"_deleted": true}}'

response:

{
  "results": [
    {
      "seq": "16-g1AAAAIBeJyVz0sOgjAQBuABjI-FZ9AjUJpaXMlNtC8CBNuFutab6E30JnqTWh4J0UQDm5nkz8yXmRIAplkgYa6NNlIl2mTmcCxd7DPgC2ttkQVsvHfBhIRrgST5Hv6xzpeu8k0reLWgMBacx32FpBK2reDXAltRRGLcV9hVwvlDEDiKKev7hR65ChfXHHLtFIIICzkdpNwa5d4pVDIs0mG3PBrlWSlQK5HCKUJIwuykpUpzreRf4dUItmBe8QYjK50u",
      "id": "6c27f5c8-6e08-4245-ae57-cef7d63099de",
      "changes": [
        {
          "rev": "2-28819102bb2ec0e3390f28d94467212a"
        }
      ],
      "deleted": true
    }
  ],
  "last_seq": "20-g1AAAAIfeJyV0F0OgjAMAOAp_j54Bj0CY5mDJ7mJbusIEtwe1Ge9id5Eb6I3wTFIiBoNvLRJ035pmyOEJqkHaKaNNqBibVKzP-S23OdIzIuiyFKPj3a2MKZ-JDHQz-Yf42Jho1jVQs8JihApRNhWiEthXQt9J_AlwzQkbYVNKZzeBEmCkPG2V-iBjehsk0UujUIx5b5gnZRrpdwahQEnMum2y71SHqWCnBIokmCMAU2PGlSy1Qr-Cs9KcD8ZOiEBSUX09dXsBf6mphA",
  "pending": 0
}

To get deleted doc, use the rev: http://localhost:5984/group-2627a0a7-852a-4f51-9d5d-b7ae53130976/6c27f5c8-6e08-4245-ae57-cef7d63099de?rev=2-28819102bb2ec0e3390f28d94467212a

How to create deletions on client¶

Potential steps: - Use the _changes example above to get a list of deleted docs on the server. - Process the results and use the pouchdb remove function on each doc/rev.

Restoring deleted documents¶

Using couchdb-wedge¶

Using the restore-deleted-doc command from couchdb-wedge, we can give it a URL, db, and docId to restore.

npm install -g couchdb-wedge
wedge restore-deleted-doc --url http://username:password@source-server.com:5984 --db my-db --docId 1234

Using curl¶

Get the revs for the deleted doc:

curl -H 'Accept: application/json' 'http://server:5984/group-uuid-devices/6013f414-6401-4903-b0f9-fb862779cc3f?revs=true&open_revs=all'

Command returns:

{
  "_id": "6013f414-6401-4903-b0f9-fb862779cc3f",
  "_rev": "4-46fb2d064595bb6b2068b20450f2a3f9",
  "_deleted": true,
  "_revisions": {
    "start": 4,
    "ids": [
      "46fb2d064595bb6b2068b20450f2a3f9",
      "59e68396a5b632f62e3ab3930dda3d45",
      "09463546fcf1177408821fccada40269",
      "e3af953eab52ed5f3d56c9f57fdeb2f9"
    ]
  }
}

Get the previous rev id by subtracting 1 from the _revisions.start property and appending the value of the second element in the _revisions.id array:

Result should be 3-59e68396a5b632f62e3ab3930dda3d45

Now query the server for that _rev:

http://server/group-uuid-devices/6013f414-6401-4903-b0f9-fb862779cc3f?rev=3-59e68396a5b632f62e3ab3930dda3d45

To overwrite the old deleted entry you have to post or put back the document with the correct id and the latest revision number (not the pre delete revision number, but the revision number the document has now it has been deleted).

An easier way to do this is to use the COPY command:

curl -X COPY "server:5984/group-uuid-devices/6013f414-6401-4903-b0f9-fb862779cc3f?rev=3-59e68396a5b632f62e3ab3930dda3d45" -H "Destination: 6013f414-6401-4903-b0f9-fb862779cc3f"