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How to get the latest document by date/time field?

· 2 min read

I read this question on Twitter, let me answer the question in this short article.

First of all you need to be sure your documents have an attribute that contains a date ;), something like :

{
  "type" : "emp",
  "id":"001",
  "name":"John Doe",
  "hiredate":"Jan 1, 2013 8:32:00 AM"
}

To get the "latest hired employee" you need to create a view, and emit the hire date as key. The important part is to check that this date is emitted in a format that is sorted properly, for example an array of value using dateToArray function, or the time as numerical value. In the following view I am using the date as an array like that I will be able to do some grouping but this is another topic. The view looks like the following:

function (doc, meta) {
  if (doc.hiredate) {
    emit( dateToArray(doc.hiredate) );
  }
}

Now that you have a view. You can now query it using the parameters:

  • descending = true
  • limit = 1

If you use Java SDK the code will look like the following :

import com.couchbase.client.protocol.views.Query;
import com.couchbase.client.protocol.views.View;
import com.couchbase.client.protocol.views.ViewResponse;
import com.couchbase.client.protocol.views.ViewRow;
...
...
...

  View view = cb.getView("employees", "by_hiredate");
  Query query = new Query();
  query.setIncludeDocs(true);
  query.setLimit(1);
  query.setDescending(true);
  ViewResponse viewResponse = cb.query(view, query);
  for (ViewRow row : viewResponse) {
    String documentJson = row.getDocument();
  }

Finally it is important when you work with views to understand how the index are managed by the server so be sure your read the chapter "Index Updates and the stale Parameter".