Creating Complex Views

[kde...@gmail.com]

I have a situation where i am trying to use "psuedo" joins where the doc types are ticket and schedule where I want to emit both types of documents.

The schedule document has eventid, year, minute, second and the ticket document has the schedule id.

In the if statement for a schedule doc, I will emit([doc[eventid], doc[year], doc[month], doc[day], doc[scheduleid], name)

In the if statement for a ticket doc, I want to lookup the eventid, year, month, day from the scheduleid in the ticket document. then emit([schedule.event, schedule.year, schedule.month, schedule.day, doc["schedule"], NULL).

I will reduce to get ticket count per event.  My question is to handle how to look up a schedule document from within mapblock.  I have got "thread exception" error in my first go at this, but before I continue to develop solution I wanted to make sure this is the best solution.  Obviously, I can put event, year, month, day in ticket documents but this is redundant information and may lead to errors if I have to change dates of schedule, but I wanted to know if it was a good practice to look up information on another document inside the mapblock on background thread. I realize that the examples are not written in perfect objective c syntax.

I hope I am making myself clear. Please respond.

[Jens Alfke]

On May 21, 2015, at 10:28 AM, kde...@gmail.com wrote:

My question is to handle how to look up a schedule document from within mapblock.

You can’t, or rather, it’s illegal. In map/reduce, the map function has to be a “pure” function with no dependencies on any state other than its inputs, i.e. the document properties. Otherwise the index can become invalid.

In your case, if that schedule document changes in a way that would change the data emitted for the ticket document, the ticket document will not be re-indexed (only docs that change are re-indexed) so the index data will be out of date.

—Jens

[kde...@gmail.com]

Jens,

Thanks for the quick response.

Can you offer an alternative to count tickets associated with schedules, and order them by date? When ticket does not have date information? Should I store the date information into ticket documents?

[Jens Alfke]

On May 21, 2015, at 12:57 PM, kde...@gmail.com wrote:

Can you offer an alternative to count tickets associated with schedules, and order them by date? When ticket does not have date information? Should I store the date information into ticket documents?

Create a view that indexes the tickets with scheduleID as the primary key, then group at level=1 to get the count of tickets for each schedule.

Then create a view that indexes schedules with date as the key.

You’ll need to combine the two together to get ticket count by date. For example, query the first view and create a dictionary that maps schedule ID to count, then query the second view and for each schedule look up the count using the dictionary.

—Jens

[kde...@gmail.com]

Thanks. I did not think using two views was an option because I am using CBLTablesource, using one view as the datasource and the other to create a dictionary makes sense.

[Jens Alfke]

On May 21, 2015, at 2:03 PM, kde...@gmail.com wrote:

Thanks. I did not think using two views was an option because I am using CBLTablesource, using one view as the datasource and the other to create a dictionary makes sense.

That class is just a utility to help with the most common way of binding a table to a view. It’s not complex, and we encourage developers to copy and extend the source code if they need to go beyond what it can do.

—Jens

[kde...@gmail.com]

Do you recomend using CBLUITablesource? It seems to work well with live queries. I have another situation where I want to use a regular UITableview in order to use sections, and my question is about CBLLiveQuery. How do you use CBLLiveQuery with a regular UITableview. I have not had any luck making it work. I have made CBLQuery work correctly by enumerating the query and storing objects in an array to use for UiTableview data source. But I do not think my data will refresh when something changes like CBLLiveQuery. Any thoughts to share about this topic. Basically does live queries only work with CBLTableSource.
Thanks again.

[Jens Alfke]

On May 23, 2015, at 8:23 PM, kde...@gmail.com wrote:

How do you use CBLLiveQuery with a regular UITableview. I have not had any luck making it work.

CBLUITableSource isn’t special; it’s just a simple implementation of binding a live query to a table view. If you’re having trouble building your own, feel free to copy its source code and extend or adapt it.

—Jens