Custom unicode sorting order for PouchDB/CouchDB Index (Mango Query)

Question

I am using PouchDB (with a Cloudant remote database) to have a local database in a dictionary web app.

I need to have an index with a custom Pashto alphabet order (using Arabic unicode letters).

The localdb.find queries with $gte (alphabetically searching with partial words) do not work well because of the irregular Unicode characters in the Pashto alphabet.

Is it possible to create a custom sort, based on the Pashto alphabet, for an index?

See Mango Query Language

Answer 1

In this reference it is mentioned that:

The most important feature of a view result is that it is sorted by key.

Assume you have a database consisting of docs with a unicodeString field inside each doc. So a sample doc would look like below:

{
    "_id":"2018-01-30-18-04-11",
    "_rev":"AE19EBC7654",

    "title":"Hello elephant",
    "unicodeString":"שלום פיל",
}

Now you can have a CouchDB view with a map function like this:

function(doc) {
    emit(doc.unicodeString, doc.title); // doc.unicodeString is key
                                        // doc.title         is value
}

The above view sorts all the docs inside the database according to its key which is doc.unicodeString. Therefore, if you use the above view, all of your docs would be sorted based on your Unicode string inside docs.

---

If you have 3 docs in database, when you query the above view, you receive a response result like this in which rows array is sorted according to key in each row:

{
    "total_rows": 3,
    "offset": 0,
    "rows": [
        {
            "key": "ארץ",
            "id": "2017-09-01-09-05-11",
            "value": "Earth"
        },

        {
            "key": "בין",
            "id": "2015-01-19-11-30-28",
            "value": "between"
        },

        {
            "key": "שלום פיל",
            "id": "2018-01-30-18-04-11",
            "value": "Hello elephant"
        }

    ]
}