Support mango queries

[henridwyer]

CouchDB 2 has a new way to query the database without using views:

• https://blog.couchdb.org/2016/08/03/feature-mango-query/
• https://github.com/cloudant/mango

Perhaps this could be implemented as two new database functions:

• mango_query
• mango_index

[djc]

Hey, thanks for the notice. I haven't installed CouchDB 2 yet, but will likely do so soon after release. Still, I'm not sure adding APIs for Mango will be a high priority for me, personally, so it would be great if you're able to contribute some code towards this goal.

[adrian-the-git]

Just thought I'd chime in that without some mango support, there will be no way to perform a query without creating a view, as they've removed temporary views in favor of this new json-based query system.

[danballance]

I'm new to CouchDB and this project but I'm looking at trying to add these new functions mango_query and mango_index. If I have any success I'll submit a pull request.

A Mango query is just a POST request to /:db/_find containing some JSON in the body, so this shouldn't be hard to make, right?

[mraygalaxy]

Honestly, this was really dead simple to monkeypatch:

_, _, data = db.resource.post_json('_find', body={"selector" : query}, headers = {'Content-Type': 'application/json'})
return data["docs"]

Almost nearly a one-liner. Anybody wanna make a PR?

[pirr]

Maybe like in django:
For example:

data1 = db.find(field__eq='A', limit=50)
data2 = db.find(Q(field__eq='A')
                & (Q(field1__subfield1__in=['lama', 'amal'])
                    | Q(field2__subfield2__regex ="foo")), limit=40, fields=['field1', 'field2'])

I have implementation of this. If it is acceptable, I can provide my implementation.
Q obj - https://github.com/pirr/alt_couch/blob/c690771f729c38ac39041d4fea981b44623a0748/_libs/vb/couch.py#L14
find method - https://github.com/pirr/alt_couch/blob/c690771f729c38ac39041d4fea981b44623a0748/_libs/vb/couch.py#L222
Sorry for my terrible english.

[djc]

I would like to add an implementation to CouchDB-Python. If you can provide one that fits into the library and has comments in English, I could probably review it.

[pirr]

I added filter method (mango query) with comments:
pirr@6f051bc

[djc]

Looks pretty good, do you want to do a pull request for this?

[pirr]

#324 this is my first pool reguest. If there are comments, please, I will correct