Better query support

[dylanlott]

Querying should be much more robust by default.

• User's should be able to populate and accomplish relational data using their own queries.
• User's should be able to use advanced querying mechanics such as $IN and $WHERE and $EXISTS

[GabeAboy]

PR
#10

Research
https://restdb.io/docs/querying-with-the-api#queryXexamples
https://docs.mongodb.com/manual/tutorial/query-documents/

[GabeAboy]

Logical Operators
[X] $not | Negation logical operator | {"field" : {"$not" : val}}
[X] $in | Match any value in array | {"field" : {"$in" : [value1, value2, ...]}}
---/ubermind/?=value1/value2
[X] $nin | Not match any value in array | {"field" : {"$nin" : [value1, value2, ...]}}
[ ] $regex | Match field | {"field" : {"$regex" : ".*"}}
[X] $or | Logical operator | {"$or": [{"status": "GOLD"}, {"status": "SILVER"}]}
---Docs say use $in in replace for $or

[X] $and | Logical operator | {"$and": [{"status": "GOLD"}, {"sales": 1000}]}
[X] $where | Match any value | {"field" : value}
---/ubermind/?=value

[GabeAboy]

I might change the request string to look something like this https://restdb.io/docs/querying-with-the-api#queryXexamples. What do you think @dylanlott

TLDR
It expects the user to use an http string such as,
http://localhost:3000/ubermind/todos?q={"task" : {"$in" : ["Learn Spanish", "Learn Ubermind"]}}
Which is nice, but I think the goal is to reduce the amount of knowledge of mongo necessary to use ubermind. Using above is super easy but puts the responsibility to the client in injecting a properly formatted query argument.

I want to make it simpler, but I don't know-how. This is my initial thought. I might change the / to ||
What is set up in the PR
http://localhost:3000/ubermind/todos?task=Learn Spanish/Learn ubermind

Or use the req.body for it?

[GabeAboy]

Conditional Operators

Priority
[X] $gt | > | {"salary": {"$gt": 10000}}
[X] $gte | >= | {"salary": {"$gte": 10000}}
[X] $lt | < | {"salary": {"$lt": 10000}}
[X] $lte | <= | {"salary": {"$lte": 10000}}
[ ] $bt | >= value <= | {"salary": {"$bt": [5000, 7500]}}

Extra
[ ] $exists | Check if field exists | {"field": {"$exists": true|false}}
---/ubermind/?task=exists
[ ] $exists (array) | Check if array field exists or is empty | {"field.0": {"$exists": true|false}}
---/ubermind/?task=one||two||three
HOW?
[ ] $elemMatch | Array element matching | {"contact":{"$elemMatch":{"name":"Anderson", age:35}}}
[ ] $distinct | Array with unique element values | {"$distinct": "name"}
---/ubermind/?task=
HOW?