Update Many command implementation

[maheshrajamani]

What this PR does:
Update many command implementation
Response change for UpdateOne and FindOneAndUpdate
Which issue(s) this PR fixes:
Fixes #145 #168 and #169

Checklist

• [X ] Changes manually tested
• [X ] Automated Tests added/updated
• Documentation added/updated
• CLA Signed: DataStax CLA

[tatu-at-datastax]

I think it all looks good, but I am unsure if that calculation of updated could lead to operations skipped -- I think it does?

[vkarpov15]

Another detail worth confirming: do additional fields in the filter get added to the resulting document on upsert? For example, if this is "filter" : {"_id": "doc6", "answer": 42}, does the resulting document have an answer property?

[tatu-at-datastax]

Good question: I think method "getEmptyDocument(s)" (renamed as "getNewDocument") is only inserting document id?

[maheshrajamani]

@vkarpov15 During upsert the getNewDocument() method creates document populated with _id if it is part of the filter condition. So the resulting document will not have the answer property populated based on the filter condition. I will add a test case for this in a separate PR.

[vkarpov15]

@maheshrajamani this is a somewhat important detail. Upserting should apply any fields from the filter that don't have a non- $eq query operator. Below is some output from the mongodb shell that shows this behavior.

Mongoose does use this behavior for setting schema defaults on upsert.

MongoDB Enterprise > db.tests.countDocuments({})
0
MongoDB Enterprise > db.tests.updateOne({ _id: 'foo', answer: 42 }, { $set: { bar: 'baz' } }, { upsert: true })
{
	"acknowledged" : true,
	"matchedCount" : 0,
	"modifiedCount" : 0,
	"upsertedId" : "foo"
}
MongoDB Enterprise > db.tests.findOne()
{ "_id" : "foo", "answer" : 42, "bar" : "baz" }
MongoDB Enterprise > 
MongoDB Enterprise > db.tests.updateOne({ _id: 'foo', answer: { $eq: 42 }, count: { $gte: 42 } }, { $set: { bar: 'baz' } }, { upsert: true })
{
	"acknowledged" : true,
	"matchedCount" : 0,
	"modifiedCount" : 0,
	"upsertedId" : "foo"
}
MongoDB Enterprise > db.tests.findOne()
{ "_id" : "foo", "answer" : 42, "bar" : "baz" }
MongoDB Enterprise > 

[maheshrajamani]

@vkarpov15 Got it. Will add equals condition filter fields to the newly created document and will submit a new PR.

[maheshrajamani]

Resolved in PR #200