README.md

In joyofdata/rmongodbHelper: What the package does (short line)

rmongodbHelper

The recommended package for using MongoDB with R is "rmongodb". Sadly there is bug in this package preventing an easy construction of BSONs containing arrays from lists or JSON-objects. The suggested method for bypassing this issue is building up a mongo.bson.buffer from scratch. That's kind of cumbersome. For that purpose I composed this small package to allow easy generation of BSONs from JSON or a list().

To give you an example - let's assume we would like to create a BSON for searching documents who feature a key "a" either holding value 1 or 2: {$or: [{a=1},{a=3}]}

The sequence of mongo.bson.buffer statements would be this:

buf <- mongo.bson.buffer.create()

# "$or":[ ...
mongo.bson.buffer.start.array(buf, "$or")

# dummy name "0" for object in array
# "0": { ...
mongo.bson.buffer.start.object(buf, "0")
# "a":1
mongo.bson.buffer.append.int(buf, "a", 1)
# ... }
mongo.bson.buffer.finish.object(buf)

mongo.bson.buffer.start.object(buf, "1")
mongo.bson.buffer.append.int(buf, "a", 3)
mongo.bson.buffer.finish.object(buf)

# ...]
mongo.bson.buffer.finish.object(buf)

q <- mongo.bson.from.buffer(buf)

Using the function rmongodbHelper::json_to_bson():

json_to_bson('{
  "$or": [
    {"a":1},
    {"a":3}
  ]
}')

For detailed information on how to use this package please have a look at the following answers on stackoverflow.com:

• http://stackoverflow.com/a/25239583/562440
• http://stackoverflow.com/a/25473782/562440
• http://stackoverflow.com/a/25473070/562440

Nonetheless this package does not aim at being extensive - it really is just a workaround until the issue in rmongodb has been fixed. Having said that you are welcome to extend, correct or improve the code or just send me suggestions on what to add.

joyofdata/rmongodbHelper documentation built on May 19, 2019, 10:43 p.m.