mongo.find: Find records in a collection
In jonkatz2/rmongodb: R-MongoDB driver

Description Usage Arguments Details Value See Also Examples

Find records in a collection that match a given query.

1 2	mongo.find(mongo, ns, query = mongo.bson.empty(), sort = mongo.bson.empty(), fields = mongo.bson.empty(), limit = 0L, skip = 0L, options = 0L)

`mongo`	(mongo) a mongo connection object.
`ns`	(string) namespace of the collection from which to find records.
`query`	(mongo.bson) The criteria with which to match the records to be found. The default of mongo.bson.empty() will cause the the very first record in the collection to be returned. Alternately, `query` may be a list which will be converted to a mongo.bson object by `mongo.bson.from.list()`. Alternately, `query` may be a valid JSON character string which will be converted to a mongo.bson object by `mongo.bson.from.JSON()`.
`sort`	(mongo.bson) The desired fields by which to sort the returned records. The default of mongo.bson.empty() indicates that no special sorting is to be done; the records will come back in the order that indexes locate them. Alternately, `sort` may be a list which will be converted to a mongo.bson object by `mongo.bson.from.list()`. Alternately, `sort` may be a valid JSON character string which will be converted to a mongo.bson object by `mongo.bson.from.JSON()`.
`fields`	(mongo.bson) The desired fields which are to be returned from the matching record. The default of mongo.bson.empty() will cause all fields of the matching record to be returned; however, specific fields may be specified to cut down on network traffic and memory overhead. Alternately, `fields` may be a list which will be converted to a mongo.bson object by `mongo.bson.from.list()`. Alternately, `fields` may be a valid JSON character string which will be converted to a mongo.bson object by `mongo.bson.from.JSON()`.
`limit`	(as.integer) The maximum number of records to be returned. A limit of 0L will return all matching records not skipped.
`skip`	(as.integer) The number of matching records to skip before returning subsequent matching records.
`options`	(integer vector) Flags governing the requested operation as follows: mongo.find.cursor.tailable mongo.find.slave.ok mongo.find.oplog.replay mongo.find.no.cursor.timeout mongo.find.await.data mongo.find.exhaust mongo.find.partial.results

See http://www.mongodb.org/display/DOCS/Querying.

(mongo.cursor) An object of class "mongo.cursor" which is used to step through the matching records.

Note that an empty cursor will be returned if a database error occurred.
mongo.get.server.err() and mongo.get.server.err.string() may be examined in that case.

mongo.cursor,
mongo.cursor.next,
mongo.cursor.value,
mongo.find.one,
mongo.insert,
mongo.index.create,
mongo.update,
mongo.remove,
mongo,
mongo.bson.

mongo <- mongo.create()
if (mongo.is.connected(mongo)) {
    buf <- mongo.bson.buffer.create()
    mongo.bson.buffer.append(buf, "age", 18L)
    query <- mongo.bson.from.buffer(buf)

    # Find the first 100 records
    #    in collection people of database test where age == 18
    cursor <- mongo.find(mongo, "test.people", query, limit=100L)
    # Step though the matching records and display them
    while (mongo.cursor.next(cursor))
        print(mongo.cursor.value(cursor))
    mongo.cursor.destroy(cursor)


    # shorthand: find all records where age=32, sorted by name,
    # and only return the name & address fields:
    cursor <- mongo.find(mongo, "test.people", list(age=32),
                         list(name=1L), list(name=1L, address=1L))
}