Close RethinkDB connection

Description

Closes connection and stops all associated callbacks and/or sync cursor.

Usage

## S3 method for class 'RethinkDB_connection'
close(con, ...)

Arguments

Close cursor

Description

Closes a given cursor and stops its associated query. Should be called on the current cursor before a new sync query is invoked on the same connection.

Usage

## S3 method for class 'RethinkDB_cursor'
close(con, ...)

Arguments

Pull next object from a cursor

Description

Pulls a datum from a given cursor, sending continuation queries when needed.

Usage

cursorNext(cursor, inBatch = FALSE)

Arguments

Value

In a default mode, a list representing the returned response JSON, or NULL if no data is available. In a batch mode, list of such lists representing the whole cache (which may be empty, corresponding to default mode's NULL).

Note

When this function empties local cache, it may ask RethinkDB for more data and hence block. Use isCursorEmpty to decide if it makes sense to call cursorNext. In case you don't need any more answers for the query, close cursor with close method.

Author(s)

Miron B. Kursa

Convert cursor into a list

Description

Converts cursor into a list. For convenience, when given anything other than cursor returns this object unchanged; this way can be used to wrap the result of $run, so that it is never a cursor.

Usage

cursorToList(x, maxResults = 10000)

Arguments

Value

A list of elements pulled from x if it is a cursor, x otherwise.

Note

The lenght of a list may be larger than maxResults because RethinkDB transmits results in batches.

Author(s)

Miron B. Kursa

Drain RethinkDB connection

Description

Drains a given RethinkDB connection, i.e. pull query responses and both call their associated callbacks (for async queries) and/or filling sync cursor local cache. Draining ends when all async queries end; the function blocks for the entire time this is happening.

Usage

drainConnection(x)

Arguments

Details

The async query callback will only fire during drainConnection or (opportunistically) cursorNext; consequently this function must be run to guarantee that installed callbacks will have a chance to fire.

Check if cursor is empty

Description

Check whether a given cursor is fully drained and will output no more datum. The function never blocks; also verifies that the underlying connection is useful.

Usage

isCursorEmpty(cursor)

Arguments

Value

TRUE if cursor has no more data to return.

Note

It is possible that cursorNext will return NULL just after isCursorEmpty returns FALSE. Changefeeds cursors (made with r()$...$changes()$...) will never become empty (provided that connection won't become broken).

Author(s)

Miron B. Kursa

Check if connection is opened

Description

Check whether a given connection is opened. Closed connections cannot be used, and will throw errors on such an attempt; their associated callbacks and/or sync cursor are dead and won't fire/produce any more data.

Usage

isOpened(x)

Arguments

Value

TRUE if connection is opened and can be used for queries, FALSE otherwise.

Author(s)

Miron B. Kursa

Open connection to a RethinkDB server

Description

Opens connection to a given RethinkDB server.

Usage

openConnection(host = "localhost", port = 28015, authKey = NULL,
  v = "V0_4")

Arguments

Value

Object of a class RethinkDB_connection, which can be passed to r()$...$run and r()$...$runAsync functions.

Print RethinkDB connection

Description

Prints a RethinkDB connection details, including a number of pending callbacks.

Usage

## S3 method for class 'RethinkDB_connection'
print(x, ...)

Arguments

Note

Never blocks.

Print cursor

Description

Prints a given cursor's status.

Usage

## S3 method for class 'RethinkDB_cursor'
print(x, ...)

Arguments

Note

Never blocks; also checks whether the underlying connection is alive.

ReQL root

Description

Creates ReQL root for building a query.

Usage

r(db, table)

Arguments

Value

ReQL root; use $ (or [[]]) to chain query terms (like r()$db("test")$table("test")). In general, anonymous attributes are passed as attributes while named as term options. In context of term arguments, named lists are treated as JSON objects (following rjson package heuristics), unnamed lists and simple vectors as JSON arrays; classes and attributes are ignored. Term options should be called in the snake case form (for instance return_changes not returnChanges), as documented for the original Python driver. To finalise, use $run or $runAsync. For a comprehensive description of all terms, see RethinkDB API reference; here we give an overview of some:

Note

ReQL is implemented as an environment, thus is mutable unlike most R objects. To this end, you can use variables for chaining like this r()->query; query$db("a"); query$table("b"); but consequently you can't use variables to make a re-usable stub, i.e., this is invalid: r()->query; query$db("a")$table("aa")$run(...) query$db("b")$table("bb")$run(...);.

If you get "trying to apply non-function" error, you likely have misspelled term name or trying to use a non-existent one.

To view raw AST (at any depth), use $query.

Author(s)

Miron B. Kursa

Examples

## Not run: 
#Connect to the RethinkDB instance
cn<-openConnection()

#Get document count in some_db's some_table
r()$db("some_db")$table("some_table")$count()$run(cn)
#...same can be done shorter
r("some_db","some_table")$count()$run(cn)

#Fetch 5 random docs from some_db's some_table...
r("some_db","some_table")$sample(5)$run(cn)->cursor
#...and present as a list`
cursorToList(cursor)

#Insert an element
r("some_db","some_table")$insert(list(id="new",a=1:10,b=list(c=1,d=2)))$run(cn)

#Close connection
close(cn)

## End(Not run)