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LUA-RESTY-MOONGOO

Adding some lua moondust to the mongo goo

What is it?

Lua mongodb driver, highly inspired by perl-mango.
Also, möngö is mongolian currency, and mungu is god in Swahili.

Table of Contents

• Requirements
• Installation
• Usage
  • Synopsis
  • Moongoo methods
    • new
    • close
    • db
  • Database methods
    • collection
    • gridfs
    • cmd
  • Collection methods
    • create
    • drop
    • rename
    • options
    • full_name
    • stats
    • index_information
    • ensure_index
    • drop_index
    • find
    • find_one
    • find_and_modify
    • insert
    • update
    • remove
    • save
    • map_reduce
    • aggregate
  • Cursor methods
    • clone
    • tailable
    • await
    • comment
    • hint
    • max_scan
    • max_time_ms
    • read_preference
    • snapshot
    • sort
    • skip
    • limit
    • next
    • rewind
    • all
    • count
    • explain
    • distinct
  • GridFS methods
    • list
    • remove
    • find_version
    • open
    • create
  • GridFS file methods
    • content_type
    • filename
    • md5
    • metadata
    • date
    • length
    • chumk_size
    • seek
    • tell
    • read
    • slurp
    • write
    • close
• Authors
• Sponsors
• Copyright and License

Requirements

• LuaJit or Lua with BitOp
• lua-libbson
• lua-posix

To use outside of OpenResty you'll also need:

• LuaSocket
• LuaCrypto

Usage

Synopsis

local moongoo = require("resty.moongoo")
local cbson = require("cbson")

local mg, err = moongoo.new("mongodb://user:password@hostname/?w=2")
if not mg then
  error(err)
end

local col = mg:db("test"):collection("test")

-- Insert document
local ids, err = col:insert({ foo = "bar"})

-- Find document
local doc, err = col:find_one({ foo = "bar"})
print(doc.foo)

-- Update document
local doc, err = col:update({ foo = "bar"}, { baz = "yada"})

-- Remove document
local status, err = col:remove({ baz = "yada"})

-- Close connection or put in OpenResty connection pool

mg:close()

NOTE

You should use cbson datatypes for anything other than strings, floats and bools.
All lua numbers are stored as floats.
Empty arrays are treated and stored as empty documents (you can use cbson.array() to forcibly store empty array in mongo).
nil lua values are ignored and not stored, due to nature of lua, use cbson.null.
nil values from mongo are decoded as cbson.null (use somevar == cbson.null() for comparison)

Moongoo methods

new

<moongoo_obj>mgobj, <string>error = moongoo.new(<string>connection_string)
Creates new Moongoo instance
Refer to Connection String URI Format
Currently supported options are:

• w - default is 0
• wtimeoutMS - default is 1000
• journal - default is false
• authMechanism - default depends on mongodb version
• socketTimeoutMS - default is nil. It controls both connect and read/write timeout.
  It's set to nil by default so you can control connect and read/write separately
  with OpenResty lua_socket_connect_timeout, lua_socket_send_timeout and lua_socket_read_timeout.
• ssl - default is false
  Use ssl for connection. Currently there's no support for CA or client certificates.

Moongoo tries really hard to be smart, and opens connection only when needed,
searches for master node in replicaset, and uses relevant to mongodb version auth mechanism.
Downside is: you can't currently issue queries to slave nodes.

close

mgobj:close()
Closes mongodb connection (LuaSocket) or puts it in connection pool (OpenResty)
Issuing new read/write commands after will reopen connection.

db

<database>dbobj = mgobj:db(<string>name)
Selects database to use.

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Database methods

collection

<collection>colobj = dbobj:collection(<string>name)
Returns new collection object to use.

gridfs

<gridfs>gridfsobj = dbobj:gridfs(<optional string>prefix)
Returns new gridfs object to use.
Default prefix id 'fs'.

cmd

<document>result, <string>error = dbobj:cmd(<string or table>command, <table>params)
Runs database commans.
command is either string with command name, or table { command = value }.
Params are command parameters. For example, given distinct mongodb command:

  local result, error = dbobj:cmd( { distinct = "some.collection" }, { key = "somekey } )

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Collection methods

create

<collection>new_colobj, <string>error = colobj:create(<string>name)
Creates new collection and returns new collection object for it.

drop

<bool>result, <string>error = colobj:drop()
Drops collection.

rename

<collection>new_colobj, <string>error = colobj:rename(<string>newname, <bool>drop)
Renames collection, optionally dropping target collection if it exists.

options

<document>result, <string>error = colobj:options()
Retuns collection options.

full_name

<string>result = colobj:full_name()
Returns full collection namespace (e.g. database.collection).

stats

<document>result, <string>error = colobj:stats()
Returns collection statistics.

index_information

<array>result, <string>error = colobj:index_information()
Returns info about current indexes.

ensure_index

<bool>result, <string>error = colobj:ensure_index(<array>indexes)
Creates new index.
indexes should be an array, even if it has 1 value.. Refer to mongo docs for index format.
Note, that in moongoo, index names are optional, moongoo will create them for you based on keys.

drop_index

<bool>result, <string>error = colobj:drop_index(<string>index)
Drops named index from collection.
Refer to mongo docs for index format.

find

<cursor>cursorobj = colobj:find(<table or cbson.oid>query, <table>fields)
Returns new cusor object for query.

find_one

<document>doc, <string>error = colobj:find_one(<table or cbson.oid>query, <table>fields)
Returns first document conforming to query.

find_and_modify

<document>doc, <string>error = colobj:find_and_modify(<table or cbson.oid>query, <table>opts)
Modifies document, according to opts
and returns (by default) old document.

insert

<array>ids, <string or cbson.uint>error_or_number = colobj:insert(<array or table>docs)
Inserts new document(s) and returns their id's and number of inserted documents.

update

<cbson.uint>number, <string>error = colobj:update(<table or cbson.oid>query, <table>update, <table>flags)
Updates document, according to query and flags.
Supported flags are:

• multi - update multiple documents (default - false)
• upsert - insert document, if not exists (default - false)

Returns number of updated documents

remove

<cbson.uint>number, <string>error = colobj:remove(<table or cbson.oid>queryquery, <bool>single)
Removes document(s) from database.
Returns number of removed documents.

save

<cbson.oid>id = colobj:save(<table>document)
Saves document to collection.
Basically, this performs update with upsert = true, generating id if it not exist.
See here for explanation.

map_reduce

<document>doc, <string>error = colobj:map_reduce(<string>map, <string>reduce, <table>flags)
<collection>new_colobj, <string>error = colobj:map_reduce(<string>map, <string>reduce, <table>flags)
Performs map-reduce operation and returns either document with results,
or new collection object (if map-reduce out flag set to collection name).

aggregate

<document>explain, <string>error = colobj:aggregate(<array>pipeline, <table>opts)
<collection>new_colobj, <string>error = colobj:aggregate(<array>pipeline, <table>opts)
<cursor>cursor, <string>error = colobj:aggregate(<array>pipeline, <table>opts)
Performs aggregation operation according to pipeline commands.
Returns document, if opts.explain set to true.
Returns collection object, if pipeline has $out command as last stage.
Returns new cursor object otherwise.

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Cursor methods

Note: you can chain-call property/options functions.

clone

<cursor>new_cursorobj = cursorobj:clone(<bool>explain)
Clones cursor query, optionally setting explain flag.

tailable

<cursor>cursorobj = cursorobj:tailable(<bool>tailable)
Sets relevant query options.

await

<cursor>cursorobj = cursorobj:await(<bool>wait)
Sets relevant query options.

comment

<cursor>cursorobj = cursorobj:comment(<string>comment)
Sets relevant query options.

hint

<cursor>cursorobj = cursorobj:hint(<table>hint)
Sets relevant query options.

max_scan

<cursor>cursorobj = cursorobj:max_scan(<cbson.uint>max_scan)
Sets relevant query options.

max_time_ms

<cursor>cursorobj = cursorobj:max_time_ms(<cbson.uint>max_time_ms)
Sets relevant query options.

read_preference

<cursor>cursorobj = cursorobj:read_preference(<string>read_preference)
Sets relevant query options.

snapshot

<cursor>cursorobj = cursorobj:snapshot(<bool>snapshot)
Sets relevant query options.

sort

<cursor>cursorobj = cursorobj:sort(<table>sort)
Sets query sorting.

skip

<cursor>cursorobj = cursorobj:skip(<cbson.uint>skip)
Sets cursor skip option.

limit

<cursor>cursorobj = cursorobj:limit(<cbson.uint>limit)
Sets cursor limit.

next

<document>doc, <string>error = cursorobj:next()
Returns next document, found by query.

rewind

<cursor>cursorobj = cursorobj:rewind()
Resets cursor position.

all

<array>documents, <string>error = cursorobj:all()
Returns array, containing all documents found by query.

count

<cbsin.uint>number = cursorobj:count()
Returns number of documents, conforming to query.

explain

<document>doc, <string>error = cursorobj:explain()
Returns document with query plan explanation.

distinct

<document>doc, <string>error = cursorobj:distinct(<string>key)
Finds the distinct values for a specified field, according to query.

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GridFS methods

list

<document>doc = gridfsobj:list()
Returns array, containing unique filenames.

remove

<cbson.uint>num, <string>err = gridfsobj:remove(<cbson.oid or self-chosen type>id)
Removes file from GridFS.
Returns number of chunks removed.

find_version

<cbson.oid>id, <string>err = gridfsobj:find_version(<string>name, <number>version)
Find version of file, versions from 0 and upwards point to a specific version,
while version from -1 and downwards point to the most recently added version.
E.g. for file with 3 versions: 0, 1, 2 = -3, -2, -1
0 or -3 is oldest, while -1 or 2 - newest.

open

<gridfs.file>gridfsfile, <string>err = gridfsobj:open(<cbson.oid or self-chosen type>id)
Opens GridFS file for reading.

create

<gridfs.file>gridfsfile = gridfsobj:create(<string>filename, <table>opts, <bool>safe)
Creates new GridFS file for writing.
If safe is true (default), all chunks will be inserted only when you call gridfsfile:close().
If safe is false, chunks will be inserted into db with every gridfsfile:write(...),
last chunk will be inserted on close.
You must call gridfsfile:close(), or you'll end up with orphaned chunks.
Safe mode is good for small files, however, as it stores entire file in memory, it's bad for big files.
Non-safe mode uses maximum of (chunkSize*2-1) bytes for any file.
As a side effect, you can :read() or :slurp() file (except for last chunk).

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GridFS file methods

content_type

<string>val = gridfsfile:content_type()
Returns file content-type.

filename

<string>val = gridfsfile:filename()
Returns file name.

md5

<string>val = gridfsfile:md5()
Returns file checksum

metadata

<document>val = gridfsfile:metadata()
Returns file metadata document.

date

<cbson.date>val = gridfsfile:date()
Returns file upload date.

length

<number>val = gridfsfile:length()
Returns file size.

chunk_size

<number>val = gridfsfile:chunk_size()
Returns file chunk size.

seek

<gridfsfile>gridfsfile = gridfsfile:seek(<number>pos)
Sets offset for reading.

tell

<number>pos = gridfsfile:tell()
Returns current reading position.

read

<string>val, <string>error = gridfsfile:read()
Returns file data from GridFS, starting from current position and until the end of matching chunk.

slurp

<string>val, <string>error = gridfsfile:slurp()
Returns full file contents.

write

<bool>result, <string>error = gridfsfile:write(data)
Writes data to GridFS file.

close

<cbson.oid or self-chosen type>id, <string>error = gridfsfile:close()
Finalizes file by writing queued chunks and metadata.

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Authors

Epifanov Ivan isage.dna@gmail.com

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Sponsors

@dev0pz

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Copyright and License

This module is licensed under the WTFPL license.
(See LICENSE)

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