Name

lua-resty-mongol - Lua Mongodb driver for ngx_lua base on the cosocket API

Thanks to project Mongol by daurnimator

Dependencies

luajit(or attempt to yield across metamethod/C-call boundary error will be produced.)

ngx_lua 0.5.0rc5 or ngx_openresty 1.0.11.7 is required.

Installation

	make install

Usage

Add package path into nginx.conf.

    lua_package_path '/usr/local/openresty/lualib/?/init.lua;;';

or into lua files before requiring.

    local p = "/usr/local/openresty/lualib/"
    local m_package_path = package.path
    package.path = string.format("%s?.lua;%s?/init.lua;%s",
        p, p, m_package_path)

Requring the module will return a function that connects to mongod: it takes a host (default localhost) and a port (default 27017); it returns a connection object.

	mongol = require "resty.mongol"
	conn = mongol:new() -- return a conntion object

###Connection objects have server wide methods.

####ok,err = conn:connect(host, port) Default host and port is: localhost and 27017.

####ok,err = conn:set_timeout(msec) Sets socket connecting, reading, writing timeout value, unit is milliseconds.

In case of success, returns 1. In case of errors, returns nil with a string describing the error.

####ok,err = conn:set_keepalive(msec, pool_size) Keeps the socket alive for msec by ngx_lua cosocket.

In case of success, returns 1. In case of errors, returns nil with a string describing the error.

####times,err = conn:get_reused_times() Returns the socket reused times.

In case of success, returns times. In case of errors, returns nil with a string describing the error.

####ok,err = conn:close() Closes the connection.

In case of success, returns 1. In case of errors, returns nil with a string describing the error.

####bool, hosts = conn:ismaster() Returns a boolean indicating if this is the master server and a table of other hosts this server is replicating with or nil, err on failure.

####newconn = conn:getprimary ( [already_checked] ) Returns a new connection object that is connected to the primary server or nil , errmsg on failure.

The returned connection object may be this connection object itself.

####databases = conn:databases ( ) Returns a table describing databases on the server.

	databases.name: string
	databases.empty: boolean
	databases.sizeOnDisk: number

####conn:shutdown() Shutsdown the server. Returns nothing.

####db = conn:new_db_handle(database_name) Returns a database object, or nil.

###Database objects perform actions on a database

####db:list()

####db:dropDatabase()

####db:add_user(username, password)

####ok, err = db:auth(username, password) Returns 1 in case of success, or nil with error message.

####col = db:get_col(collection_name) Returns a collection object for more operations.

####gridfs = db:get_gridfs(fs)

###Collection objects

####n = col:count(query)

####ok, err = col:drop() Returns 1 in case of success, or nil with error message.

####n, err = col:update(selector, update, upsert, multiupdate, safe) Returns number of rows been updated or nil for error.

• upsert, if set to 1, the database will insert the supplied object into the collection if no matching document is found, default to 0.
• multiupdate, if set to 1, the database will update all matching objects in the collection. Otherwise only updates first matching doc, default to 0. Multi update only works with $ operators.
• safe can be a boolean or integer, defaults to 0. If 1, the program will issue a cmd getlasterror to server to query the result. If false, return value n would always be -1

####n, err = col:insert(docs, continue_on_error, safe) Returns 0 for success, or nil with error message.

• continue_on_error, if set, the database will not stop processing a bulk insert if one fails (eg due to duplicate IDs).
• safe can be a boolean or integer, defaults to 0 or false. If 1 or ``true, the program will issue a cmd getlasterror` to server to query the result. If `false`, return value `n` would always be `-1`

####n, err = col:delete(selector, singleRemove, safe) Returns number of rows been deleted, or nil with error message.

• singleRemove if set to 1, the database will remove only the first matching document in the collection. Otherwise all matching documents will be removed. Default to 0
• safe can be a boolean or integer, defaults to 0. If 1, the program will issue a cmd getlasterror to server to query the result. If false, return value n would always be -1

####r = col:find_one(query, returnfields) Returns a single element array, or nil.

• returnfields is the fields to return, eg: {n=0} or {n=1}

####cursor = col:find(query, returnfields, num_each_query) Returns a cursor object for excuting query.

• returnfields is the fields to return, eg: {n=0} or {n=1}
• num_each_query is the max result number for each query of the cursor to avoid fetch a large result in memory, must larger than 1, 0 for no limit, default to 100.

####col:getmore(cursorID, [numberToReturn], [offset_i])

• cursorID is an 8 byte string representing the cursor to getmore on
• numberToReturn is the number of results to return, defaults to -1
• offset_i is the number to start numbering the returned table from, defaults to 1

####col:kill_cursors(cursorIDs)

###Cursor objects

####index, item = cursor:next() Returns the next item and advances the cursor.

####cursor:pairs() A handy wrapper around cursor:next() that works in a generic for loop:

	for index, item in cursor:pairs() do

####cursor:limit(n) Limits the number of results returned.

####result = cursor:sort(field, size) Returns an array with size size sorted by given field.

• field is an array by which to sort, and this array size MUST be 1. The element in the array has as key the field name, and as value either 1 for ascending sort, or -1 for descending sort.
• num is the temp array size for sorting, default to 10000.

###Object id

####objid:tostring() ####objid:get_ts() ####objid:get_pid() ####objid:get_hostname() ####objid:get_inc()

###Grid FS Object

under developing

####gridfs_file = gridfs:find_one(fields) Returns a gridfs file object.

####gridfs_file = gridfs:remove(fields, continue_on_err, safe) Returns number of files been deleted, or nil with error message.

• singleRemove if set to 1, the database will remove only the first matching document in the collection. Otherwise all matching documents will be removed. Default to 0
• safe can be a boolean or integer, defaults to 0. If 1, the program will issue a cmd getlasterror to server to query the result. If false, return value n would always be -1

####bool = gridfs:get(file_handler, fields) Writes first object matchs fields into file_handler. This API will malloc a buffer in file size in memory.

####n, err = gridfs:insert(file_handler, meta, safe) Returns 0 for success, or nil with error message.

• file_handler is file handler returned by io:open().
• meta is a table include _id, filename, chunkSize, contentType, aliases, metadata or anything the user wants to store. Default meta.filename is the object id in string.
• safe can be a boolean or integer, defaults to 0. If 1, the program will issue a cmd getlasterror to server to query the result. If false, return value n would always be -1

####gridfs_file, err = gridfs:new(meta) Returns a new gridfs file object, or nil with error message.

• meta is a table include _id, filename, chunkSize, contentType, aliases, metadata or anything the user wants to store. Default meta.filename is the object id in string.

###Grid FS File Object

####n, err = gridfs_file:read(size, offset) Returns number of bytes read from mongodb, or nil with error message.

• offse start from 0

####n, err = gridfs_file:write(buf, offset, size) Returns number of bytes writen into mongodb, or nil with error message.

• offset is the file offset(should not beyond the end of the file), starting from 0.
• size is the number of bytes to be writen.

####bool, err = gridfs_file:update_md5() Hashs the file content and updates the md5 in file collection.

Notes

• collections are string containing any value except "\0"
• database_name are strings containing any character except "." and "\0"

Known Issues

1. Auth bson message has reduntant value.
2. Could not inserting a null array, it always inserted as a document.
3. Gridfs_new api only create a meta info in file_col.

Example

        local mongo = require "resty.mongol"
        conn = mongo:new()
        conn:set_timeout(1000)
        ok, err = conn:connect()
        if not ok then
            ngx.say("connect failed: "..err)
        end

        local db = conn:new_db_handle ( "test" )
        col = db:get_col("test")

        r = col:find_one({name="dog"})
        ngx.say(r["name"])

For Test Case

#####mongo config: > config = {_id: 'testset', members: [ {_id: 0, host: '10.6.2.51:27017'}, {_id: 1, host: '10.6.2.51:27018'}, {_id: 2, host: '10.6.2.51:27019'}] } > rs.initiate(config);

#####start-mongo.sh: nohup bin/mongod --dbpath=/data/57cbd36d-5b70-4888-8537-bea71119363e/mongodb --oplogSize 10 --rest --replSet testset --port 27017 --keyFile key.file & nohup bin/mongod --dbpath=/data/0a9419ae-4ec3-48c2-ad8d-df68a09aed13/mongodb --oplogSize 10 --rest --replSet testset --port 27018 --keyFile key.file & nohup bin/mongod --dbpath=/data/8ee9efc0-a854-4c45-8893-7b4cb9ed0e5f/mongodb --oplogSize 10 --rest --replSet testset --port 27019 --keyFile key.file &

#####mongo user: > use test > db.addUser("admin","admin")