creating custom components and running with NoFlo - mongodb

Question

I am creating a custom component which interfaces with MongoDB. I wrote a CoffeeScript file which just connects to MongoDB, and stored it at noflo/components folder.
MongoBase.coffee
noflo = require "noflo"
mongodb = require "mongodb"
url = require "url"
class exports.MongoBase extends noflo.Component
constructor: ->
super
#inPorts =
url: new noflo.Port()
#inPorts.url.on "data", (data) =>
try
#parseConnectionString(data)
#MongoClient = mongodb.MongoClient;
#MongoClient.connect #serverUrl, (err, db) ->
if err
console.log("Error in connecting to MongoDB")
else
console.log("Connected to MongoDB")
catch error
console.log(error)
parseConnectionString: (connectionString) =>
databaseUrl = try
url.parse(connectionString)
catch error
console.log(error)
[..., #serverUrl, #databaseName] = databaseUrl.split('/')
#serverUrl = "mongo://" + #serverUrl
I added the following entry to component.json
"MongoBase": "components/MongoBase.coffee"
In addition to this, I created a mongo.fbp file to check the flow of the component. The FBP file has the following code:
'mongodb://localhost:27017/test' -> url DocReader(MongoBase)
On running noflo mongo.fbp, I get the following error:
/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:1628
edges.forEach(function (o, i) {
^
TypeError: Object #<Object> has no method 'forEach'
at Object.parser.registerEdges (/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:1628:15)
at peg$c25 (/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:60:50)
at peg$parseline (/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:749:30)
at peg$parsestart (/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:282:12)
at Object.parse (/home/saurabh/workspace/noflo/node_modules/fbp/lib/fbp.js:1650:18)
at Object.exports.loadFBP (/home/saurabh/workspace/noflo/lib/Graph.js:1065:33)
at /home/saurabh/workspace/noflo/lib/Graph.js:1116:24
at fs.js:268:14
at Object.oncomplete (fs.js:107:15)
Is there something wrong with my code, or the steps I am using to run the code?

Answer 1

You may have figured this out already, as it's been several month's since you asked, but I believe you need to add the getComponent() method to your class before you export it.
noflo = require "noflo"
mongodb = require "mongodb"
url = require "url"
class MongoBase extends noflo.Component
constructor: ->
super
#inPorts =
url: new noflo.Port()
#inPorts.url.on "data", (data) =>
try
#parseConnectionString(data)
#MongoClient = mongodb.MongoClient;
#MongoClient.connect #serverUrl, (err, db) ->
if err
console.log("Error in connecting to MongoDB")
else
console.log("Connected to MongoDB")
catch error
console.log(error)
parseConnectionString: (connectionString) =>
databaseUrl = try
url.parse(connectionString)
catch error
console.log(error)
[..., #serverUrl, #databaseName] = databaseUrl.split('/')
#serverUrl = "mongo://" + #serverUrl
MongoBase.getComponent = -> new MongoBase
exports.MongoBase = MongoBase
Additionally, in your graph for the component loader to work you need to specify the package your component lives in. If your package.json/component.json have a name entry like "name": "mongo-base" then you'd have to specify this in the FBP graph, like so:
'mongodb://localhost:27017/test' -> url DocReader(mongo-base/MongoBase)
N.B.: The loader clobbers any instances of 'noflo-' in the package name, so this needs to be taken into account. E.g. the name 'noflo-mongo' would get turned into just 'mongo', so when invoking the package's components you'd write in the fbp DocReader(mongo/MongoBase) and not DocReader(noflo-mongo/MongoBase).