Creation of external objects in function node fails (solved)

I have a problem to understand or to use external modules with new features in the function node.

I tried it first the node-json-db library and then later with the mongodb - npm library.
At least for mongodb I saw that there are nodes available.

However I want to understand why I cannot user external libraries in my function nodes. I always get errors , if I want to create an external object - that it is no constructor.

In general it seems that the definition in the function nodes are correct - as the modules are automatically installed in the users node_modules directory.

image

I defined the external module in the setup tab of the function node:

I always get the error that it is not a constructor to create the object of an external lib .

This happens with more than one lib.
I tried everything and checked settings.js - and as you can see the module itself has been installed.

So here is my settings.js - I recreated it with the new command node-red admin init.

So even if nodes may be already available - it would be nice to understand what is wrong, as I want to use perhaps a nodejs lib in case there is no node available.

I appreciate any help. Here is my settings.js - if this will help to analyse the error:

Zusammenfassung
/**
 * Node-RED Settings created at Sun, 30 Jan 2022 01:27:56 GMT
 *
 * It can contain any valid JavaScript code that will get run when Node-RED
 * is started.
 *
 * Lines that start with // are commented out.
 * Each entry should be separated from the entries above and below by a comma ','
 *
 * For more information about individual settings, refer to the documentation:
 *    https://nodered.org/docs/user-guide/runtime/configuration
 *
 * The settings are split into the following sections:
 *  - Flow File and User Directory Settings
 *  - Security
 *  - Server Settings
 *  - Runtime Settings
 *  - Editor Settings
 *  - Node Settings
 *
 **/

module.exports = {

/*******************************************************************************
 * Flow File and User Directory Settings
 *  - flowFile
 *  - credentialSecret
 *  - flowFilePretty
 *  - userDir
 *  - nodesDir
 ******************************************************************************/

    /** The file containing the flows. If not set, defaults to flows_<hostname>.json **/
    flowFile: "flows.json",

    /** By default, credentials are encrypted in storage using a generated key. To
     * specify your own secret, set the following property.
     * If you want to disable encryption of credentials, set this property to false.
     * Note: once you set this property, do not change it - doing so will prevent
     * node-red from being able to decrypt your existing credentials and they will be
     * lost.
     */
    //credentialSecret: "a-secret-key",

    /** By default, the flow JSON will be formatted over multiple lines making
     * it easier to compare changes when using version control.
     * To disable pretty-printing of the JSON set the following property to false.
     */
    flowFilePretty: true,

    /** By default, all user data is stored in a directory called `.node-red` under
     * the user's home directory. To use a different location, the following
     * property can be used
     */
    //userDir: '/home/nol/.node-red/',

    /** Node-RED scans the `nodes` directory in the userDir to find local node files.
     * The following property can be used to specify an additional directory to scan.
     */
    //nodesDir: '/home/nol/.node-red/nodes',

/*******************************************************************************
 * Security
 *  - adminAuth
 *  - https
 *  - httpsRefreshInterval
 *  - requireHttps
 *  - httpNodeAuth
 *  - httpStaticAuth
 ******************************************************************************/

    /** To password protect the Node-RED editor and admin API, the following
     * property can be used. See http://nodered.org/docs/security.html for details.
     */
    //adminAuth: {
    //    type: "credentials",
    //    users: [{
    //        username: "admin",
    //        password: "$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN.",
    //        permissions: "*"
    //    }]
    //},
    
    /** The following property can be used to enable HTTPS
     * This property can be either an object, containing both a (private) key
     * and a (public) certificate, or a function that returns such an object.
     * See http://nodejs.org/api/https.html#https_https_createserver_options_requestlistener
     * for details of its contents.
     */

    /** Option 1: static object */
    //https: {
    //  key: require("fs").readFileSync('privkey.pem'),
    //  cert: require("fs").readFileSync('cert.pem')
    //},

    /** Option 2: function that returns the HTTP configuration object */
    // https: function() {
    //     // This function should return the options object, or a Promise
    //     // that resolves to the options object
    //     return {
    //         key: require("fs").readFileSync('privkey.pem'),
    //         cert: require("fs").readFileSync('cert.pem')
    //     }
    // },

    /** If the `https` setting is a function, the following setting can be used
     * to set how often, in hours, the function will be called. That can be used
     * to refresh any certificates.
     */
    //httpsRefreshInterval : 12,

    /** The following property can be used to cause insecure HTTP connections to
     * be redirected to HTTPS.
     */
    //requireHttps: true,

    /** To password protect the node-defined HTTP endpoints (httpNodeRoot),
     * including node-red-dashboard, or the static content (httpStatic), the
     * following properties can be used.
     * The `pass` field is a bcrypt hash of the password.
     * See http://nodered.org/docs/security.html#generating-the-password-hash
     */
    //httpNodeAuth: {user:"user",pass:"$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN."},
    //httpStaticAuth: {user:"user",pass:"$2a$08$zZWtXTja0fB1pzD4sHCMyOCMYz2Z6dNbM6tl8sJogENOMcxWV9DN."},

/*******************************************************************************
 * Server Settings
 *  - uiPort
 *  - uiHost
 *  - apiMaxLength
 *  - httpServerOptions
 *  - httpAdminRoot
 *  - httpAdminMiddleware
 *  - httpNodeRoot
 *  - httpNodeCors
 *  - httpNodeMiddleware
 *  - httpStatic
 ******************************************************************************/

    /** the tcp port that the Node-RED web server is listening on */
    uiPort: process.env.PORT || 1880,

    /** By default, the Node-RED UI accepts connections on all IPv4 interfaces.
     * To listen on all IPv6 addresses, set uiHost to "::",
     * The following property can be used to listen on a specific interface. For
     * example, the following would only allow connections from the local machine.
     */
    //uiHost: "127.0.0.1",

    /** The maximum size of HTTP request that will be accepted by the runtime api.
     * Default: 5mb
     */
    //apiMaxLength: '5mb',

    /** The following property can be used to pass custom options to the Express.js
     * server used by Node-RED. For a full list of available options, refer
     * to http://expressjs.com/en/api.html#app.settings.table
     */
    //httpServerOptions: { },

    /** By default, the Node-RED UI is available at http://localhost:1880/
     * The following property can be used to specify a different root path.
     * If set to false, this is disabled.
     */
    //httpAdminRoot: '/admin',

    /** The following property can be used to add a custom middleware function
     * in front of all admin http routes. For example, to set custom http
     * headers. It can be a single function or an array of middleware functions.
     */
    // httpAdminMiddleware: function(req,res,next) {
    //    // Set the X-Frame-Options header to limit where the editor
    //    // can be embedded
    //    //res.set('X-Frame-Options', 'sameorigin');
    //    next();
    // },


    /** Some nodes, such as HTTP In, can be used to listen for incoming http requests.
     * By default, these are served relative to '/'. The following property
     * can be used to specifiy a different root path. If set to false, this is
     * disabled.
     */
    //httpNodeRoot: '/red-nodes',

    /** The following property can be used to configure cross-origin resource sharing
     * in the HTTP nodes.
     * See https://github.com/troygoode/node-cors#configuration-options for
     * details on its contents. The following is a basic permissive set of options:
     */
    //httpNodeCors: {
    //    origin: "*",
    //    methods: "GET,PUT,POST,DELETE"
    //},

    /** If you need to set an http proxy please set an environment variable
     * called http_proxy (or HTTP_PROXY) outside of Node-RED in the operating system.
     * For example - http_proxy=http://myproxy.com:8080
     * (Setting it here will have no effect)
     * You may also specify no_proxy (or NO_PROXY) to supply a comma separated
     * list of domains to not proxy, eg - no_proxy=.acme.co,.acme.co.uk
     */

    /** The following property can be used to add a custom middleware function
     * in front of all http in nodes. This allows custom authentication to be
     * applied to all http in nodes, or any other sort of common request processing.
     * It can be a single function or an array of middleware functions.
     */
    //httpNodeMiddleware: function(req,res,next) {
    //    // Handle/reject the request, or pass it on to the http in node by calling next();
    //    // Optionally skip our rawBodyParser by setting this to true;
    //    //req.skipRawBodyParser = true;
    //    next();
    //},

    /** When httpAdminRoot is used to move the UI to a different root path, the
     * following property can be used to identify a directory of static content
     * that should be served at http://localhost:1880/.
     */
    //httpStatic: '/home/nol/node-red-static/',

/*******************************************************************************
 * Runtime Settings
 *  - lang
 *  - logging
 *  - contextStorage
 *  - exportGlobalContextKeys
 *  - externalModules
 ******************************************************************************/

     /** Uncomment the following to run node-red in your preferred language.
      * Available languages include: en-US (default), ja, de, zh-CN, zh-TW, ru, ko
      * Some languages are more complete than others.
      */
     // lang: "de",

     /** Configure the logging output */
     logging: {
         /** Only console logging is currently supported */
         console: {
             /** Level of logging to be recorded. Options are:
              * fatal - only those errors which make the application unusable should be recorded
              * error - record errors which are deemed fatal for a particular request + fatal errors
              * warn - record problems which are non fatal + errors + fatal errors
              * info - record information about the general running of the application + warn + error + fatal errors
              * debug - record information which is more verbose than info + info + warn + error + fatal errors
              * trace - record very detailed logging + debug + info + warn + error + fatal errors
              * off - turn off all logging (doesn't affect metrics or audit)
              */
             level: "info",
             /** Whether or not to include metric events in the log output */
             metrics: false,
             /** Whether or not to include audit events in the log output */
             audit: false
         }
     },

     /** Context Storage
      * The following property can be used to enable context storage. The configuration
      * provided here will enable file-based context that flushes to disk every 30 seconds.
      * Refer to the documentation for further options: https://nodered.org/docs/api/context/
      */
     //contextStorage: {
     //    default: {
     //        module:"localfilesystem"
     //    },
     //},

     /** `global.keys()` returns a list of all properties set in global context.
      * This allows them to be displayed in the Context Sidebar within the editor.
      * In some circumstances it is not desirable to expose them to the editor. The
      * following property can be used to hide any property set in `functionGlobalContext`
      * from being list by `global.keys()`.
      * By default, the property is set to false to avoid accidental exposure of
      * their values. Setting this to true will cause the keys to be listed.
      */
     exportGlobalContextKeys: false,

     /** Configure how the runtime will handle external npm modules.
      * This covers:
      *  - whether the editor will allow new node modules to be installed
      *  - whether nodes, such as the Function node are allowed to have their
      * own dynamically configured dependencies.
      * The allow/denyList options can be used to limit what modules the runtime
      * will install/load. It can use '*' as a wildcard that matches anything.
      */
     externalModules: {
         // autoInstall: false,   /** Whether the runtime will attempt to automatically install missing modules */
         // autoInstallRetry: 30, /** Interval, in seconds, between reinstall attempts */
         // palette: {              /** Configuration for the Palette Manager */
         //     allowInstall: true, /** Enable the Palette Manager in the editor */
         //     allowUpload: true,  /** Allow module tgz files to be uploaded and installed */
         //     allowList: [],
         //     denyList: []
         // },
         // modules: {              /** Configuration for node-specified modules */
         //     allowInstall: true,
         //     allowList: [],
         //     denyList: []
         // }
     },


/*******************************************************************************
 * Editor Settings
 *  - disableEditor
 *  - editorTheme
 ******************************************************************************/

    /** The following property can be used to disable the editor. The admin API
     * is not affected by this option. To disable both the editor and the admin
     * API, use either the httpRoot or httpAdminRoot properties
     */
    //disableEditor: false,

    /** Customising the editor
     * See https://nodered.org/docs/user-guide/runtime/configuration#editor-themes
     * for all available options.
     */
    editorTheme: {
        /** The following property can be used to set a custom theme for the editor.
         * See https://github.com/node-red-contrib-themes/theme-collection for
         * a collection of themes to chose from.
         */
        //theme: "",
        palette: {
            /** The following property can be used to order the categories in the editor
             * palette. If a node's category is not in the list, the category will get
             * added to the end of the palette.
             * If not set, the following default order is used:
             */
            //categories: ['subflows', 'common', 'function', 'network', 'sequence', 'parser', 'storage'],
        },
        projects: {
            /** To enable the Projects feature, set this value to true */
            enabled: false,
            workflow: {
                /** Set the default projects workflow mode.
                 *  - manual - you must manually commit changes
                 *  - auto - changes are automatically committed
                 * This can be overridden per-user from the 'Git config'
                 * section of 'User Settings' within the editor
                 */
                mode: "manual"
            }
        },
        codeEditor: {
            /** Select the text editor component used by the editor.
             * Defaults to "ace", but can be set to "ace" or "monaco"
             */
            lib: "monaco",
            options: {
                /** The follow options only apply if the editor is set to "monaco"
                 *
                 * theme - must match the file name of a theme in
                 * packages/node_modules/@node-red/editor-client/src/vendor/monaco/dist/theme
                 * e.g. "tomorrow-night", "upstream-sunburst", "github", "my-theme"
                 */
                theme: "vs",
                /** other overrides can be set e.g. fontSize, fontFamily, fontLigatures etc.
                 * for the full list, see https://microsoft.github.io/monaco-editor/api/interfaces/monaco.editor.istandaloneeditorconstructionoptions.html
                 */
                //fontSize: 14,
                //fontFamily: "Cascadia Code, Fira Code, Consolas, 'Courier New', monospace",
                //fontLigatures: true,
            }
        }
    },

/*******************************************************************************
 * Node Settings
 *  - fileWorkingDirectory
 *  - functionGlobalContext
 *  - functionExternalModules
 *  - nodeMessageBufferMaxLength
 *  - ui (for use with Node-RED Dashboard)
 *  - debugUseColors
 *  - debugMaxLength
 *  - execMaxBufferSize
 *  - httpRequestTimeout
 *  - mqttReconnectTime
 *  - serialReconnectTime
 *  - socketReconnectTime
 *  - socketTimeout
 *  - tcpMsgQueueSize
 *  - inboundWebSocketTimeout
 *  - tlsConfigDisableLocalFiles
 *  - webSocketNodeVerifyClient
 ******************************************************************************/

    /** The working directory to handle relative file paths from within the File nodes
     * defaults to the working directory of the Node-RED process.
     */
    //fileWorkingDirectory: "",

    /** Allow the Function node to load additional npm modules directly */
    functionExternalModules: true,

    /** The following property can be used to set predefined values in Global Context.
     * This allows extra node modules to be made available with in Function node.
     * For example, the following:
     *    functionGlobalContext: { os:require('os') }
     * will allow the `os` module to be accessed in a Function node using:
     *    global.get("os")
     */
    functionGlobalContext: {
        // os:require('os'),
    },

    /** The maximum number of messages nodes will buffer internally as part of their
     * operation. This applies across a range of nodes that operate on message sequences.
     * defaults to no limit. A value of 0 also means no limit is applied.
     */
    //nodeMessageBufferMaxLength: 0,

    /** If you installed the optional node-red-dashboard you can set it's path
     * relative to httpNodeRoot
     * Other optional properties include
     *  readOnly:{boolean},
     *  middleware:{function or array}, (req,res,next) - http middleware
     *  ioMiddleware:{function or array}, (socket,next) - socket.io middleware
     */
    //ui: { path: "ui" },

    /** Colourise the console output of the debug node */
    //debugUseColors: true,

    /** The maximum length, in characters, of any message sent to the debug sidebar tab */
    debugMaxLength: 1000,

    /** Maximum buffer size for the exec node. Defaults to 10Mb */
    //execMaxBufferSize: 10000000,

    /** Timeout in milliseconds for HTTP request connections. Defaults to 120s */
    //httpRequestTimeout: 120000,

    /** Retry time in milliseconds for MQTT connections */
    mqttReconnectTime: 15000,

    /** Retry time in milliseconds for Serial port connections */
    serialReconnectTime: 15000,

    /** Retry time in milliseconds for TCP socket connections */
    //socketReconnectTime: 10000,

    /** Timeout in milliseconds for TCP server socket connections. Defaults to no timeout */
    //socketTimeout: 120000,

    /** Maximum number of messages to wait in queue while attempting to connect to TCP socket
     * defaults to 1000
     */
    //tcpMsgQueueSize: 2000,

    /** Timeout in milliseconds for inbound WebSocket connections that do not
     * match any configured node. Defaults to 5000
     */
    //inboundWebSocketTimeout: 5000,

    /** To disable the option for using local files for storing keys and
     * certificates in the TLS configuration node, set this to true.
     */
    //tlsConfigDisableLocalFiles: true,

    /** The following property can be used to verify websocket connection attempts.
     * This allows, for example, the HTTP request headers to be checked to ensure
     * they include valid authentication information.
     */
    //webSocketNodeVerifyClient: function(info) {
    //    /** 'info' has three properties:
    //    *   - origin : the value in the Origin header
    //    *   - req : the HTTP request
    //    *   - secure : true if req.connection.authorized or req.connection.encrypted is set
    //    *
    //    * The function should return true if the connection should be accepted, false otherwise.
    //    *
    //    * Alternatively, if this function is defined to accept a second argument, callback,
    //    * it can be used to verify the client asynchronously.
    //    * The callback takes three arguments:
    //    *   - result : boolean, whether to accept the connection or not
    //    *   - code : if result is false, the HTTP error status to return
    //    *   - reason: if result is false, the HTTP reason string to return
    //    */
    //},
}

Enabling options in the externalModules object will not solve the problem. I hope someone can help me to understand the problem.

Untested but try this:
Change it to import as "mongodb". Then add the line

const  MongoClient  = mongodb.MongoClient;

at the top of your function.

Personally I just use node-red-node-mongodb

2 Likes
const { MongoClient } = mongodb;
// Replace the uri string with your MongoDB deployment's connection string.
const uri = "mongodb://localhost:27017";

const client = new MongoClient(uri);

async function run() {
  try {
    await client.connect();
    const database = client.db('nodered');  // db name
    const temperatures = database.collection('temperatures'); // collection name
    
    const query = {  };  // any 
    const result = await temperatures.findOne(query);  // findOne Document
    node.send({payload: result});
  } finally {
    // Ensures that the client will close when you finish/error
    await client.close();
  }
}
run().catch(console.dir);
1 Like

Wow - thank you very much - it seems that is working.

const MongoClient = mongodb.MongoClient;
const client = new MongoClient(url);

so more or less - I missed only this line:

const MongoClient = mongodb.MongoClient;

I try it with the other lib - and I am not sure - if I understand what this line really does. :slight_smile: But I am happy that it works in general. Many thanks!

I believe it is "destructuring", you can read more here: Destructuring Nested Objects. I love destructuring. However, as I use… | by Ronald Chen | Medium

1 Like

Ok - I think more or less - it is just to access the exported property or object of or within the library.

What I begin to understand is, that the name of the variable in the Setup Tab contains the library in total and then I need to address the exported function or object.

so my access is also working now.

Then this code is also working:

const JsonDB = nodeJsonDb.JsonDB;
const Config = nodeJsonDbDistLibJsonDBConfig.Config;

var db = new JsonDB(new Config("myDataBase", true, true, '/'));

db.push('/test1','super test');

and myDataBase.json looks great:

{
    "test1": "super test"
}

So many thanks - I guess - I understand a little bit more. :slight_smile:

Great support - here. :+1: :+1: :+1:

Yes - I saw this node as well - and I will use it. But I wanted to understand in general, why I couldn't create objects of an external library. It is not so easy to get sometimes the small things which are normal for the professionals - even if I spent plenty of times in google. :wink:

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