undefined is not a function while writing a promise function in Nodejs

Question

I am trying to write a function of mine using Bluebird promise Library. I promisified the ldap-js the createClient function of ldap-js by:

    var Promise= require('bluebird'); //done at the beginning
        var createClientAsync = Promise.promisify(require('ldapjs').createClient);
getUser:function(user) {
    var memberRoles = [];
    var searchFilter = '(&(member='+user.dn+'))';
     var opts = {
           filter: searchFilter,
           scope: 'sub',
           attributes: ['dn']
         };

    createClientAsync({
           url: 'ldap://x.x.x.x:3889'
         })
         .then(function(client){
           return client.search('o=pic', opts);
         })
         .then(function(res) {
           res.on('searchEntry', function(entry) {
               console.log('entry: ' + JSON.stringify(entry.object));
               for (var role in roles) {
                 var mapping = roles[role];
                 if (mapping.group === entry.object.dn) {
                   memberRoles.push(role);
                 }
               }
             });
         })
         .then(function() {
             return memberRoles;
         });
}

I get an error at createClientAsync undefined is not a function.

@VsevolodGoloviznin yes. I did Promise= require('bluebird'); — user1692342, Nov 14 '16 at 19:40
@VsevolodGoloviznin I think the problem is since the functions are returning emitter functions, like .on — user1692342, Nov 14 '16 at 20:29
getUser returns `undefined` due to it not having a return value anywhere - even if you fixed that, the promise chain would resolve to an empty array because the second last .then wont have pushed anything into memberRoles before the final .then returns memberRoles ... — Jaromanda X, Nov 14 '16 at 22:07
@Jaromanda X yes I figured out why it is happening, but I am not able to understand how do i resolve this, since there are emitter functions involved. The event searchEntry is usually called 3 times for me and once that is done I want to return — user1692342, Nov 14 '16 at 22:25
@user1692342, is there an "emitter function" when `res` is "done"? — Jaromanda X, Nov 14 '16 at 22:32

score 0 · Answer 1 · answered Nov 14 '16 at 22:38

After a brief reading of the ldapjs documentation, I can suggest the following code

getUser:function(user) {
    var searchFilter = '(&(member='+user.dn+'))';
    var opts = {
        filter: searchFilter,
        scope: 'sub',
        attributes: ['dn']
    };
    return createClientAsync({
        url: 'ldap://x.x.x.x:3889'
    })
    .then(function(client){
        return client.search('o=pic', opts);
    })
    .then(function(res) {
        var memberRoles = [];
        return new Promise(function(resolve, reject) {
            res.on('searchEntry', function(entry) {
                console.log('entry: ' + JSON.stringify(entry.object));
                for (var role in roles) {
                    var mapping = roles[role];
                    if (mapping.group === entry.object.dn) {
                        memberRoles.push(role);
                    }
                }
            });
            res.on('end', function() {
                resolve(memberRoles);
            });
        });
    });
}

note the "new Promise" and res.on('end' to resolve the promise once the "search" has completed

as I said, brief reading of documentation, so this may be completely invalid :p

Probably the [`for…in` enuration should be a proper array iteration](http://stackoverflow.com/q/500504/1048572) — Bergi, Nov 14 '16 at 23:28
@JaromandaX Thanks, I will check it out and update. Currently I am calling, getUser in the following manner: user.roles = this.getUser(user); this.xyz(user,'test').then(function(res) { .. }).catch(function(e) { .. }); Will the function xyz get executed before getUser is completed or do I need to chain these promises together, like: this.getUser(user) .then(function(res) { user.roles = res; }).then(this.xyz ) and so on ? — user1692342, Nov 15 '16 at 00:10
if you want to wait for getUser to "complete" before executing this.xyz, then, yes, you need to chain it — Jaromanda X, Nov 15 '16 at 00:12

undefined is not a function while writing a promise function in Nodejs

1 Answers1