与数组不同的NodeJS Mongodb无法正常工作

Question

Hello try to use an mongodb distinct query with NodeJS (Async). In the GUI of Mongo this query works but in Node it returns the following error

TypeError: db.collection(...).distinct(...).toArray is not a function

The error returns on the following statement:

mongo.connect(uri, function (err, db) {
    console.info('MONGODB START CHECK COLLECTIONS')
    var tasks = [   // Load businessrules
        function (callback) {
            db.collection('businessrules').find({typeBusinessRule: 'SpiderGraphExeption'}).toArray(function (err, businessrules) {
                if (err) return callback(err);
                locals.businessrules = businessrules;
                callback();
            });
        },
        // Load stgOmniTracker
        function (callback) {
            db.collection('stgOmniTracker').find({}).toArray(function (err, tickets) {
                if (err) return callback(err);
                locals.tickets = tickets;
                callback();
            });
        },
        // HERE STARTS THE ERROR
        function (callback) {
            db.collection('stgOmniTracker').distinct("Responsible Group").toArray(function (err, group) {
                if (err) return callback(err);
                locals.group = group;
                callback();
            });
        }
    ];
    console.info('--------------- START ASYNC ------------------------')
    async.parallel(tasks, function (err) {
        if (err) return next(err);
        var businessrules = locals.businessrules, tickets = locals.tickets, resultSet = {}, aggCountsPerDayCattegory = [], group = locals.group
        db.close()
}

I hope you can help me to fix this. Manny Thanks

Erik

Answer 1

db.collection('stgOmniTracker').distinct("Responsible Group", function(err, result)
{
//your code here
});

Answer 2

In the mongodb docs you can see that distinct returns null .

distinct(key[, query][, options], callback)

Arguments:

 key (string) – key to run distinct against. [query] (object) – option query to narrow the returned objects. [options] (object) – additional options during update. callback (function) – this will be called after executing this method. The first parameter will contain the Error object if an error occured, or null otherwise. While the second parameter will contain the results from distinct or null if an error occured. 

**Returns: **

null

It takes a callback as the last argument. In this callback, the second argument contains the results you are looking for.

So your updated code would look like this:

function (callback) {
  db.collection('stgOmniTracker')
    .distinct("Responsible Group", function (err, group) {
        if (err) return callback(err);
        locals.group = group;
        callback();
    });
}