C#•2y ago

❔ Hello I am new to C#, I dont understand this error:

I have a insert method that adds to queue:

_insertQueue.Enqueue(new object[] { database, collection, document });

_insertQueue.Enqueue(new object[] { database, collection, document });

and then in a thread loop:

while(_insertQueue.Count > 0)
                {
                    var items = _insertQueue.Dequeue();
                    var database = items[0];
                    var collection = items[1];
                    var document = items[2];
                    var db = _mongoClient.GetDatabase(database);
                    var col = db.GetCollection<BsonDocument>(collection);
                    col.InsertOne(document);
                }

while(_insertQueue.Count > 0)
                {
                    var items = _insertQueue.Dequeue();
                    var database = items[0];
                    var collection = items[1];
                    var document = items[2];
                    var db = _mongoClient.GetDatabase(database);
                    var col = db.GetCollection<BsonDocument>(collection);
                    col.InsertOne(document);
                }

but I'm getting this error:

error CS0021: Cannot apply indexing with [] to an expression of type 'object'

error CS0021: Cannot apply indexing with [] to an expression of type 'object'

35 Replies

SherafOP•2y ago

So im trying to cast items as a list but I can't figure it out Ok this seem to work:

while(_insertQueue.Count > 0)
                {
                    var items = (ArrayList)_insertQueue.Dequeue();
                    string database = (string)items[0];
                    string collection = (string)items[1];
                    BsonDocument document = (BsonDocument)items[2];
                    var db = _mongoClient.GetDatabase(database);
                    var col = db.GetCollection<BsonDocument>(collection);
                    col.InsertOne(document);
                }

while(_insertQueue.Count > 0)
                {
                    var items = (ArrayList)_insertQueue.Dequeue();
                    string database = (string)items[0];
                    string collection = (string)items[1];
                    BsonDocument document = (BsonDocument)items[2];
                    var db = _mongoClient.GetDatabase(database);
                    var col = db.GetCollection<BsonDocument>(collection);
                    col.InsertOne(document);
                }

is that the right way?

Pobiega•2y ago

What is your _insertQueue declared as? Never use ArrayList

SherafOP•2y ago

private Queue _insertQueue = new Queue(); Error: Specified cast is not valid.

Pobiega•2y ago

yeah its an untyped queue

circles.png•2y ago

dont cast to arraylist

Pobiega•2y ago

you need to use the generic version Queue<object[]>

SherafOP•2y ago

SherafOP•2y ago

Not letting me ok

Pobiega•2y ago

you need to update your imports ^

SherafOP•2y ago

private Queue<object[]> _insertQueue = new Queue<string, string, BsonDocument>(); I added the import

circles.png•2y ago

wrong type argument should be object[] right

Pobiega•2y ago

you can't have type argument mismatches also, I dont think queue takes 3 type arguments which is why Diddy suggested a tuple (T1, T2, T3) or a custom class

SherafOP•2y ago

private Queue<(string, string, BsonDocument)> _insertQueue = new Queue<(string, string, BsonDocument)>(); this makes sense?

Pobiega•2y ago

sure I'd probably use a record myself, but this is fine

SherafOP•2y ago

and then :

public void Insert(string database, string collection, BsonDocument document)
        {
            _insertQueue.Enqueue((database, collection, document));
        }

public void Insert(string database, string collection, BsonDocument document)
        {
            _insertQueue.Enqueue((database, collection, document));
        }

Pobiega•2y ago

yeah, seems okay at a glance

SherafOP•2y ago

this

SherafOP•2y ago

Pobiega•2y ago

you can't access it with an index accesser

circles.png•2y ago

unpack the tuple

SherafOP•2y ago

var (database, collection, document) = _insertQueue.Dequeue(); ?

circles.png•2y ago

var database, collection, document = items or inline that

SherafOP•2y ago

Not used to all these types, I come from python :x

circles.png•2y ago

same, but a long time ago

Pobiega•2y ago

time to unlearn your bad habits 🙂

SherafOP•2y ago

I kinda like it tho, i feel like it makes things more clear or forces you to write clean code

circles.png•2y ago

it is definitely safer (harder to write bugs)

Pobiega•2y ago

the good thing with types is that after some time, you revisit this code, you don't need to go "uhh, what the hell do I actually write to that queue.. let me look" you can just look at the type declaration oh, its a (string database, string collection, BsonDocument document)

Unknown User•2y ago

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SherafOP•2y ago

No clue i just started using mongo and csharp

Unknown User•2y ago

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SherafOP•2y ago

Yeah i should grab the database and the collection before the loop obviously This is pure testing at this point

Unknown User•2y ago

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SherafOP•2y ago

Thanks for the help guys!

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Hello I am new to C#, I dont understand this error: