CODEWITHSUNDEEP
c#listmongodbserialization
user3895837
user3895837

Reputation: 31

How can I search a collection of several list<T> with queries?

I am new to MongoDb so I just played around with it.

Right now I have created a MongoDbCollection<MyDocument> which stores a lot of MyDocuments. MyDocument holds many different parameters like ID, Name, Birthdate, xData, ... 

class MyDocument
{
    public MyDocument() { }

    public ObjectID Id { get; set; }
    public string Name { get; set; }
    public string Birthdate { get; set; }
    public BsonDocument[] xData { get; set; } // just additional data
}

If I query the MongoDbCollection for documents...

MongoCursor elements = collection.Find(Query.And(MyQueryInput));

for example: a query which is looking for name "Peter". I'll get a list with all elements where 'name' equals "peter". It also returns the 'name' field from the "xData" BsonDocument. So far so good everything works as wanted.

Now I want to create a MongoDbCollection<List<MyDocument>>, so its a collection of lists which hold MyDocuments. Thats why I defined a new class which holds the MongoID and a List: 

class MyMongoList
{
    public MyMongoList() { }

    public ObjectID Id() { get; set; }
    public List<MyDocument> list { get; set; }
}

I can add MyDocuments to the list and lists to the collection, but if I loop through nothing happens.

MongoCursor elements = collection.Find(Query.And(MyQueryInput));
foreach(MyMongoList<MyDocument> list in elements)
{
    Console.WriteLine("something"); // nothing happends here
}

I am wondering why "elements" is empty.

[Question] Is it possible to query all lists like above?

[Question] Do I have to add something to the MyMongoList class that MongoDb can search in c#Lists?

At the moment, I do not know what's wrong. I have the feeling that it has to do with MongoDb Serialization but until now I did not find a way to implement it.

Upvotes: 0

Views: 98

Answers (1)

user3895837
user3895837

Reputation: 31

I've found my mistakes. I just have to use the Query.ElemMatch() method. An example was explained here.

to query a list I used the following code:

MongoCursor elements = collection.Find(Query.ElemMatch("list",MyQueryInput));

Now MongoDB puts all lists from the collection, which possess at least 1 MyDokument matching the criterion, into elements.

Upvotes: 1

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