How to build a conditional query in MongoDB C#

Question

I am having trouble building a conditional query using C# MongoDB driver. Whenever I run the code below, I get an empty list. Any help will be greatly appreciated.

Here is my function

 public async void searchBook()
 {
        Book book = new Book();

        IMongoDatabase mdb = MongoDBConnectionManager.ConnectToMongoDB();

        var query = new BsonDocument();            

        if (queryString.ContainsKey("Title"))
        {
            query.Add("Title", queryString["Title"]);
        }

        if (queryString.ContainsKey("ISBN"))
        {
            query.Add("Isbn", queryString["ISBN"]);
        }

        if (queryString.ContainsKey("Author"))
        {
            query.Add("Author", queryString["Author"]);
        }

        if (queryString.ContainsKey("Publisher"))
        {
            query.Add("Publisher", queryString["Publisher"]);
        }

        var collection = mdb.GetCollection<Book>("Book");

        var sort = Builders<Book>.Sort.Ascending("Title");

        if(query.ElementCount > 0)
        {
            var list = await collection.Find(query).Sort(sort).ToListAsync();
            dt = ConvertToDataTable(list);
            BindGridView(dt);
        }
        else
        {
            var list = await collection.Find(Builders<Book>.Filter.Empty).Sort(sort).ToListAsync();
            dt = ConvertToDataTable(list);
            BindGridView(dt);
        }                                
    }

what happens when you actually step through the code using the debugger..? what are the values of the queryString can you at least show us that..? also you could convert the if conditional statement to use a switch(){ case } statement.. you need to provide more information.. — MethodMan
– MethodMan, Commented Apr 20, 2016 at 16:23

Bilgehan · Accepted Answer · 2016-04-28 12:23:02Z

1

You can use IMongoCollection to get your collection and then use AsQueryable

        var query = collection.AsQueryable();

        if (!string.IsNullOrEmpty(entity.Name))
            query = query.Where(p => p.Name.Contains(entity.Name));

        if (!string.IsNullOrEmpty(entity.Description))
            query = query.Where(p => p.Description.Contains(entity.Description));

        var YourList=query.ToList();

answered Apr 28, 2016 at 12:23

Bilgehan

1,2271 gold badge18 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to build a conditional query in MongoDB C#

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related