Build query with C# mongo driver

Question

I wonder how to build complex query using mongo driver. This is my query:

var builder = Builders<MongoNavFilter>.Filter;
var query = builder.Where(x => x.Link == link && x.SubLink == subLink);
if (some statement)
{
    var finalExpression = ...
    query = query & Builders<MongoNavFilter>.Filter.Where(finalExpression); 
}
if (onsale)
    query = query & Builders<MongoNavFilter>.Filter.Where(x => !(x.Promo == null && x.Promo == string.Empty));

var filters = _db.GetCollection<MongoNavFilter>("NavFilters").
                    Find(query).ToList();

With EF IQueryable this code is working fine, but I can't build correct query with mongo driver. Could anyone told me what am I doing wrong?

Please update your post with sample MongoDB documents. Also mention what do you mean by "can't build correct query?" what error do you get? — Saleem
– Saleem, Commented Mar 20, 2016 at 14:42

M. Mennan Kara · Accepted Answer · 2016-03-20 19:06:51Z

5

Knowing what the finalExpression is would help, in case the problem is there. In my opinion, there might be a problem with mongodb driver's translation of !(x.Promo == null && x.Promo == string.Empty)

Could you try the following code instead of yours and see if it will make a difference

var builder = Builders<MongoNavFilter>.Filter;
var query = builder.Eq(x => x.Link, link) & builder.Eq(x=> x.SubLink, subLink);
if (some statement)
{
    var finalExpression = ... // write this using the same syntax 
    query = query & filter; 
}
if (onsale)
    query = query & builder.Ne(x=>x.Promo, null) & builder.Ne(x=> x. Promo, string.Empty);

var filters = _db.GetCollection<MongoNavFilter>("NavFilters").
                Find(query).ToList();

answered Mar 20, 2016 at 19:06

M. Mennan Kara

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1 Comment

Alex Gurskiy Over a year ago

Thanks a lot for your time!

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