使用C＃mongo驱动程序构建查询

Question

我不知道如何使用mongo驱动程序构建复杂查询。这是我的查询：

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(); 

随着EFIQueryable此代码工作正常，但我不能mongo driver建立正确的查询。 谁能告诉我我做错了什么？

Answer 1

知道什么finalExpression是有帮助的，以防出现问题。在我看来，有可能是与!(x.Promo == null && x.Promo == string.Empty)

MongoDB的驱动程序的翻译，你可以试试下面的代码，而不是你的，看它是否会有所作为

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();