在带有 C# 的点网核心中使用带有 mongo 驱动程序的过滤器时如何忽略大小写

Question

I have an aggregates pipeline query as below:

string [] sids   = { array of Student ids here };
string deptName = "math";
var pipeline = new BsonDocument[]
    {
        new BsonDocument("$match",
            new BsonDocument
            {
                {"studentid", new BsonDocument("$in",BsonArray.Create(sids))},
                {"dept",BsonRegularExpression.Create(new Regex( dept, RegexOptions.IgnoreCase))}
            }
        ),
            new BsonDocument("$sort",new BsonDocument("CardSwipeTimestamp", -1)),
                               
            new BsonDocument("$group",
                new BsonDocument{
                        { "_id",
                            new BsonDocument
                            {
                                { "studentid","$studentid" },
                                { "dept","$dept"}
                            }
                        },
                        { "Status",new BsonDocument("$first", "$Status")},
                        { "CardSwipeTimestamp",new BsonDocument("$first", "$CardSwipeTimestamp")}
                    }
                ),
       new BsonDocument("$project",
            new BsonDocument
            {
                { "_id", 0 },
                { "studentid", "$_id.studentid" },
                { "dept", "$_id.dept" },
                { "Status", "$Status" },
                { "CardSwipeTimestamp", "$CardSwipeTimestamp" }
            }
        ),
         new BsonDocument("$skip",0),
         new BsonDocument("$limit",3),
    };

collectionName.Aggregate<BsonDocument>(pipeline).ToList()

These only returns a value if the department passed in matches the case of what is stored in the collection.

How to ignore the case of the incoming parameter when doing a search using the above query?

Answer 1

You could convert the two sides of the match expression to lowercase with ToLower()

ToLower(left operand).equal(ToLower(right operand))  //so we can ignore case.