MongoDB c# LINQ generated query

Question

How can I get the generated query from the LINQ query? I tried this but it didnt work:

var query = (
            from d in mcollection.AsQueryable<InstrumentationDocument>()
            where d.user == User && d.timestamp > DateTime.Today.AddDays(-days)
            orderby d.timestamp descending
            select new
            {
                d.timestamp,
                d.machine,
                d.processID,
                feature = d.info["feature"].AsString,
                extra = d.info.Contains("extra") ? d.info["extra"].ToJson() : ""
            }
);

var mongoQuery = ((MongoQueryable<InstrumentationDocument>)query).GetMongoQuery();

var json = mongoQuery.ToJson();

where InstrumentationDocument is

class InstrumentationDocument
{
    [BsonId]
    public ObjectId _id { get; set; }

    [BsonDateTimeOptions(Kind = DateTimeKind.Local)]
    public DateTime timestamp { get; set; }

    public string user { get; set; }
    public string machine { get; set; }
    public int processID { get; set; }
    public BsonDocument info { get; set; }
}

Did you set a breakpoint on the mongoQuery.ToJson() to read the value of this expression or are you writing it to a log/console? From your code example, it seems like you're not getting the query because there is no variable to read, and it's not being written anywhere. — CassOnMars
– CassOnMars, Commented Dec 28, 2012 at 16:08
Can you post what query is? We can't really help you unless we have all the details. — Craig Wilson
– Craig Wilson, Commented Dec 28, 2012 at 22:38

Craig Wilson · Accepted Answer · 2013-01-03 14:38:10Z

1

You need to remove .ToArray() from your code. Currently, query is NOT a MongoQueryable instance. It is an array of anonymous types. Hence, your cast to MongoQueryable should NOT be working.

answered Jan 3, 2013 at 14:38

Craig Wilson

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1 Comment

Nestor Over a year ago

Thank you. I actually had it without the ToArray in my code. The problem seems to actually be the projection into annonymous type new {} at the end. That type is not an InstrumentationDocument, therefore it cannot cast query into MongoQueryable<InstrumentationDocument>

Contango · Accepted Answer · 2014-07-25 00:05:42Z

0

Its much simpler in the latest version of MongoDB (v2.6), just call .ToJson() on the LINQ query, then print the query string to the console.

string queryTextSentToMongoDb = query.ToJson();

answered Jul 25, 2014 at 0:05

Contango

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1 Comment

Ralph Shillington Over a year ago

Really? Because I would think that would cause the query to execute, and the ToJson() to be the actual results of the query, not the definition of the query that was sent to MongoDb

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