Nesting BsonDocuments in MongoDB queries

Question

I have a MongoDB collection setup where each document's JSON looks like this:

{
 "_id" : "Stuff",
 "project_id" : "1234",
 "VehicleEntry" : [
 {
 // Irrelevant fields removed.
 "VehicleStatus" : "PASSED"
 },
 {
 // Irrelevant fields removed.
 "VehicleStatus" : "FAILED"
 }
 ]
}

I want to write a query that gives me the number of vehicles passed and failed for each project identifier. I have done so in this very long aggregation query:

var aggregate = collection.Aggregate()
 .Match(new BsonDocument
 {
 {
 "project_id", "1234"
 }
 })
 .Unwind(i => i["VehicleEntry"])
 .Group(new BsonDocument
 {
 {
 "_id", "$project_id"
 },
 {
 "passed", new BsonDocument
 {
 {
 "$sum", new BsonDocument
 {
 {
 "$cond", new BsonArray
 {
 new BsonDocument
 {
 {
 "$eq", new BsonArray 
 {
 "$VehicleEntry.VehicleStatus", 
 "PASSED"
 }
 }
 },
 1,
 0
 }
 }
 }
 }
 }
 },
 {
 "failed", new BsonDocument
 {
 {
 "$sum", new BsonDocument
 {
 {
 "$cond", new BsonArray
 {
 new BsonDocument
 {
 {
 "$eq", new BsonArray
 {
 "$VehicleEntry.VehicleStatus",
 "FAILED"
 }
 }
 },
 1,
 0
 }
 }
 }
 }
 }
 }
 });

While it works as expected, this seems very difficult to maintain and has even become unreadable. How can I improve the way this is written to be more maintainable?

If it's relevant to a better solution, I already have the Newtonsoft library in my project as I use it to convert Json to Bson.

EDIT I have been told I could serialize Bson to do this, but I am not familiar with the concept. What are some best practices for that and how can I convert this query to use serialized bson?

Answer 1

I found one way to simplify this which helps break up the number of rows required.

Following this StackOverflow question about converting a JSON string to Bson, I wrote part of my query as it would be in a console. I could only figure out how to do this for the match and group part:

var matchJSON = "{ project_id : '1234' }";
var groupJSON = "{ " + 
 "_id : { project_id : '$project_id', date : '$VehicleEntry.@Date' }, " + 
 "passed : { $sum : { $cond : [ { $eq : [ '$VehicleEntry.VehicleStatus', 'PASSED' ] }, 1, 0 ] } }, " + 
 "failed : { $sum : { $cond : [ { $eq : [ '$VehicleEntry.VehicleStatus', 'FAILED' ] }, 1, 0 ] } } }";

Then I converted it to BsonDocuments:

var matchBson = MongoDB.Bson.Serialization.BsonSerializer.Deserialize<BsonDocument>(matchJSON);
var groupBson = MongoDB.Bson.Serialization.BsonSerializer.Deserialize<BsonDocument>(groupJSON);

and then ran my aggregate query just like it was previously:

var aggregate = collection.Aggregate()
 .Match(matchBson)
 .Unwind(i => i["VehicleEntry"])
 .Group(groupBson);