如何为不属于我的 MongoDB 集合创建一个类？

Question

I'm new to MongoDB and having some issues. Following this easy guide here ( http://docs.mongodb.org/ecosystem/tutorial/getting-started-with-csharp-driver ) but I'm instead connecting to a database that I did not personally create. So when the examples include something like:

var collection = database.GetCollection<Entity>("entities");

it doesn't work for the actual database i'm connecting to because I don't have the class. it's full of types that I can't just guess.. for example:

/* 0 */
{
  "_id" : ObjectId("54f0f990cea606d49fafd5h2"),
  "Time" : ISODate("2015-02-27T23:11:12.301Z"),
  "Timecode" : "15:11:12:18",
  "Round" : "1",
  "FighterID" : 5,
  "FighterName" : "John Doe",
  "TypeID" : 1,
  "Type" : "jab",
  "HandID" : 2,
  "Hand" : "left",
  "Force" : 0.0,
  "Velocity" : 8.0789527768068456,
  "Confidence" : 67.689217510307827,
  "ImpactType" : 1,
  "FightID" : "fea5dc60-b898-11e4-ac68-a5f571ea05d9"
}

i don't know how to make a class for that since the class members are rather complicated.

how do i go about doing this?

Answer 1

I am not aware of away to create the class out of mongodb just as we have with EF and linq-to-sql.

I suggest you do one of two things, and i believe the second solution will harder but closer to what you asking

1) Try use bsonextractelements attribute to catch all complicated fields

   public MyClass {
    // fields and properties
    [BsonExtraElements]
    public BsonDocument CatchAll { get; set; }
}

Or, 2)use reflection and store the name of properties as well as the data type of each property to txt file maybe. Then create your class manullay

Answer 2

Quite a late answer to the question, but I've been using this website to generate the C# classes for me. It works by parsing JSON data provided to it and generating the relevant class(es) that can be used to deserialise said Json.

It has a couple of hangups when it comes to dealing with json taken from MongoDB:

• It doesn't handle "ObjectId" and you'll get an initial parse error when you hit generate if you just use the Json pulled from Mongo. However, you can fix that easily by removing the "ObjectId" prefix (and accompanying parenthesis).

• It doesn't handle Json field names with spaces in it all that well, but it still generates a class for you that you can quickly "fix" any spaced fields

• If you have a collection of Json that has fluctuating amount of fields within it (IE, some documents includes "Diety" field, but some don't), then you need to paste in an array of json objects to ensure the generated class(es) cover all combinations possible

• As with the above, if you've got some fields that can be null, unless you include Json that illustrates this, the parser can't know that it should accept nulls, so make sure you either include enough examples to cover all combinations, or be prepared to make a few changes to the generated code yourself (like sticking a question mark after a few field types ;))

As I say - very late answer, but this question is coming up in Google quite a bit, so thought I'd add this in the hopes it helps someone else later on

Answer 3

Late answer, but maybe will help someone. Skipped few properties.

public class Entity
{
    [BsonId]
    public MongoDB.Bson.ObjectId _id { get; set; }

    [BsonElement("id")]
    public int Id { get; set; }

    [BsonElement("Time")]
    public DateTime Time{ get; set; }

    [BsonElement("Round")]
    public string Round{ get; set; }

    [BsonElement("Force")]
    public double? Force{ get; set; }

    [BsonElement("FightID")]
    public string FightID{ get; set; }
}

Answer 4

Even later to the party but (inspired by Sk93's answer) I've found this website ( http://bson2csharp.com/ ) that knows about MongoDB BSON.

UPDATE: website no longer exists