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ViewsHow to prevent _t and _v when inserting into MongoDB?
I'm utilizing Dictionary. After .insert() there are "_t" and "_v". Two posts here talked about serialization converting to JSON first then BSON. I'm using MongoDB's driver v2.4.3,
mCollection.InsertOne(x);
IMongoCollection<myDoc> mCollection = Db.GetCollection<myDoc>("whatever");
If I do JSON-to-BSON, it complains about can't convert BsonDocument to myDoc. Switching to IMongoCollection<BsonDocument> mCollection = Db.GetCollection<BsonDocument>("whatever"); still get _t and _v.
How to avoid _t and _v?
Here is my code of data type and utilization:
public class myObjForDictionary
{
//...
}
public class myDoc
{
// ... some other elements, then Dictionary
public Dictionary<string, object> myDictionary { get; set; }
}
// to instantiate the
class myClass
{
// define MongoDB connection, etc.
// instantiate myDoc and populate data
var x = new myDoc
{
//...
myDictionary = new Dictionary<string, object>
{
{ "type", "something" },
{ "Vendor", new object[0] },
{ "obj1", //data for myObjForDictionary
}
};
}
}
3 answers
Answer question0
I think you're looking for the DictionarySerializationOption... which gives you a couple of different options out of the box to determine how your dictionary gets serialized.
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You'll need to save some information (_t) of what object the deserializer needs to create when deserializing the object, if not it won't know what to create from the BSON.
Alternatively, you could change the Dictionary<string, object> to Dictionary<string, BsonDocument> and deal with the BsonDocuments directly within your code. This will be very similar to how you use JObject within Newtonsoft.Json.
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It also happens when the passed model to mongo is not exactly the type that is defined on the model.
In this case, mongo will add _t as it identifies that you expect to read the inheritor's class type, and not the type that is defined on the model.
For example:
public class ParentClass { }
public class ChildClass : ParentClass { }
public class ModelToInsert
{
public ParentClass property { get; set; }
}
...
// ChildClass is passed instead of ParentClass
collection.InsertOne(new ModelToInsert { property = new ChildClass() });