Web API controller for CRUD operations using mongoDB

Question

I'm trying to create an API controller for CRUD operations using mongoDB. Now keep in mind that I do not know the structure of these collections and the whole idea of using mongoDB is that we could really take advantage of the document storage option along with the ability to query without having to worry about designing models. Here is what I had before:

// GET api/mongo
public IEnumerable<BsonDocument> Get(String database, String collection)
{
    db = server.GetDatabase(database);
    return db.GetCollection(collection).FindAll().AsEnumerable();
}

But with the above I was getting this error:

{
    "Message": "An error has occurred.",
    "ExceptionMessage": "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.",
    "ExceptionType": "System.InvalidOperationException",
    "StackTrace": null,
    "InnerException": {
        "Message": "An error has occurred.",
        "ExceptionMessage": "Error getting value from '__emptyInstance' on 'MongoDB.Bson.ObjectId'.",
        "ExceptionType": "Newtonsoft.Json.JsonSerializationException",
        "StackTrace": "   at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value)\r\n   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value)\r\n   at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value)\r\n   at System.Net.Http.Formatting.JsonMediaTypeFormatter.<>c__DisplayClassd.<WriteToStreamAsync>b__c()\r\n   at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)",
        "InnerException": {
            "Message": "An error has occurred.",
            "ExceptionMessage": "Common Language Runtime detected an invalid program.",
            "ExceptionType": "System.InvalidProgramException",
            "StackTrace": "   at Get__emptyInstance(Object )\r\n   at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)"
        }
    }
}

MongoCusror has a method ToJson() using which I was able to get this:

[
    {
        "_id": ObjectId("520d4776a9a3f31f54ebdba6"),
        "name": "john"
    },
    {
        "_id": ObjectId("520d4b77a9a3f31f54ebdba7"),
        "name": "chi",
        "nickname": "cdawg"
    },
    {
        "_id": ObjectId("520d4c13a9a3f31f54ebdba8"),
        "name": "ak",
        "nickname": "afro",
        "address": {
            "state": "ny"
        }
    }
]

So from what I can see the Web API pipeline is having trouble using the available formatters to serialize the type ObjectId as it is not a simple type. This is the case even with the XML formatter.

I have re-written my method as follows:

// GET api/mongo
public JArray Get(String database, String collection)
{
    db = server.GetDatabase(database);
    return JArray.Parse(db.GetCollection(collection).FindAll().ToJson(new JsonWriterSettings { OutputMode = JsonOutputMode.Strict }));
}

This has worked for me and returns the following:

[
    {
        "_id": {
            "$oid": "520d4776a9a3f31f54ebdba6"
        },
        "name": "john"
    },
    {
        "_id": {
            "$oid": "520d4b77a9a3f31f54ebdba7"
        },
        "name": "chi",
        "nickname": "cdawg"
    },
    {
        "_id": {
            "$oid": "520d4c13a9a3f31f54ebdba8"
        },
        "name": "akash",
        "nickname": "ak",
        "address": {
            "state": "ny"
        }
    }
]

But I do not like this method for a number of reasons:

1. Setting accept header to'text/xml' does not work so it kind of kills Web API's awesomeness
2. It seems like such a waste to serialize the collection to JSON and then in-turn parse it again just to return it
3. I really really don't like it and there must be another better way to accomplish this

I've read about using the [BsonId] or [JsonIgnore] attributes etc, but, I do not have a strongly typed model to apply these against. And I would really like a way that can help me leverage Web API's content negotiation.

Your suggestions are much appreciated.