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1

Im working on a project that use .NET Razor and mongodb. I would like to do something like this:

@{
    var feeds = DP.Database.GetCollection("feeds").FindAll();
}
<ul>
    @foreach (dynamic feed in feeds)
    {
        <li>@feed.message - @feed.from.name</li>
    }
</ul>

However, the current mongodb C# driver FindAll() return collection of BsonDocument which does not support dynamic object. Anybody know a .NET 4 dynamic supported mongodb C# driver?

Thanks a lot

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3 Answers

up vote 7 down vote accepted

Currently, there is no support for dynamic in the MongoDB driver. This is because it is based on .NET 3.5. However, since a .NET 4.0 assembly can reference a .NET 3.5 assembly, it is possible for you to write a IBsonSerializationProvider and an IBsonSerializer in .NET 4.0 to support dynamics.

We, 10gen, are looking at doing this in the future. I have spiked some support at https://github.com/craiggwilson/mongo-csharp-driver/tree/dynamic if you want to take a look. There are most definitely bugs, but it shows that it is possible.

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Thanks Craig, i found a way to make it work. check here groups.google.com/forum/?fromgroups#!topic/mongodb-user/… – hoang Apr 20 '12 at 4:46
Yes, I saw that. I will echo here for SO users. That works fine, but requires a low level modification to the core. The way I presented above is a side-load and accomplishes the same thing without modifying the core. Obviously, there are some differences, but it gets most of the way there. It is just a spike after all, so... – Craig Wilson Apr 20 '12 at 16:34
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Take a look at MongoDB.Dynamic. It uses MongoDB official driver and take an approach of using interfaces with dynamics of C# 4.0. – Jone John Polvora Jun 4 '12 at 20:49
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up vote 7 down vote

I created a straight-forward extension to the MongoDB driver that re-serializes the bson document using JSON.Net and deserializes it as a dynamic. By inlcuding the following class, you can simply convert your mongo queries to dynamic like this

dynamic obj = collection.FindOneByIdAs<BsonDocument>(someObjectId).ToDynamic();

Extension class:

public static class MongoDynamic
{
    private static System.Text.RegularExpressions.Regex objectIdReplace = new System.Text.RegularExpressions.Regex(@"ObjectId\((.[a-f0-9]{24}.)\)", System.Text.RegularExpressions.RegexOptions.Compiled);
    /// <summary>
    /// deserializes this bson doc to a .net dynamic object
    /// </summary>
    /// <param name="bson">bson doc to convert to dynamic</param>
    public static dynamic ToDynamic(this BsonDocument bson)
    {
        var json = objectIdReplace.Replace(bson.ToJson(), (s) => s.Groups[1].Value);
        return Newtonsoft.Json.JsonConvert.DeserializeObject<dynamic>(json);
    }
}

Be sure to reference Newtonsoft.Json.dll (http://james.newtonking.com/projects/json-net.aspx)

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up vote 2 down vote

Just to build on Maximilian's answer. This will return a list of dynamics from any query.

    /// <summary>
    /// deserializes this BsonDocument cursor result to a list of .net dynamic objects
    /// </summary>
    /// <param name="cursor">cursor result to convert to dynamic</param>
    /// <returns></returns>
    public static List<dynamic> ToDynamicList(this MongoCursor<BsonDocument> cursor)
    {
        var dynamicList = new List<dynamic>();
        var list = cursor.ToList();
        for (int i = 0, l = list.Count; i < l; i++)
            dynamicList.Add(list[i].ToDynamic());

        return dynamicList;
    }
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This seems redundant. You could just do cursor.Select(doc => doc.ToDynamic()). Add .ToList() if needed. In general, writing methods for which the framework already provides a good solution should be avoided. – Tomas Mar 25 at 15:23
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