add getting started wiki page about entityframeworkcore

[crhairr]

It's already in the works! I've started a documentation branch for adding all of the relevant XML docs to the code as well for consumption with Intellisense.

[crhairr]

The first two wiki entries have been created:
https://github.com/crhairr/EntityFrameworkCore.MongoDb/wiki/Getting-Started

[ErikEJ]

Great - the use of attributes looks slightly strange in a EF Core context, in particular this:
[MongoDatabase("zooDb")] - could the UseMongoDb method be extended with a second parameters for the database name?

[crhairr]

Not currently, but you can configure the database in OnModelCreating (essentially what the attribute is doing):

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            new InternalModelBuilder(modelBuilder.Model.AsModel())
                .MongoDb(ConfigurationSource.Explicit)
                .FromDatabase("zooDb");
        }

This is quite clunky since Microsoft decided to split their builders into public and internal versions where the InternalModelBuilder takes a Model instead of an IMutableModel for some unobvious reason. This is why I prefer the attribute. I will probably end up adding a property to the options extension since that would be more concise than the above. But I think that anybody already familiar with the MongoDb C# driver would also prefer the straight-forward, declarative, aspect-oriented style of the attributes.

FWIF, the Bson* attributes are what the driver uses to create its BsonClassMap mappings, so I've implemented conventions to support those to make it easier for people already familiar with the driver to adopt this provider. I do intend at some point to add conventions to the adapter to support attributes used by EF Core (like Key and DatabaseGenerated) so that a BsonClassMap can be created from a "standard" EF Core model.

[vdavi]

This is fantastic! Can you tell me if there is built in support for accessing the .aggregate functionality for mongoDb?
I'v been spending months evaluating a completely different tech stack, (Meteor) and I've hit a dead end regarding aggregate usage while also using angular 2. (Long story)

[crhairr]

EDIT: this project wraps the MongoDB C# Driver, and DbSet<T> is essentially implemented as mongoDatabase.GetCollection<T>.AsQueryable<T>(). Anything that you can do with their Linq provider, you can do with a linq query using EFCore-MongoDB.

But, if you need more than that and must use the aggregation framework directly, read on...

END EDIT

It's possible, but there's currently no direct support for it through EFCore-MongoDB. I plan to expose this a bit more fluidly using extension methods on DbSet<T>. In the meantime, you should be able to use the MongoDB C# driver's aggregation framework by injecting an IMongoDbConnection into your class constructor and using it something like this:

public IEnumerable<T> AggregateTheThings<T>()
{
    var pipeline = new AggregateArgs()
    {
        /*do your thing here*/
    };
    return _mongoDbConnection
        .GetCollection<T>
        .Aggregate(pipeline);
}

You can find some examples of using the driver's Aggregate method here: http://mikaelkoskinen.net/post/mongodb-aggregation-framework-examples-in-c.

Note: you might encounter some issues if your collection contains polymorphic documents. Be sure to supply the base document type to GetCollection<T>. I already have a fix for this that will ensure that the correct collection for a polymorphic subtype is always returned, which will be committed in the next few days as part of an Identity provider for MongoDB.