Adding TKey support

MongoDbGenericRepository/IMongoDbContext.cs

@@ -1,5 +1,6 @@
 using MongoDB.Driver;
 using MongoDbGenericRepository.Models;
+using System;
 
 namespace MongoDbGenericRepository
 {
@@ -31,6 +32,16 @@ namespace MongoDbGenericRepository
         /// <param name="partitionKey">The value of the partition key.</param>
         IMongoCollection<TDocument> GetCollection<TDocument>(string partitionKey) where TDocument : IDocument;
 
+        /// <summary>
+        /// Returns a collection for a document type that has a partition key.
+        /// </summary>
+        /// <typeparam name="TDocument">The type representing a Document.</typeparam>
+        /// <typeparam name="TKey">The type of the primary key for a Document.</typeparam>
+        /// <param name="partitionKey">The value of the partition key.</param>
+        IMongoCollection<TDocument> GetCollection<TDocument, TKey>(string partitionKey)
+            where TDocument : IDocument<TKey>
+            where TKey : IEquatable<TKey>;
+
         /// <summary>
         /// Drops a collection, use very carefully.
         /// </summary>