AzureDocumentDB: register Mongo conventions once per record type

MEVD/src/AzureDocumentDB/AzureDocumentDB.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <Version>1.0.1</Version>
+    <Version>1.0.2</Version>
     <AssemblyName>CommunityToolkit.VectorData.AzureDocumentDB</AssemblyName>
     <RootNamespace>$(AssemblyName)</RootNamespace>
     <TargetFrameworks>net10.0;net8.0;netstandard2.1;net472</TargetFrameworks>

MEVD/src/AzureDocumentDB/MongoShared/MongoMapper.cs

@@ -27,18 +27,10 @@ internal sealed class MongoMapper<TRecord> : IMongoMapper<TRecord>
     /// <summary>A key property name of the data model.</summary>
     private readonly string _keyPropertyModelName;
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="MongoMapper{TRecord}"/> class.
-    /// </summary>
-    /// <param name="model">The model.</param>
-    public MongoMapper(CollectionModel model)
+    static MongoMapper()
     {
-        this._model = model;
-
-        var keyProperty = model.KeyProperty;
-        this._keyPropertyModelName = keyProperty.ModelName;
-        this._keyClrProperty = keyProperty.PropertyInfo;
-
+        // ConventionRegistry is process-wide and every Register call adds a new entry,
+        // so the conventions are registered once per record type instead of once per instance.
         var conventionPack = new ConventionPack
         {
             new IgnoreExtraElementsConvention(ignoreExtraElements: true),
@@ -51,6 +43,19 @@ public MongoMapper(CollectionModel model)
             type => type == typeof(TRecord));
     }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MongoMapper{TRecord}"/> class.
+    /// </summary>
+    /// <param name="model">The model.</param>
+    public MongoMapper(CollectionModel model)
+    {
+        this._model = model;
+
+        var keyProperty = model.KeyProperty;
+        this._keyPropertyModelName = keyProperty.ModelName;
+        this._keyClrProperty = keyProperty.PropertyInfo;
+    }
+
     public BsonDocument MapFromDataToStorageModel(TRecord dataModel, int recordIndex, IReadOnlyList<Embedding>?[]? generatedEmbeddings)
     {
         var document = dataModel.ToBsonDocument();

MEVD/test/AzureDocumentDB.UnitTests/DocumentDBCollectionTests.cs

@@ -12,6 +12,7 @@
 using MongoDB.Bson;
 using MongoDB.Bson.Serialization;
 using MongoDB.Bson.Serialization.Attributes;
+using MongoDB.Bson.Serialization.Conventions;
 using MongoDB.Driver;
 using Moq;
 using Xunit;
@@ -72,6 +73,28 @@ public void ConstructorWithImperativeModelInitializesCollection()
         Assert.NotNull(collection);
     }
 
+    [Fact]
+    public void ConstructorRegistersConventionsOncePerRecordType()
+    {
+        // Arrange
+        using var firstCollection = new DocumentDBCollection<string, ConventionTestModel>(
+            this._mockMongoDatabase.Object,
+            "collection");
+
+        var conventionCount = ConventionRegistry.Lookup(typeof(ConventionTestModel)).Conventions.Count();
+
+        // Act
+        for (var i = 0; i < 3; i++)
+        {
+            using var collection = new DocumentDBCollection<string, ConventionTestModel>(
+                this._mockMongoDatabase.Object,
+                "collection");
+        }
+
+        // Assert
+        Assert.Equal(conventionCount, ConventionRegistry.Lookup(typeof(ConventionTestModel)).Conventions.Count());
+    }
+
     [Theory]
     [MemberData(nameof(CollectionExistsData))]
     public async Task CollectionExistsReturnsValidResultAsync(List<string> collections, string collectionName, bool expectedResult)
@@ -708,6 +731,15 @@ private sealed class VectorSearchModel
         [VectorStoreVector(dimensions: 4, DistanceFunction = DistanceFunction.CosineDistance, IndexKind = IndexKind.IvfFlat)]
         public ReadOnlyMemory<float> TestEmbedding2 { get; set; }
     }
+
+    private sealed class ConventionTestModel
+    {
+        [VectorStoreKey]
+        public string? Id { get; set; }
+
+        [VectorStoreData]
+        public string? HotelName { get; set; }
+    }
 #pragma warning restore CA1812
 
     #endregion