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  1. C# Driver
  2. CSHARP-4993

Divide Decimal in Projection throws TruncationException

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    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Unknown Unknown
    • 2.25.0
    • Affects Version/s: 2.24.0
    • Component/s: None
    • Labels:
      None
    • Fully Compatible
    • Dotnet Drivers
    • Not Needed
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      1. What would you like to communicate to the user about this feature?
      2. Would you like the user to see examples of the syntax and/or executable code and its output?
      3. Which versions of the driver/connector does this apply to?

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      1. What would you like to communicate to the user about this feature? 2. Would you like the user to see examples of the syntax and/or executable code and its output? 3. Which versions of the driver/connector does this apply to?

      Summary

      When attempting to project a calculated property of type decimal, the divide operator throws System.FormatException due to a TruncationException error.

      System.FormatException
  HResult=0x80131537
  Message=An error occurred while deserializing the GBP property of class <>f__AnonymousType0`2[[System.Decimal, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Decimal, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]: Truncation resulted in data loss.
  Source=MongoDB.Bson
  StackTrace:
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeClass(BsonDeserializationContext context)
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize[TValue](IBsonSerializer`1 serializer, BsonDeserializationContext context)
   at MongoDB.Bson.Serialization.Serializers.EnumerableSerializerBase`2.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize[TValue](IBsonSerializer`1 serializer, BsonDeserializationContext context)
   at MongoDB.Driver.Core.Operations.AggregateOperation`1.CursorDeserializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize[TValue](IBsonSerializer`1 serializer, BsonDeserializationContext context)
   at MongoDB.Driver.Core.Operations.AggregateOperation`1.AggregateResultDeserializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize[TValue](IBsonSerializer`1 serializer, BsonDeserializationContext context)
   at MongoDB.Driver.Core.WireProtocol.CommandUsingCommandMessageWireProtocol`1.ProcessResponse(ConnectionId connectionId, CommandMessage responseMessage)
   at MongoDB.Driver.Core.WireProtocol.CommandUsingCommandMessageWireProtocol`1.Execute(IConnection connection, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.WireProtocol.CommandWireProtocol`1.Execute(IConnection connection, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Servers.Server.ServerChannel.ExecuteProtocol[TResult](IWireProtocol`1 protocol, ICoreSession session, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Servers.Server.ServerChannel.Command[TResult](ICoreSession session, ReadPreference readPreference, DatabaseNamespace databaseNamespace, BsonDocument command, IEnumerable`1 commandPayloads, IElementNameValidator commandValidator, BsonDocument additionalOptions, Action`1 postWriteAction, CommandResponseHandling responseHandling, IBsonSerializer`1 resultSerializer, MessageEncoderSettings messageEncoderSettings, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.CommandOperationBase`1.ExecuteProtocol(IChannelHandle channel, ICoreSessionHandle session, ReadPreference readPreference, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.ReadCommandOperation`1.ExecuteAttempt(RetryableReadContext context, Int32 attempt, Nullable`1 transactionNumber, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.RetryableReadOperationExecutor.Execute[TResult](IRetryableReadOperation`1 operation, RetryableReadContext context, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.ReadCommandOperation`1.Execute(RetryableReadContext context, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.AggregateOperation`1.Execute(RetryableReadContext context, CancellationToken cancellationToken)
   at MongoDB.Driver.Core.Operations.AggregateOperation`1.Execute(IReadBinding binding, CancellationToken cancellationToken)
   at MongoDB.Driver.OperationExecutor.ExecuteReadOperation[TResult](IReadBinding binding, IReadOperation`1 operation, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.ExecuteReadOperation[TResult](IClientSessionHandle session, IReadOperation`1 operation, ReadPreference readPreference, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.ExecuteReadOperation[TResult](IClientSessionHandle session, IReadOperation`1 operation, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.Aggregate[TResult](IClientSessionHandle session, PipelineDefinition`2 pipeline, AggregateOptions options, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.<>c__DisplayClass22_0`1.<Aggregate>b__0(IClientSessionHandle session)
   at MongoDB.Driver.MongoCollectionImpl`1.UsingImplicitSession[TResult](Func`2 func, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.Aggregate[TResult](PipelineDefinition`2 pipeline, AggregateOptions options, CancellationToken cancellationToken)
   at MongoDB.Driver.CollectionAggregateFluent`2.ToCursor(CancellationToken cancellationToken)
   at MongoDB.Driver.IAsyncCursorSourceExtensions.ToList[TDocument](IAsyncCursorSource`1 source, CancellationToken cancellationToken)
   at Methods.ProjectWithDivideDecimal(IMongoCollection`1 items) in C:\Stuff\Documents\Programming\C#\Projects\MongoDbDivide\Program.cs:line 54
   at Program.<Main>$(String[] args) in C:\Stuff\Documents\Programming\C#\Projects\MongoDbDivide\Program.cs:line 12  This exception was originally thrown at this call stack:
    [External Code]Inner Exception 1:
TruncationException: Truncation resulted in data loss.

      .NET 8.0

      C# Driver Version = 2.24.0

      MongoDB Server version = (Atlas) 6.0.14 , Region: AZURE California (westus)

      How to Reproduce

      1.   
        dotnet new console --framework net8.0
dotnet add package MongoDB.Driver
      1. Paste the following code into the Program.cs file
      using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Bson;
using MongoDB.Driver;

const string connectionUri = "<REDACTED>";
var client = new MongoClient(connectionUri);
var db = client.GetDatabase("db");
var items = db.GetCollection<Item>("items");

await Methods.InsertOne(items);
Methods.ProjectWithDivideDecimal(items);

internal sealed class Item
{
    public static Item SampleItem => new()
    {
        Balance = 1000
    };
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; } = string.Empty;

    [BsonElement("balance")]
    [BsonRepresentation(BsonType.Decimal128)]
    public decimal Balance { get; set; }

    public override string ToString()
    {
        return $"Id = {Id}, Balance = {Balance}";
    }
}

internal static class Methods
{
    public static async Task InsertOne(IMongoCollection<Item> items)
    {
        await items.InsertOneAsync(Item.SampleItem);
    }

    public static void ProjectWithDivideDecimal(IMongoCollection<Item> items)
    {
        var projectStage = Builders<Item>.Projection.Expression(a => new
        {
            a.Balance,
            GBP = a.Balance / 1.30M
        });

        var aggr = items.Aggregate()
            .Project(projectStage);

        var results = aggr.ToList(); // TruncationException!
        results.ForEach(Console.WriteLine);
    }
}
      1. Run
      2. You should see an exception thrown on this line:
      var results = aggr.ToList();

      Additional Background

      I've attached a .zip file with the reproducible project.

            Assignee:
            robert@mongodb.com Robert Stam
            Reporter:
            leegrissom@gmail.com Lee Grissom
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              Created:
              Updated:
              Resolved: