[Bug] ParseException: Operator '==' incompatible with operand types 'ObjectId' and 'ObjectId'

[aveyrier]

When using this library with the MongoDB.Driver package, an error occurs with the DynamicExpressionParser.ParseLambda method while trying to compare an object containing an ObjectId property with another ObjectId object.

This kind of comparison works fine inside a classic lambda expression (e.g. entity => entity.Id == ObjectId.Parse(id)) but it throws with the dynamic equivalent (e.g. "it.Id == @0"). Other operators doesn't work neither (>, <, >=, <=, !=) even though they are defined in the struct, but the Equals method works fine.

Code

private async Task<Todo> GetTodo(string id)
{
    ParameterExpression[] parameters = new[]
    {
        Expression.Parameter(typeof(Todo), "it"),
    };

    LambdaExpression find = DynamicExpressionParser.ParseLambda(parameters, typeof(bool), "it.Id == @0", ObjectId.Parse(id));

    return await _db.GetCollection<Todo>("Todos")
        .Find((Expression<Func<Todo, bool>>)find)
        .Limit(1)
        .SingleOrDefaultAsync();
}

Error

ParseException: Operator '==' incompatible with operand types 'ObjectId' and 'ObjectId'

Stacktrace

System.Linq.Dynamic.Core.ExpressionParser.CheckAndPromoteOperands(Type signatures, string opName, ref Expression left, ref Expression right, int errorPos)
System.Linq.Dynamic.Core.ExpressionParser.ParseComparisonOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseLogicalAndOrOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseIn()
System.Linq.Dynamic.Core.ExpressionParser.ParseAndOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseOrOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseLambdaOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseNullCoalescingOperator()
System.Linq.Dynamic.Core.ExpressionParser.ParseConditionalOperator()
System.Linq.Dynamic.Core.ExpressionParser.Parse(Type resultType, bool createParameterCtor)
System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(bool createParameterCtor, ParameterExpression[] parameters, Type resultType, string expression, Object[] values)
System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(ParameterExpression[] parameters, Type resultType, string expression, Object[] values)
TodoList.Controllers.TodosController+<GetEntity>d__4.MoveNext() in TodosController.cs
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
TodoList.Controllers.TodosController+<Get>d__3.MoveNext() in TodosController.cs
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeActionMethodAsync>d__27.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeNextActionFilterAsync>d__25.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeNextResourceFilter>d__22.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeAsync>d__20.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Builder.RouterMiddleware+<Invoke>d__4.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware+<Invoke>d__7.MoveNext()

[StefH]

Maybe when that ObjectId property implements the interface IComparable it can work ?
See https://msdn.microsoft.com/en-us/library/system.icomparable(v=vs.110).aspx

Else can you provide the full class from ObjectId ?

[aveyrier]

ObjectId implements the interface IComparable<ObjectId>. You can see below the full class (or you can see it here if you want the full implementation : https://github.com/mongodb/mongo-csharp-driver/blob/master/src/MongoDB.Bson/ObjectModel/ObjectId.cs).

public struct ObjectId : IComparable<ObjectId>, IEquatable<ObjectId>, IConvertible
{
    public ObjectId(byte[] bytes);
    public ObjectId(string value);
    public ObjectId(DateTime timestamp, int machine, short pid, int increment);
    public ObjectId(int timestamp, int machine, short pid, int increment);

    public static ObjectId Empty { get; }
    public short Pid { get; }
    public int Machine { get; }
    public int Timestamp { get; }
    public int Increment { get; }
    public DateTime CreationTime { get; }

    public static ObjectId GenerateNewId();
    public static ObjectId GenerateNewId(DateTime timestamp);
    public static ObjectId GenerateNewId(int timestamp);
    public static byte[] Pack(int timestamp, int machine, short pid, int increment);
    public static ObjectId Parse(string s);
    public static bool TryParse(string s, out ObjectId objectId);
    public static void Unpack(byte[] bytes, out int timestamp, out int machine, out short pid, out int increment);
    public int CompareTo(ObjectId other);
    public bool Equals(ObjectId rhs);
    public override bool Equals(object obj);
    public override int GetHashCode();
    public byte[] ToByteArray();
    public void ToByteArray(byte[] destination, int offset);
    public override string ToString();

    public static bool operator ==(ObjectId lhs, ObjectId rhs);
    public static bool operator !=(ObjectId lhs, ObjectId rhs);
    public static bool operator <(ObjectId lhs, ObjectId rhs);
    public static bool operator >(ObjectId lhs, ObjectId rhs);
    public static bool operator <=(ObjectId lhs, ObjectId rhs);
    public static bool operator >=(ObjectId lhs, ObjectId rhs);
}

[StefH]

I will take a look.

[loob91]

Are you sure this is closed ?

When I use this code :
var _expression = DynamicExpressionParser.ParseLambda<T, bool>(ParsingConfig.Default, false, _filterString, eavcustomattributes.id, _value.ToString());

Result is :
Param_1.value == 12/01/2017 00:00:00

And then I have the error :
Operator '==' incompatible with operand types 'DateTime?' and 'Int32'

I can understand it because there is no escape character for the date. Or maybe there is something I'm missing.