System.ArgumentNullException: Value cannot be null. Parameter name: source

[hossomi-baxenergy]

Hello everyone.

The project I'm working on was using version 1.0.0-beta and I'm trying to upgrade to 1.1.0. Looks like a small change in PropertyModelReferece is causing the exception at the bottom when processing a typecasting filter.

• In short, the model is an entity Child that extends Parent that has an Id property.
• The problem happens on requests with filters like /Parent$filter=Child/Id eq 1 (filter for Parent that are Child with Id = 1 right?)
  • Removing the Child part works fine: Parent$filter=Id eq 1.
  • There's are better ways to do this query, but I don't control the clients and this is just an example.
• Expanding Child properties that are expandable works fine.
• The source is a database using Entity Framework, and I can see the database query works and returns all Parent entities.
• .NET Framework 4.8.

Am I using Restier incorrectly or is this an oversight? I don't know exactly what other details I can provide, but let me know. In any case, can it be fixed in my code somehow?

Thanks!

---

Here's what I could find by debugging the code, but I don't know much about Restier internals so feel free to ignore:

• The exception happens in QueryExpressionContext.ComputeMemberModelReference when processing a TypeAs expression. The method GetModelReferenceForNode returns null, and creating a PropertyModelReference then throws because source is null.
• The difference is that in 1.0.0-rc1 it uses the PropertyModelReference constructor that doesn't null-check source, while in newer versions it always checks.
• Going a little further, I noticed that the filter becomes a Linq expression like GetQueryableSource("Parent", null).Where($it => ($it As Child).Id == 1). Linq's ExpressionVisitor.VisitLambda processes the lambda body before the lambda parameters. GetModelReferenceForNode tries to get the expression for $it from the model references cache, but doesn't find it, returning null. Using the debugger, I forced it to visit the parameters first, which adds $it to the cache, and it worked somehow.

System.ArgumentNullException: Value cannot be null.
Parameter name: source
   at void Ensure.NotNull<T>(T value, string paramName)
   at new Microsoft.Restier.Core.Query.PropertyModelReference(QueryModelReference source, string propertyName) x 2
   at QueryModelReference Microsoft.Restier.Core.Query.QueryExpressionContext.ComputeMemberModelReference(MemberExpression member)
   at QueryModelReference Microsoft.Restier.Core.Query.QueryExpressionContext.ComputeModelReference()
   at void Microsoft.Restier.Core.Query.QueryExpressionContext.UpdateModelReference()
   at void Microsoft.Restier.Core.Query.QueryExpressionContext.PushVisitedNode(Expression visitedNode)
   at Expression Microsoft.Restier.Core.Query.DefaultQueryHandler+QueryExpressionVisitor.Visit(Expression node)
   at Expression System.Linq.Expressions.ExpressionVisitor.VisitBinary(BinaryExpression node)
   at Expression System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at Expression System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Expression Microsoft.Restier.Core.Query.DefaultQueryHandler+QueryExpressionVisitor.Visit(Expression node)
   at Expression System.Linq.Expressions.ExpressionVisitor.VisitLambda<T>(Expression<T> node)
   at Expression System.Linq.Expressions.Expression<TDelegate>.Accept(ExpressionVisitor visitor)
   at Expression System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Expression Microsoft.Restier.Core.Query.DefaultQueryHandler+QueryExpressionVisitor.Visit(Expression node)
   at Expression System.Linq.Expressions.ExpressionVisitor.VisitUnary(UnaryExpression node)
   at Expression System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at Expression System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Expression Microsoft.Restier.Core.Query.DefaultQueryHandler+QueryExpressionVisitor.Visit(Expression node)
   at Expression[] System.Linq.Expressions.ExpressionVisitor.VisitArguments(IArgumentProvider nodes)
   at Expression System.Linq.Expressions.ExpressionVisitor.VisitMethodCall(MethodCallExpression node)
   at Expression System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
   at Expression System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Expression Microsoft.Restier.Core.Query.DefaultQueryHandler+QueryExpressionVisitor.Visit(Expression node)
   at async Task<QueryResult> Microsoft.Restier.Core.Query.DefaultQueryHandler.QueryAsync(QueryContext context, CancellationToken cancellationToken)
   at async Task<QueryResult> Microsoft.Restier.Core.ApiBaseExtensions.QueryAsync(ApiBase api, QueryRequest request, CancellationToken cancellationToken)
   at async Task<IQueryable> Microsoft.Restier.AspNet.RestierController.ExecuteQuery(IQueryable queryable, CancellationToken cancellationToken)
   at async Task<HttpResponseMessage> Microsoft.Restier.AspNet.RestierController.Get(CancellationToken cancellationToken)
   at async Task<object> System.Threading.Tasks.TaskHelpersExtensions.CastToObject<T>(Task<T> task)
   at async Task<HttpResponseMessage> System.Web.Http.Controllers.ApiControllerActionInvoker.InvokeActionAsyncCore(HttpActionContext actionContext, CancellationToken cancellationToken)
   at async Task<HttpResponseMessage> System.Web.Http.Controllers.ActionFilterResult.ExecuteAsync(CancellationToken cancellationToken)
   at async Task<HttpResponseMessage> System.Web.Http.Filters.AuthorizationFilterAttribute.ExecuteAuthorizationFilterAsyncCore(HttpActionContext actionContext, CancellationToken cancellationToken, Func<Task<HttpResponseMessage>> continuation)
   at async Task<HttpResponseMessage> System.Web.Http.Controllers.ExceptionFilterResult.ExecuteAsync(CancellationToken cancellationToken)