Query: Rewrite Entity Equality

[smitpatel]

No description provided.

[Pentadome]

Is it possible to use ==null in a Where method? If not, is there an alternative to do this? I get "Null TypeMapping in Sql Tree" error when I do.

[alexk8]

This issue is considered to be closed in preview7, but in preview7 I still encounter an error, which is now a bit different
(original issue comment )
code

context.children.Where(x => x.parentRef.id==aParentEntity.id).ToList(); //fine
context.children.Where(x => x.parentRef==aParentEntity).ToList(); // error
// context.Entry(aParentEntity).State == Unchanged

InvalidOperationException: Operation is not valid due to the current state of the object

Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalSqlTranslatingExpressionVisitor.BindProperty(Expression source, string propertyName)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalSqlTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalSqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
Microsoft.EntityFrameworkCore.SqlServer.Query.Pipeline.SqlServerSqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalSqlTranslatingExpressionVisitor.Translate(Expression expression)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateExpression(Expression expression)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateLambdaExpression(ShapedQueryExpression shapedQueryExpression, LambdaExpression lambdaExpression)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateWhere(ShapedQueryExpression source, LambdaExpression predicate)
Microsoft.EntityFrameworkCore.Query.Pipeline.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
Microsoft.EntityFrameworkCore.Query.Pipeline.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
Microsoft.EntityFrameworkCore.Query.Pipeline.QueryCompilationContext.CreateQueryExecutor<TResult>(Expression query)
Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery<TResult>(Expression query, bool async)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore<TResult>(IDatabase database, Expression query, IModel model, bool async)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler+<>c__DisplayClass9_0<TResult>.<Execute>b__0()
Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore<TFunc>(object cacheKey, Func<Func<QueryContext, TFunc>> compiler)
Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery<TResult>(object cacheKey, Func<Func<QueryContext, TResult>> compiler)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute<TResult>(Expression query)
Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute<TResult>(Expression expression)
Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable<TResult>.GetEnumerator()
System.Collections.Generic.List<T>..ctor(IEnumerable<T> collection)
System.Linq.Enumerable.ToList<TSource>(IEnumerable<TSource> source)

Entity Framework Core 3.0.0-preview7.19362.6

[smitpatel]

@alexk8 - Since your query is using local variable in equality, the issue you are hitting is #15855. It is fixed in nightly builds and will be released in preview8.