Filter by enum column with parameters throws exception

[MaklaCof]

I am using version:

<PackageReference Include="System.Linq.Dynamic.Core" Version="1.0.11" />

I am trying to filter by enum and pass value as parameter, but I get exception

Expression of type 'System.Nullable`1[MyModule]' expected

This works:

this.Query<DbMenu>().Where("Module=4")

and this doesn't:

this.Query<DbMenu>().Where("Module=@0", 4)

Entity source:

public enum MyModule { Core, ... }

public class DbMenu
{
    public MyModule? Module {get;set;}
    ...
}

Callstack:

   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseConstantExpressionToEnum(Int32 pos, Type leftType, ConstantExpression constantExpr) in /Parser/ExpressionParser.cs:line 569
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseComparisonOperator() in /Parser/ExpressionParser.cs:line 460
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseLogicalAndOrOperator() in /Parser/ExpressionParser.cs:line 360
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseIn() in /Parser/ExpressionParser.cs:line 280
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseAndOperator() in /Parser/ExpressionParser.cs:line 263
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseOrOperator() in /Parser/ExpressionParser.cs:line 248
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseLambdaOperator() in /Parser/ExpressionParser.cs:line 231
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseNullCoalescingOperator() in /Parser/ExpressionParser.cs:line 218
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.ParseConditionalOperator() in /Parser/ExpressionParser.cs:line 201
   at System.Linq.Dynamic.Core.Parser.ExpressionParser.Parse(Type resultType, Boolean createParameterCtor) in /Parser/ExpressionParser.cs:line 140
   at System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda(ParsingConfig parsingConfig, Boolean createParameterCtor, ParameterExpression[] parameters, Type resultType, String expression, Object[] values) in /DynamicExpressionParser.cs:line 67
   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where(IQueryable source, ParsingConfig config, String predicate, Object[] args) in /DynamicQueryableExtensions.cs:line 2011
   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where[TSource](IQueryable`1 source, ParsingConfig config, String predicate, Object[] args) in /DynamicQueryableExtensions.cs:line 1983
   at System.Linq.Dynamic.Core.DynamicQueryableExtensions.Where[TSource](IQueryable`1 source, String predicate, Object[] args) in /DynamicQueryableExtensions.cs:line 1989

[StefH]

What framework do you use?

[MaklaCof]

Hi @StefH

.NET Core 2.2
Entity Framework 2.2.3
SQL Server

[StefH]

And does this work when you use a normal linq? Can you provide a full example project?

[MaklaCof]

Hi @StefH
Enum must be nullable. Here is demo.

[StefH]

OK. I see.

I will work probably if you use:

this.Query<DbMenu>().Where("Module=@0", (in?) 4)

However, for usability it would be better if this is built-in the code.

[MaklaCof]

It would be a lot better. Because I don't know if enum is nullable. I am using same code for all tables, so I don't know at compile time if table has any enum and if this enum is nullable. I could do it with reflection, but out of the box would be awesome.

[StefH]

Problem is found and fixed.

Can you try a preview version:
System.Linq.Dynamic.Core.1.0.12-ci-11129.nupkg

For using MyGet preview versions, see : https://github.com/StefH/System.Linq.Dynamic.Core/wiki/MyGet-preview-versions

[MaklaCof]

It works. Thank you.

[StefH]

Official NuGet (1.0.12) is uploaded and will be visible in some time...

[Genotypek]

Hey @StefH.
I found another problem:

DynamicExpressionParser.ParseLambda<TestEnum, bool>(ParsingConfig.DefaultEFCore21, true, "x => x==@0", TestEnum.Enum2);

It doesn't work. It can convert it into Expression, when enum is inside any class as property. But it doesn't work for Enum type itself.