AutoMapper ProjectTo() blows up.

[VictorioBerra]

System.InvalidCastException: Unable to cast object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1[MyApp.API.ViewModels.InventoryServerViewModel]' to type 'System.Linq.IQueryable`1[MyApp.Entities.MyInventoryServer]'.
   at DataTables.Queryable.DataTablesQueryProvider`1.CreateQuery(Expression expression)
   at AutoMapper.QueryableExtensions.ProjectionExpression.Select(IQueryable source, LambdaExpression lambda) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\ProjectionExpression.cs:line 89
   at System.Linq.Enumerable.Aggregate[TSource,TAccumulate](IEnumerable`1 source, TAccumulate seed, Func`3 func)
   at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](Object parameters, Expression`1[] membersToExpand) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\ProjectionExpression.cs:line 62
   at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source, IConfigurationProvider configuration, Object parameters, Expression`1[] membersToExpand) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\Extensions.cs:line 60
   at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source, IConfigurationProvider configuration, Expression`1[] membersToExpand) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\Extensions.cs:line 76

http://docs.automapper.org/en/stable/Queryable-Extensions.html

https://github.com/AlexanderKrutov/DataTables.Queryable/blob/master/DataTables.Queryable/DataTablesQueryProvider.cs#L17-L25

My code:

            return queryable
               .Filter(request)
            .ProjectTo<TReturn>(mapperConfig)

I think ProjectTo is invoking CreateQuery because under the hood it runs .Select(). I am not sure, I am a little out of my experience zone. Maybe we need to be doing AsQueryable() instead of casing in the QueryProvider?

[AlexanderKrutov]

Hmm... I'm using DataTables.Queryable with AutoMapper too, but never faced with the same issue. May be it's because of Microsoft.EntityFrameworkCore.Query. Need time to verify.

[VictorioBerra]

Give me a minute and I'll get you a sample.

On Thu, Nov 1, 2018, 1:29 PM Alexander Krutov <notifications@github.com wrote:

Hmm... I'm using DataTables.Queryable with AutoMapper too, but never faced with the same issue. May be it's because of Microsoft.EntityFrameworkCore.Query. Need time to verify.

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[VictorioBerra]

@AlexanderKrutov here you go:

https://github.com/VictorioBerra/DataTables.Queryable.ProjectTo.Issue.29

The code that breaks is here: https://github.com/VictorioBerra/DataTables.Queryable.ProjectTo.Issue.29/blob/master/Program.cs#L90

To get started run these, it will automatically drop the SQLIte DB and migrate and seed on every run.

git clone https://github.com/VictorioBerra/DataTables.Queryable.ProjectTo.Issue.29.git
cd DataTables-ProjectTo-issue-29/
dotnet run

Unhandled Exception: System.InvalidCastException: Unable to cast object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1[EFCore.Models.CatViewModel]' to type 'System.Linq.IQueryable`1[EFCore.Models.Cat]'.
   at DataTables.Queryable.DataTablesQueryProvider`1.CreateQuery(Expression expression)
   at System.Linq.Enumerable.Aggregate[TSource,TAccumulate](IEnumerable`1 source, TAccumulate seed, Func`3 func)
   at AutoMapper.QueryableExtensions.ProjectionExpression.To[TResult](Object parameters, Expression`1[] membersToExpand) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\ProjectionExpression.cs:line 62
   at AutoMapper.QueryableExtensions.Extensions.ProjectTo[TDestination](IQueryable source, IConfigurationProvider configuration, Expression`1[] membersToExpand) in C:\projects\automapper\src\AutoMapper\QueryableExtensions\Extensions.cs:line 76
   at EFCore.Program.Main(String[] args) in C:\Users\me\Desktop\DataTables.Queryable.ProjectTo.Issue.29\Program.cs:line 90
   at EFCore.Program.<Main>(String[] args)

[VictorioBerra]

Grab this branch if you want a solution file and a local clone of DataTables.Queryable so you can debug it on the fly.

https://github.com/VictorioBerra/DataTables.Queryable.ProjectTo.Issue.29/tree/dtqueryable-project-referenced