Query: Simplifying Ternary expression in body of a Linq query breaks the query.

[paintballduke22]

Steps to reproduce

1: Create a users table that has a UserId int, HomePhone string, and MobilePhone string.
2: Insert a single record (UserId = 1, HomePhone = '1234567890', MobilePhone = '')

The issue

The following query works as intended:

 var results =
                from users in _db.Users                
                where users.UserId == 1
                select new
                {
                    UserID = users.UserId,
                    UserPhone = new
                    {
                        Number = users.HomePhone,
                        IsPrimary = string.IsNullOrEmpty(users.MobilePhone) ? false : true
                    },
                };

But simplifying the ternary operator on IsPrimary breaks the query and returns no results:

 var results =
                from users in _db.Users                
                where users.UserId == 1
                select new
                {
                    UserID = users.UserId,
                    UserPhone = new
                    {
                        Number = users.HomePhone,
                        IsPrimary = !string.IsNullOrEmpty(users.MobilePhone)
                    },
                };

Below are the exception that was thrown and the Stack Trace.

Exception message: [Error] An exception occurred in the database while iterating the results of a query.

Stack Trace:
System.Data.SqlClient.SqlException: An expression of non-boolean type specified in a context where a condition is expected, near 'THEN'.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlDataReader.TryConsumeMetaData()
   at System.Data.SqlClient.SqlDataReader.get_MetaData()
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
   at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior)
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, String executeMethod, IReadOnlyDictionary`2 parameterValues, Boolean openConnection, Boolean closeConnection)
   at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteReader(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues, Boolean manageConnection)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.QueryMethodProvider.<_ShapedQuery>d__3`1.MoveNext()
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
ClientConnectionId:392b7cbe-a1b6-4885-96e8-722ed2d776a2
Error Number:4145,State:1,Class:15

Further technical details

EF Core version: 1.0.1
Operating system: Windows 10
Visual Studio version: VS 2015

[paintballduke22]

The resulting sql that is generated is here as well.

Working query:
SELECT [users].[UserID], [users].[HomePhone], CASE WHEN [users].[MobilePhone] IS NULL OR ([users].[MobilePhone] = '') THEN CAST(0 AS BIT) ELSE CAST(1 AS BIT) END FROM [Users] AS [users] WHERE [users].[UserID] = 1

Non-working query:
SELECT [users].[UserID], [users].[HomePhone], CASE WHEN CASE WHEN [users].[MobilePhone] IS NULL OR ([users].[MobilePhone] = '') THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT) END THEN CAST(0 AS BIT) ELSE CAST(1 AS BIT) END FROM [Users] AS [users] WHERE [users].[UserID] = 1

[maumar]

This is now fixed. Currently we generate:

SELECT [users].[UserId], [users].[HomePhone], CASE
    WHEN [users].[MobilePhone] IS NOT NULL AND (([users].[MobilePhone] <> N'') OR [users].[MobilePhone] IS NULL)
    THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT)
END
FROM [Users] AS [users]
WHERE [users].[UserId] = 1