Entity Framework 6 Code Prima su SQL Server: Mappare "bool" su "numerico (1,0)" invece di "bit"

Ecco un modo per armare l'EF6 nella gestione di colonne numeriche (1.0) come colonne BIT. Non è la cosa migliore di sempre e l'ho solo testato negli scenari mostrati in basso, ma funziona in modo affidabile per quanto riguarda i miei test. Se qualcuno rileva un caso in cui le cose non vanno come previsto, sentitevi liberi di lasciare un commento e io migliorerò questo approccio:

<!-- add this to your web.config / app.config -->
<entityFramework>
    [...]
    <interceptors>
        <interceptor type="[Namespace.Path.To].MsSqlServerHotFixerCommandInterceptor, [Dll hosting the class]">
        </interceptor>
    </interceptors>
</entityFramework>

E l'implementazione dell'intercettatore:

// to future maintainers     the reason we introduced this interceptor is that we couldnt find a way to persuade ef6 to map numeric(1,0) columns in sqlserver into bool columns
// to future maintainers     we want this sort of select statement
// to future maintainers     
// to future maintainers        SELECT 
// to future maintainers           ...
// to future maintainers           [Extent2].[FB_YN]  AS [FB_YN], 
// to future maintainers           ...
// to future maintainers        FROM  ...
// to future maintainers     
// to future maintainers     to be converted into this sort of select statement
// to future maintainers     
// to future maintainers        SELECT 
// to future maintainers           ...
// to future maintainers           CAST ([Extent2].[FB_YN]  AS BIT) AS [FB_YN],    -- the BIT cast ensures that the column will be mapped without trouble into bool properties
// to future maintainers           ...
// to future maintainers        FROM  ...
// to future maintainers
// to future maintainers     note0   the regex used assumes that all boolean columns end with the _yn postfix   if your boolean columns follow a different naming scheme you
// to future maintainers     note0   have to tweak the regular expression accordingly
// to future maintainers
// to future maintainers     note1   notice that special care has been taken to ensure that we only tweak the columns that preceed the FROM part  we dont want to affect anything
// to future maintainers     note1   after the FROM part if the projects involved ever get upgraded to employ efcore then you can do away with this approach by simply following
// to future maintainers     note1   the following small guide
// to future maintainers
// to future maintainers                                           https://docs.microsoft.com/en-us/ef/core/modeling/relational/data-types
// to future maintainers
public sealed class MsSqlServerHotFixerCommandInterceptor : IDbCommandInterceptor
{
    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        HotfixFaultySqlCommands(command, interceptionContext);
    }

    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        HotfixFaultySqlCommands(command, interceptionContext);
    }

    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        HotfixFaultySqlCommands(command, interceptionContext);
    }

    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
    }

    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
    }

    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
    }

    static private void HotfixFaultySqlCommands<TResult>(IDbCommand command, DbCommandInterceptionContext<TResult> interceptionContext)
    {
        if (!command.CommandText.TrimStart().StartsWith("SELECT", ignoreCase: true, culture: CultureInfo.InvariantCulture))
            return;

        command.CommandText = BooleanColumnSpotter.Replace(command.CommandText, "CAST ($1 AS BIT)");
    }

    static private readonly Regex BooleanColumnSpotter = new Regex(@"((?<!\s+FROM\s+.*)([[][a-zA-Z0-9_]+?[]][.])?[[][a-zA-Z0-9_]+[]])(?=\s+AS\s+[[][a-zA-Z0-9_]+?_YN[]])", RegexOptions.IgnoreCase);
}

E alcuni test rapidi:

{
  // -- DROP TABLE FOOBAR;
  // 
  // CREATE TABLE FOOBAR (
  // FB_ID NUMERIC(11,0) PRIMARY KEY,
  // FB_YN NUMERIC(1,0) NOT NULL,
  // FB2_YN NUMERIC(1,0) NULL
  // );
  // 
  // INSERT INTO FOOBAR (FB_ID, FB_YN, FB2_YN)
  // VALUES             (1, 0, 0);
  // 
  // INSERT INTO FOOBAR (FB_ID, FB_YN, FB2_YN)
  // VALUES             (2, 1, 1);
  // 
  // INSERT INTO FOOBAR (FB_ID, FB_YN, FB2_YN)
  // VALUES             (3, 1, null);

  var mainDatabaseContext = new YourContext(...);

  var test1 = mainDatabaseContext.Set<FOOBAR>().ToList();
  var test2 = mainDatabaseContext.Set<FOOBAR>().Take(1).ToList();
  var test3 = mainDatabaseContext.Set<FOOBAR>().Take(10).ToList();
  var test4 = mainDatabaseContext.Set<FOOBAR>().FirstOrDefault();
  var test5 = mainDatabaseContext.Set<FOOBAR>().OrderBy(x => x.FB_ID).ToList();
  var test6 = mainDatabaseContext.Set<FOOBAR>().Take(10).Except(mainDatabaseContext.Set<FOOBAR>().Take(10)).SingleOrDefault();
  var test7 = mainDatabaseContext.Set<FOOBAR>().Where(x => x.FB_ID == 1).ToList();
  var test8 = mainDatabaseContext.Set<FOOBAR>().Where(x => x.FB_YN).ToList();
  var test9 = (
      from x in mainDatabaseContext.Set<FOOBAR>()
      join y in mainDatabaseContext.Set<FOOBAR>() on x.FB_ID equals y.FB_ID into rightSide
      from r in rightSide.DefaultIfEmpty()
      select r
  ).ToList();

  var test10 = (
          from x in mainDatabaseContext.Set<FOOBAR>()
          join y in mainDatabaseContext.Set<FOOBAR>() on new {x.FB_YN, FB_YN2 = x.FB2_YN} equals new {y.FB_YN, FB_YN2 = y.FB2_YN} into rightSide
          from r in rightSide.DefaultIfEmpty()
          select r
      ).ToList();
}