Inferred reference types assumed to be non-nullable about fsharp.data.sqlclient

[dmitry-a-morozov]

@danielrbradley The type provider currently supports nullable input parameters by mapping them to optional args for AsyncExecute/Execute.
Be careful with the specific example you gave - you cannot have unbound variable with same name (@bitfilter) more than once in side single T-SQL batch. The workaround is to use intermediate variable inside script like
DECLARE @bitFilterCopy AS BIT = @bitfilter
SELECT * FROM x WHERE @bitFilterCopy IS NULL OR (BitCol = @bitFilterCopy)

[dmitry-a-morozov]

@danielrbradley I take my previous comment back. There is no way to specify nullable input params. Mostly because meta-info stored procedure sys.sp_describe_undeclared_parameters TP relies upon doesn't support it.
More to that, even for stored procedure there no reasonable way to get default values for parameters.

[danielrbradley]

@dmitry-a-morozov I assumed there was a good reason as to why it's not currently implemented. However, might it be possible to change the implementation, or provide an option when defining the type provider (similar to the SingleRow = true), to make it assume that all parameters found could be nullable, perhaps an option like AllowNullParameters?

[dmitry-a-morozov]

@danielrbradley I'm kind of back working on small fixes for the SqlCommandProvider. Do you still think AllowNullParameters feature will be valuable?

[jackfoxy]

as in SELECT * FROM tbMyTable WHERE myTableColumn = @myTableColumn and I want the parameter to be null? In that case I would say "yes", however perhaps it would be more F# type compliant if we could assign the myTableColumn to None.

[dmitry-a-morozov]

Ok. I will start working on this.

[dmitry-a-morozov]

Fixed. Release 1.1.24.

[dsevastianov]

@danielrbradley SqlProgrammabilityProvider now supports default parameters and nullable input-output parameters for Stored Procedures and Table-Valued User-Defined Functions.
And of course SqlCommandProvider now supports AllParametersOptional.

Also, there is a simple workaround for the issue with SqlCommandProvider not accepting duplicate usage of variables in SQL as mentioned by @dmitry-a-morozov (at least in this particular case):

 SELECT * FROM x WHERE BitCol = ISNULL(@bitFilter, BitCol)