Add map_nulls_to_nil configuration

[JustinG721]

The odbc used by Snowflex driver will, by default, return :null for empty values in a query rather than nil, a value native to Elixir. This pull requests adds translation of :null to :nil along with configuration to disable this feature if desired.

[jeremyowensboggs]

Should this default to false to preserve current behavior and not introduce a breaking change?

[Ch4s3]

yes, it should

[zbarnes757]

I think rather than an application-level setting, this can be an option on Snowflex.Connection. We can then extend the Snowflex.sql_query/3 and Snowflex.param_query/4 to accept a keyword list of options as the last argument. That will allow us to easily implement #8 later.

Also, please be sure to update the changelog with the new feature. 🙂

[DavidAntaramian]

I think rather than an application level setting, this can be a option on Snowflex.Connection. We can then extend the Snowflex.sql_query/3 and Snowflex.param_query/4 to accept a keyword list of options as the last argument. That will allow us to easily implement #8 later.

Should it perhaps be both?

I can foresee library consumers not wanting to set the option for each query, so allowing them to set it as a default would be good.

[zbarnes757]

I can foresee library consumers not wanting to set the option for each query, so allowing them to set it as a default would be good.

I am thinking of an option you can set like:

defmodule MyApp.Snowflake.Warehouse do
  use Snowflex.Connection,
    otp_app: :my_app,
    timeout: :timer.minutes(20),
    map_nulls_to_nil?: true
end

Then if the user wants to change per request, they can override with

Warehouse.execute(query, map_nulls_to_nil?: false, timeout: :timer.seconds(1))

[JustinG721]

I can foresee library consumers not wanting to set the option for each query, so allowing them to set it as a default would be good.

I am thinking of an option you can set like:

defmodule MyApp.Snowflake.Warehouse do
  use Snowflex.Connection,
    otp_app: :my_app,
    timeout: :timer.minutes(20),
    map_nulls_to_nil?: true
end

Then if the user wants to change per request, they can override with

Warehouse.execute(query, map_nulls_to_nil?: false, timeout: :timer.seconds(1))

Good suggestion @zbarnes757 , I decided to add the configuration to the using block of the connection and replace the timeout variable with a keyword list argument containing the timeout and my map_nulls_to_nil? variable. The default has also been updated to false to maintain current functionality.

[zbarnes757]

just change the order of the function arguments