Always interpret dates as UTC / database local time

This avoids dates traveling across 24 hour boundaries, with no good way
to avoid. I think most people would expect this behavior, rather than
the previous behavior.

Fixes #398

Author: jimhester

NEWS.md

@@ -14,6 +14,7 @@
 * `dbBind()` and `dbFetch()` now support multiple result sets (@vkapartzianis, #234)
 * `dbFetch()` now verifies that `n` is a valid input.
 * `dbQuoteIdentifier()` now uses the input names (if any).
+* Dates are now always interpreted as being in the database's local time zone, regardless of the `timezone` parameter (#398)
 
 # odbc 1.2.3
 

src/odbc_result.cpp

@@ -355,7 +355,7 @@ nanodbc::date odbc_result::as_date(double value) {
   using namespace std::chrono;
   auto utc_time = system_clock::from_time_t(static_cast<std::time_t>(value));
 
-  auto civil_time = cctz::convert(utc_time, c_->timezone());
+  auto civil_time = cctz::convert(utc_time, cctz::utc_time_zone());
   dt.day = civil_time.day();
   dt.month = civil_time.month();
   dt.year = civil_time.year();
@@ -547,8 +547,8 @@ void odbc_result::add_classes(
     case raw_t:
       // FIXME: Use new_blob()
       x.attr("ptype") = Rcpp::RawVector::create();
-      x.attr("class") =
-          Rcpp::CharacterVector::create("blob", "vctrs_list_of", "vctrs_vctr", "list");
+      x.attr("class") = Rcpp::CharacterVector::create(
+          "blob", "vctrs_list_of", "vctrs_vctr", "list");
       break;
     default:
       break;

tests/testthat/test-SQLServer.R

@@ -147,4 +147,10 @@ test_that("SQLServer", {
     received <- DBI::dbReadTable(con, tblName)
     expect_equal(values, received)
   })
+
+  test_that("dates should always be interpreted in the system time zone (#398)", {
+    con <- DBItest:::connect(DBItest:::get_default_context(), timezone = "America/Chicago")
+    res <- dbGetQuery(con, "SELECT ?", params = as.Date("2019-01-01"))
+    expect_equal(res[[1]], "2019-01-01")
+  })
 })