Preserve DateTime microsecond precision

Makefile

@@ -3,6 +3,14 @@ SOURCES=$(shell find src -type f)
 build: $(shell find src -type f)
 	nimble build
 
+unittest:
+	nimble unittest
+.PHONY: unittest
+
+integrationtest:
+	nimble integrationtest
+.PHONY: integrationtest
+
 docs: $(shell find src -type f)
 	nim doc --project --index:on --git.url:https://github.com/jdbernard/fiber-orm --outdir:docs src/fiber_orm
 	nim rst2html --outdir:docs README.rst

fiber_orm.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "4.2.0"
+version       = "4.3.0"
 author        = "Jonathan Bernard"
 description   = "Lightweight Postgres ORM for Nim."
 license       = "GPL-3.0"
@@ -12,3 +12,12 @@ srcDir        = "src"
 
 requires @["nim >= 1.4.0", "uuids"]
 requires "namespaced_logging >= 2.0.2"
+
+
+# Tasks
+
+task unittest, "Runs the unit test suite.":
+  exec "nim c -r --path:src tests/test_datetime"
+
+task integrationtest, "Runs the PostgreSQL integration test suite.":
+  exec "nim c -r --path:src tests/test_datetime_postgres"

src/fiber_orm/util.nim

@@ -26,12 +26,12 @@ type
 const ISO_8601_FORMATS = @[
   "yyyy-MM-dd'T'HH:mm:ssz",
   "yyyy-MM-dd'T'HH:mm:sszzz",
+  "yyyy-MM-dd'T'HH:mm:ss'.'ffffffzzz",
   "yyyy-MM-dd'T'HH:mm:ss'.'fffzzz",
-  "yyyy-MM-dd'T'HH:mm:ss'.'ffffzzz",
   "yyyy-MM-dd HH:mm:ssz",
   "yyyy-MM-dd HH:mm:sszzz",
-  "yyyy-MM-dd HH:mm:ss'.'fffzzz",
-  "yyyy-MM-dd HH:mm:ss'.'ffffzzz"
+  "yyyy-MM-dd HH:mm:ss'.'ffffffzzz",
+  "yyyy-MM-dd HH:mm:ss'.'fffzzz"
 ]
 
 proc parseIso8601(val: string): DateTime =
@@ -121,32 +121,41 @@ proc parsePGDatetime*(val: string): DateTime =
   const PG_TIMESTAMP_FORMATS = [
     "yyyy-MM-dd HH:mm:ss",
     "yyyy-MM-dd'T'HH:mm:ss",
+    "yyyy-MM-dd HH:mm:ssz",
+    "yyyy-MM-dd'T'HH:mm:ssz",
     "yyyy-MM-dd HH:mm:sszz",
     "yyyy-MM-dd'T'HH:mm:sszz",
+    "yyyy-MM-dd HH:mm:sszzz",
+    "yyyy-MM-dd'T'HH:mm:sszzz",
     "yyyy-MM-dd HH:mm:ss'.'fff",
     "yyyy-MM-dd'T'HH:mm:ss'.'fff",
     "yyyy-MM-dd HH:mm:ss'.'fffzz",
     "yyyy-MM-dd'T'HH:mm:ss'.'fffzz",
     "yyyy-MM-dd HH:mm:ss'.'fffzzz",
     "yyyy-MM-dd'T'HH:mm:ss'.'fffzzz",
+    "yyyy-MM-dd HH:mm:ss'.'ffffff",
+    "yyyy-MM-dd'T'HH:mm:ss'.'ffffff",
+    "yyyy-MM-dd HH:mm:ss'.'ffffffz",
+    "yyyy-MM-dd'T'HH:mm:ss'.'ffffffz",
+    "yyyy-MM-dd HH:mm:ss'.'ffffffzz",
+    "yyyy-MM-dd'T'HH:mm:ss'.'ffffffzz",
+    "yyyy-MM-dd HH:mm:ss'.'ffffffzzz",
+    "yyyy-MM-dd'T'HH:mm:ss'.'ffffffzzz",
   ]
 
   var correctedVal = val;
 
-  # The Nim `times#format` function only recognizes 3-digit millisecond values
-  # but PostgreSQL will sometimes send 1-2 digits, truncating any trailing 0's,
-  # or sometimes provide more than three digits of preceision in the millisecond value leading
-  # to values like `2020-01-01 16:42.3+00` or `2025-01-06 00:56:00.9007+00`.
-  # This cannot currently be parsed by the standard times format as it expects
-  # exactly three digits for millisecond values. So we have to detect this and
-  # coerce the millisecond value to exactly 3 digits.
-  let PG_PARTIAL_FORMAT_REGEX = re"(\d{4}-\d{2}-\d{2}( |'T')\d{2}:\d{2}:\d{2}\.)(\d+)(\S+)?"
+  # Nim's time parser requires a fixed number of fractional digits for each
+  # format pattern. PostgreSQL emits between one and six digits, omitting
+  # trailing zeroes. Normalize the fraction to six digits so parsing retains
+  # PostgreSQL's full microsecond precision.
+  let PG_PARTIAL_FORMAT_REGEX = re"(\d{4}-\d{2}-\d{2}( |T)\d{2}:\d{2}:\d{2}\.)(\d+)(\S+)?"
   let match = val.match(PG_PARTIAL_FORMAT_REGEX)
 
   if match.isSome:
     let c = match.get.captures
-    if c.toSeq.len == 2: correctedVal = c[0] & alignLeft(c[2], 3, '0')[0..2]
-    else: correctedVal = c[0] & alignLeft(c[2], 3, '0')[0..2] & c[3]
+    correctedVal = c[0] & alignLeft(c[2], 6, '0')[0..5]
+    if 3 in c: correctedVal &= c[3]
 
   var errStr = ""
 

tests/test_datetime.nim

@@ -0,0 +1,53 @@
+import std/[times, unittest]
+
+import fiber_orm/util
+
+proc utcDateTime(nanosecond: NanosecondRange): DateTime =
+  dateTime(
+    2026, mAug, 26, 14, 32, 10, nanosecond,
+    utc())
+
+suite "PostgreSQL DateTime conversion":
+  test "formats DateTime values with microsecond precision":
+    check dbFormat(utcDateTime(123_457_000)) ==
+      "2026-08-26T14:32:10.123457Z"
+
+  test "parses whole-second, millisecond, and microsecond values":
+    let cases = [
+      ("2026-08-26 14:32:10+00", 0),
+      ("2026-08-26 14:32:10.123+00", 123_000_000),
+      ("2026-08-26 14:32:10.9007+00", 900_700_000),
+      ("2026-08-26 14:32:10.12345+00", 123_450_000),
+      ("2026-08-26 14:32:10.123457+00", 123_457_000),
+    ]
+
+    for (value, expectedNanosecond) in cases:
+      let parsed = parsePGDatetime(value)
+      check parsed.nanosecond == expectedNanosecond
+      check parsed.utc.format("yyyy-MM-dd'T'HH:mm:ss") ==
+        "2026-08-26T14:32:10"
+
+  test "preserves supported separators and timezone representations":
+    let timezoneCases = [
+      "2026-08-26 14:32:10+00",
+      "2026-08-26T14:32:10+00",
+      "2026-08-26T14:32:10+00:00",
+      "2026-08-26 14:32:10.123+00",
+      "2026-08-26T14:32:10.123457+00:00",
+      "2026-08-26T14:32:10.123457Z",
+    ]
+
+    for value in timezoneCases:
+      check parsePGDatetime(value).utc.format("yyyy-MM-dd'T'HH:mm:ss") ==
+        "2026-08-26T14:32:10"
+
+    let localCases = [
+      "2026-08-26 14:32:10",
+      "2026-08-26T14:32:10",
+      "2026-08-26 14:32:10.1",
+      "2026-08-26T14:32:10.12",
+    ]
+
+    for value in localCases:
+      check parsePGDatetime(value).format("yyyy-MM-dd'T'HH:mm:ss") ==
+        "2026-08-26T14:32:10"

tests/test_datetime_postgres.nim

@@ -0,0 +1,30 @@
+import std/[os, times, unittest]
+import db_connector/[db_common, db_postgres]
+
+import fiber_orm/util
+
+proc utcDateTime(nanosecond: NanosecondRange): DateTime =
+  dateTime(
+    2026, mAug, 26, 14, 32, 10, nanosecond,
+    utc())
+
+let connectionString = getEnv("FIBER_ORM_TEST_DB")
+if connectionString.len == 0:
+  quit "FIBER_ORM_TEST_DB must contain a PostgreSQL connection string"
+
+suite "PostgreSQL DateTime round trips":
+  test "preserves whole-second, millisecond, and microsecond values":
+    let db = db_postgres.open("", "", "", connectionString)
+    defer: db.close()
+    db.exec(sql"SET TIME ZONE 'UTC'")
+
+    for expected in [
+      utcDateTime(0),
+      utcDateTime(123_000_000),
+      utcDateTime(123_457_000),
+    ]:
+      let dbValue = db.getValue(
+        sql"SELECT ?::timestamp with time zone",
+        dbFormat(expected))
+      let actual = parsePGDatetime(dbValue)
+      check actual.toTime == expected.toTime