fix: DateOnlyCoder uses regex to strip time + timezone (#287)

For DateOnlyCoding, we assume the device local timezone when parsing.
For this, we now strip out everything except for the date from the input
string, and only then run the formatter. This produces a naive Date
object in the local timezone. When we send it back to the backend, we
only format the date component, so roundtripping should be safe in all
cases. 🤞

See #286

Author: paulgessinger

Common/Package.swift

@@ -8,7 +8,7 @@ let package = Package(
     name: "Common",
     platforms: [
         .iOS(.v17),
-        .macOS(.v12),
+        .macOS(.v13),
     ],
     products: [
         .library(

Common/Sources/Common/DateOnlyCoder.swift

@@ -8,6 +8,8 @@
 import Foundation
 import MetaCodable
 
+import os
+
 public struct DateOnlyCoder: HelperCoder {
     public typealias Coded = Date
 
@@ -17,36 +19,26 @@ public struct DateOnlyCoder: HelperCoder {
         let container = try decoder.singleValueContainer()
         let dateStr = try container.decode(String.self)
 
-        let df = DateFormatter()
-        df.timeZone = TimeZone(secondsFromGMT: 0)
-        df.dateFormat = "yyyy-MM-dd"
+        let ex = /(\d{4}-\d{2}-\d{2}).*/
 
-        if let res = df.date(from: dateStr) {
-            return res
+        guard let match = try? ex.wholeMatch(in: dateStr) else {
+            throw DateDecodingError.invalidDate(string: dateStr)
         }
 
-        let iso = ISO8601DateFormatter()
-        iso.formatOptions = [
-            .withInternetDateTime,
-            .withFractionalSeconds,
-        ]
-        if let res = iso.date(from: dateStr) {
-            return res
-        }
+        let df = DateFormatter()
+        df.dateFormat = "yyyy-MM-dd"
 
-        iso.formatOptions = [.withInternetDateTime]
-        if let res = iso.date(from: dateStr) {
-            return res
+        guard let res = df.date(from: String(match.1)) else {
+            throw DateDecodingError.invalidDate(string: dateStr)
         }
 
-        throw DateDecodingError.invalidDate(string: dateStr)
+        return res
     }
 
     public func encode(_ value: Coded, to encoder: Encoder) throws {
         var container = encoder.singleValueContainer()
 
         let formatter = DateFormatter()
-        formatter.timeZone = TimeZone(secondsFromGMT: 0)
         formatter.dateFormat = "yyyy-MM-dd"
 
         try container.encode(formatter.string(from: value))

Common/Tests/CommonTests/DateOnlyCoderTest.swift

@@ -36,23 +36,41 @@ func testDateOnlyCoderDecode() throws {
     let decoder = JSONDecoder()
 
     var decoded = try decoder.decode(TestStruct.self, from: dateOnly)
+    print(decoded)
 
     let exp = try #require(Calendar.current.date(from: DateComponents(year: 2023, month: 12, day: 4, hour: 0, minute: 0, second: 0)))
     #expect(decoded.created == exp)
 
-    let tz = TimeZone(secondsFromGMT: 60 * 60)!
     let dateTime = try #require(#"{"created":"2023-12-04T09:10:24+01:00"}"#.data(using: .utf8))
 
     decoded = try decoder.decode(TestStruct.self, from: dateTime)
 
-    var cal = Calendar.current
-    cal.timeZone = tz
+    let cal = Calendar.current
     let components = cal.dateComponents([.year, .month, .day, .hour, .minute, .second], from: decoded.created)
 
     #expect(components.year == 2023)
     #expect(components.month == 12)
     #expect(components.day == 4)
-    #expect(components.hour == 9)
-    #expect(components.minute == 10)
-    #expect(components.second == 24)
+    #expect(components.hour == 0)
+    #expect(components.minute == 0)
+    #expect(components.second == 0)
+}
+
+@Test("Arbitrary timezones get stripped out", arguments: 1 ... 10)
+func testArbitraryTimezonesGetStrippedOut(offset: Int) throws {
+    let dateOnly = try #require("{\"created\":\"2028-11-02T00:00:00+0\(offset):00\"}".data(using: .utf8))
+
+    let decoder = JSONDecoder()
+
+    let decoded = try decoder.decode(TestStruct.self, from: dateOnly)
+
+    let cal = Calendar.current
+    let components = cal.dateComponents([.year, .month, .day, .hour, .minute, .second], from: decoded.created)
+
+    #expect(components.year == 2028)
+    #expect(components.month == 11)
+    #expect(components.day == 2)
+    #expect(components.hour == 0)
+    #expect(components.minute == 0)
+    #expect(components.second == 0)
 }

DataModel/Tests/DataModelTests/DocumentModelTest.swift

@@ -26,7 +26,7 @@ struct DocumentModelTest {
         #expect(document.title == "Quittung")
         #expect(document.tags == [1, 2, 3])
 
-        #expect(dateApprox(document.created, datetime(year: 2024, month: 12, day: 21, hour: 0, minute: 0, second: 0, tz: TimeZone(secondsFromGMT: 0)!)))
+        #expect(dateApprox(document.created, datetime(year: 2024, month: 12, day: 21, hour: 0, minute: 0, second: 0)))
         #expect(try dateApprox(#require(document.modified), datetime(year: 2024, month: 12, day: 21, hour: 21, minute: 41, second: 49, tz: tz)))
         #expect(try dateApprox(#require(document.added), datetime(year: 2024, month: 12, day: 21, hour: 21, minute: 26, second: 36, tz: tz)))
 
@@ -53,7 +53,7 @@ struct DocumentModelTest {
         #expect(document.title == "Quittung")
         #expect(document.tags == [1, 2, 3])
 
-        #expect(dateApprox(document.created, datetime(year: 2024, month: 12, day: 21, hour: 0, minute: 0, second: 0, tz: tz)))
+        #expect(dateApprox(document.created, datetime(year: 2024, month: 12, day: 21, hour: 0, minute: 0, second: 0)))
         #expect(try dateApprox(#require(document.modified), datetime(year: 2024, month: 12, day: 21, hour: 21, minute: 41, second: 49, tz: tz)))
         #expect(try dateApprox(#require(document.added), datetime(year: 2024, month: 12, day: 21, hour: 21, minute: 26, second: 36, tz: tz)))
 

current_changelog.txt

@@ -0,0 +1 @@
+- Fix timezone conversion in document created date: on versions below 2.16.0 of Paperless-ngx, the timezone was incorrectly set and resulted in the date shifting when saving.