add set date logic (#494)

snap7/util/db.py

@@ -1,6 +1,6 @@
 import re
 from collections import OrderedDict
-from datetime import datetime
+from datetime import datetime, date
 from typing import Optional, Union, Dict, Callable
 from logging import getLogger
 
@@ -46,7 +46,7 @@
     set_sint,
     set_time,
 )
-from snap7.util.setters import set_lreal
+from snap7.util.setters import set_lreal, set_date
 
 logger = getLogger(__name__)
 
@@ -540,6 +540,9 @@ def set_value(self, byte_index: Union[str, int], type_: str, value: Union[bool,
         if type_ == "TIME" and isinstance(value, str):
             return set_time(bytearray_, byte_index, value)
 
+        if type_ == "DATE" and isinstance(value, date):
+            return set_date(bytearray_, byte_index, value)
+
         raise ValueError
 
     def write(self, client: Client) -> None:

snap7/util/setters.py

@@ -1,5 +1,6 @@
 import re
 import struct
+from datetime import date
 from typing import Union
 
 from .getters import get_bool
@@ -508,3 +509,28 @@ def set_char(bytearray_: bytearray, byte_index: int, chr_: str) -> Union[ValueEr
         bytearray_[byte_index] = ord(chr_)
         return bytearray_
     raise ValueError(f"chr_ : {chr_} contains a None-Ascii value, but ASCII-only is allowed.")
+
+
+def set_date(bytearray_: bytearray, byte_index: int, date_: date) -> bytearray:
+    """Set value in bytearray to date
+    Notes:
+        Datatype `date` consists in the number of days elapsed from 1990-01-01.
+        It is stored as an int (2 bytes) in the PLC.
+    Args:
+        bytearray_: buffer to write.
+        byte_index: byte index from where to start writing.
+        date: date object
+    Examples:
+        >>> data = bytearray(2)
+        >>> snap7.util.set_date(data, 0, date(2024, 3, 27))
+        >>> data
+            bytearray(b'\x30\xd8')
+    """
+    if date_ < date(1990, 1, 1):
+        raise ValueError("date is lower than specification allows.")
+    elif date_ > date(2168, 12, 31):
+        raise ValueError("date is higher than specification allows.")
+    _days = (date_ - date(1990, 1, 1)).days
+    _bytes = struct.unpack("2B", struct.pack(">h", _days))
+    bytearray_[byte_index : byte_index + 2] = _bytes
+    return bytearray_

tests/test_util.py

@@ -597,6 +597,12 @@ def test_get_dtl(self):
         val = row["testDtl"]
         self.assertEqual(val, datetime.datetime(year=2022, month=3, day=9, hour=12, minute=34, second=45))
 
+    def test_set_date(self):
+        test_array = bytearray(_bytearray)
+        row = snap7.util.db.DB_Row(test_array, test_spec_indented, layout_offset=4)
+        row["testDate"] = datetime.date(day=28, month=3, year=2024)
+        self.assertEqual(row["testDate"], datetime.date(day=28, month=3, year=2024))
+
 
 if __name__ == "__main__":
     unittest.main()