Merge pull request #37 from GlobalFishingWatch/update-tagblock

Add update_tagblock()

ais_tools/__init__.py

@@ -2,7 +2,7 @@
 Tools for managing AIS messages
 """
 
-__version__ = 'v0.1.5.dev1'
+__version__ = 'v0.1.5.dev2'
 __author__ = 'Paul Woods'
 __email__ = '[email protected]'
 __source__ = 'https://github.com/GlobalFishingWatch/ais-tools'

ais_tools/tagblock.py

@@ -152,3 +152,11 @@ def decode_tagblock(tagblock_str, validate_checksum=False):
             raise DecodeError('Unable to decode tagblock string')
 
     return fields
+
+
+def update_tagblock(nmea, **kwargs):
+    tagblock_str, nmea = split_tagblock(nmea)
+    tagblock = decode_tagblock(tagblock_str)
+    tagblock.update(kwargs)
+    tagblock_str = encode_tagblock(**tagblock)
+    return join_tagblock(tagblock_str, nmea)

tests/test_tagblock.py

@@ -115,3 +115,16 @@ def test_decode_tagblock_invalid_checksum(tagblock_str):
 def test_decode_tagblock_invalid(tagblock_str):
     with pytest.raises(DecodeError, match='Unable to decode tagblock string'):
         tagblock.decode_tagblock(tagblock_str, validate_checksum=False)
+
+
+@pytest.mark.parametrize("tagblock_str,new_fields,expected", [
+    ('!AIVDM', {'q':123}, '\\q:123*7B\\!AIVDM'),
+    ('\\!AIVDM', {'q':123}, '\\q:123*7B\\!AIVDM'),
+    ('\\s:00*00\\!AIVDM', {'tagblock_station':99}, '\\s:99*49\\!AIVDM'),
+    ('\\s:00*00\\!AIVDM\\s:00*00\\!AIVDM', {'tagblock_station':99}, '\\s:99*49\\!AIVDM\\s:00*00\\!AIVDM'),
+    ('\\c:123456789*68\\!AIVDM', {}, '\\c:123456789*68\\!AIVDM'),
+    ('\\c:123456789*68\\!AIVDM', {'tagblock_station':99}, '\\c:123456789,s:99*0D\\!AIVDM'),
+    ('\\c:123456789*68\\!AIVDM', {'q':123}, '\\c:123456789,q:123*3F\\!AIVDM'),
+])
+def test_update_tagblock(tagblock_str, new_fields, expected):
+    assert expected == tagblock.update_tagblock(tagblock_str, **new_fields)