def decode_marc(
self,
marc,
to_unicode=True,
force_utf8=False,
hide_utf8_warnings=False,
utf8_handling="strict",
encoding="iso8859-1",
):
"""Populate the object based on the `marc`` record in transmission format.
The Record constructor actually uses decode_marc() behind the scenes when you
pass in a chunk of MARC data to it.
"""
# extract record leader
self.leader = marc[0:LEADER_LEN].decode("ascii")
if len(self.leader) != LEADER_LEN:
raise RecordLeaderInvalid
if self.leader[9] == "a" or self.force_utf8:
encoding = "utf-8"
# extract the byte offset where the record data starts
base_address = int(marc[12:17])
if base_address <= 0:
raise BaseAddressNotFound
if base_address >= len(marc):
raise BaseAddressInvalid
# extract directory, base_address-1 is used since the
# director ends with an END_OF_FIELD byte
directory = marc[LEADER_LEN:base_address - 1].decode("ascii")
# determine the number of fields in record
if len(directory) % DIRECTORY_ENTRY_LEN != 0:
raise RecordDirectoryInvalid
field_total = len(directory) / DIRECTORY_ENTRY_LEN
# add fields to our record using directory offsets
field_count = 0
while field_count < field_total:
entry_start = field_count * DIRECTORY_ENTRY_LEN
entry_end = entry_start + DIRECTORY_ENTRY_LEN
entry = directory[entry_start:entry_end]
entry_tag = entry[0:3]
entry_length = int(entry[3:7])
entry_offset = int(entry[7:12])
entry_data = marc[base_address + entry_offset:base_address +
entry_offset + entry_length - 1]
# assume controlfields are numeric; replicates ruby-marc behavior
if entry_tag < "010" and entry_tag.isdigit():
if to_unicode:
field = Field(tag=entry_tag,
data=entry_data.decode(encoding))
else:
field = RawField(tag=entry_tag, data=entry_data)
else:
subfields = list()
subs = entry_data.split(SUBFIELD_INDICATOR.encode("ascii"))
# The MARC spec requires there to be two indicators in a
# field. However experience in the wild has shown that
# indicators are sometimes missing, and sometimes there
# are too many. Rather than throwing an exception because
# we can't find what we want and rejecting the field, or
# barfing on the whole record we'll try to use what we can
# find. This means missing indicators will be recorded as
# blank spaces, and any more than 2 are dropped on the floor.
first_indicator = second_indicator = " "
subs[0] = subs[0].decode("ascii")
if len(subs[0]) == 0:
logging.warning("missing indicators: %s", entry_data)
first_indicator = second_indicator = " "
elif len(subs[0]) == 1:
logging.warning("only 1 indicator found: %s", entry_data)
first_indicator = subs[0][0]
second_indicator = " "
elif len(subs[0]) > 2:
logging.warning("more than 2 indicators found: %s",
entry_data)
first_indicator = subs[0][0]
second_indicator = subs[0][1]
else:
first_indicator = subs[0][0]
second_indicator = subs[0][1]
for subfield in subs[1:]:
skip_bytes = 1
if len(subfield) == 0:
continue
try:
code = subfield[0:1].decode("ascii")
except UnicodeDecodeError:
warnings.warn(BadSubfieldCodeWarning())
code, skip_bytes = normalize_subfield_code(subfield)
data = subfield[skip_bytes:]
if to_unicode:
if self.leader[9] == "a" or force_utf8:
data = data.decode("utf-8", utf8_handling)
elif encoding == "iso8859-1":
data = marc8_to_unicode(data, hide_utf8_warnings)
else:
data = data.decode(encoding)
subfields.append(code)
subfields.append(data)
if to_unicode:
field = Field(
tag=entry_tag,
indicators=[first_indicator, second_indicator],
subfields=subfields,
)
else:
field = RawField(
tag=entry_tag,
indicators=[first_indicator, second_indicator],
subfields=subfields,
)
self.add_field(field)
field_count += 1
if field_count == 0:
raise NoFieldsFound
def decode_marc(self,
marc,
to_unicode=True,
force_utf8=False,
hide_utf8_warnings=False,
utf8_handling='ignore'):
self.leader = marc[0:LEADER_LEN]
if len(self.leader) != LEADER_LEN:
raise RecordLeaderInvalid
if self.leader[9] == 'a' or self.force_utf8:
encoding = 'utf-8'
else:
encoding = 'iso8859-1'
base_address = int(marc[12:17])
if base_address <= 0:
raise BaseAddressNotFound
if base_address >= len(marc):
raise BaseAddressInvalid
directory = marc[LEADER_LEN:base_address - 1]
if len(directory) % DIRECTORY_ENTRY_LEN != 0:
raise RecordDirectoryInvalid
field_total = len(directory) / DIRECTORY_ENTRY_LEN
field_count = 0
while field_count < field_total:
entry_start = field_count * DIRECTORY_ENTRY_LEN
entry_end = entry_start + DIRECTORY_ENTRY_LEN
entry = directory[entry_start:entry_end]
entry_tag = entry[0:3]
entry_length = int(entry[3:7])
entry_offset = int(entry[7:12])
entry_data = marc[base_address + entry_offset:base_address +
entry_offset + entry_length - 1]
if entry_tag < '010' and entry_tag.isdigit():
if to_unicode:
field = Field(tag=entry_tag, data=entry_data)
else:
field = RawField(tag=entry_tag, data=entry_data)
else:
subfields = list()
subs = entry_data.split(SUBFIELD_INDICATOR)
#subs = entry_data.split(SUBFIELD_INDICATOR.encode().decode('ascii', errors='ignore'))
first_indicator = second_indicator = ' '
#subs[0] = subs[0].decode('ascii')
if len(subs[0]) == 0:
logging.warning("missing indicators: %s", entry_data)
first_indicator = second_indicator = ' '
elif len(subs[0]) == 1:
logging.warning("only 1 indicator found: %s", entry_data)
first_indicator = subs[0][0]
second_indicator = ' '
elif len(subs[0]) > 2:
logging.warning("more than 2 indicators found: %s",
entry_data)
first_indicator = subs[0][0]
second_indicator = subs[0][1]
else:
first_indicator = subs[0][0]
second_indicator = subs[0][1]
for subfield in subs[1:]:
if len(subfield) == 0:
continue
code = subfield[0:1]
data = subfield[1:]
if to_unicode:
if self.leader[9] == 'a' or force_utf8:
data = data.encode().decode('utf-8', utf8_handling)
else:
data = marc8_to_unicode(data, hide_utf8_warnings)
subfields.append(code)
subfields.append(data)
if to_unicode:
field = Field(
tag=entry_tag,
indicators=[first_indicator, second_indicator],
subfields=subfields)
else:
field = RawField(
tag=entry_tag,
indicators=[first_indicator, second_indicator],
subfields=subfields)
self.add_field(field)
field_count += 1
if field_count == 0:
raise NoFieldsFound
return self