def decode_msg(self, primitive, assoc=None):
"""Converts P-DATA primitives into a ``DIMSEMessage`` sub-class.
Decodes the data from the P-DATA service primitive (which
may contain the results of one or more P-DATA-TF PDUs) into the
:attr:`~DIMSEMessage.command_set` and :attr:`~DIMSEMessage.data_set`
attributes. Also sets the :attr:`~DIMSEMessage.context_id` and
:attr:`~DIMSEMessage.encoded_command_set` attributes of the
``DIMSEMessage`` sub-class object.
Parameters
----------
primitive : pdu_primitives.P_DATA
The P-DATA service primitive to be decoded into a DIMSE message.
assoc : association.Association, optional
The association processing the message. This is required when:
* :attr:`~pynetdicom._config.STORE_RECV_CHUNKED_DATASET` is
``True``
* The P-DATA primitive contains part of a C-STORE-RQ message
In this case the association is consulted for its accepted
transfer syntax, which is included in the File Meta Information
of the stored dataset.
Returns
-------
bool
``True`` when the DIMSE message is completely decoded, ``False``
otherwise.
References
----------
* DICOM Standard, Part 8, :dcm:`Annex E<part08/chapter_E.html>`
"""
# Make sure this is a P-DATA primitive
if primitive.__class__ != P_DATA or primitive is None:
return False
for (context_id, data) in primitive.presentation_data_value_list:
# The first byte of the P-DATA is the Message Control Header
# See Part 8, Annex E.2
# The standard says that only the significant bits (ie the last
# two) should be checked
# xxxxxx00 - Message Dataset information, not the last fragment
# xxxxxx01 - Command information, not the last fragment
# xxxxxx10 - Message Dataset information, the last fragment
# xxxxxx11 - Command information, the last fragment
control_header_byte = data[0]
# LOGGER.debug('Control header byte %s', control_header_byte)
#print(f'Control header byte {control_header_byte}')
# COMMAND SET
# P-DATA fragment contains Command Set information
# (control_header_byte is xxxxxx01 or xxxxxx11)
if control_header_byte & 1:
# The command set may be spread out over a number
# of fragments and P-DATA primitives and we need to remember
# the elements from previous fragments, hence the
# encoded_command_set class attribute
# This adds all the command set data to the class object
self.encoded_command_set.write(data[1:])
# The final command set fragment (xxxxxx11) has been added
# so decode the command set
if control_header_byte & 2:
# Presentation Context ID
# Set this now as must only be one final command set
# fragment and command set must always be present
self.context_id = context_id
# Command Set is always encoded Implicit VR Little Endian
# decode(dataset, is_implicit_VR, is_little_endian)
# pylint: disable=attribute-defined-outside-init
self.command_set = decode(self.encoded_command_set, True,
True)
# Determine which DIMSE Message class to use
self.__class__ = (
_MESSAGE_TYPES[self.command_set.CommandField][1])
# Determine if a Data Set is present by checking for
# (0000, 0800) CommandDataSetType US 1. If the value is
# 0x0101 no dataset present, otherwise one is.
if self.command_set.CommandDataSetType == 0x0101:
# By returning True we're indicating that the message
# has been completely decoded
return True
# Data Set is present
if (_config.STORE_RECV_CHUNKED_DATASET
and isinstance(self, C_STORE_RQ)):
# delete=False is a workaround for Windows
# Setting delete=True prevents us from re-opening
# the file after it is opened by NamedTemporaryFile
# below.
self._data_set_file = NamedTemporaryFile(delete=False,
mode="wb",
suffix=".dcm")
self._data_set_path = Path(self._data_set_file.name)
# Write the File Meta
self._data_set_file.write(b'\x00' * 128)
self._data_set_file.write(b'DICM')
cs = self.command_set
cx = assoc._accepted_cx[context_id]
write_file_meta_info(
self._data_set_file,
create_file_meta(
sop_class_uid=cs.AffectedSOPClassUID,
sop_instance_uid=cs.AffectedSOPInstanceUID,
transfer_syntax=cx.transfer_syntax[0]))
# DATA SET
# P-DATA fragment contains Data Set information
# (control_header_byte is xxxxxx00 or xxxxxx10)
else:
# As with the command set, the data set may be spread over
# a number of fragments in each P-DATA primitive and a
# number of P-DATA primitives.
if self._data_set_file:
self._data_set_file.write(data[1:])
else:
self.data_set.write(data[1:])
# The final data set fragment (xxxxxx10) has been added
if control_header_byte & 2 != 0:
# By returning True we're indicating that the message
# has been completely decoded
return True
# We return False to indicate that the message isn't yet fully decoded
return False
def file_meta(self) -> FileMetaDataset:
r"""Return a *pydicom* :class:`~pydicom.dataset.Dataset` with the
:dcm:`File Meta Information<part10/chapter_7.html#sect_7.1>` for a
C-STORE request's `Data Set`.
Contains the following File Meta Information elements:
* (0002,0000) *File Meta Information Group Length* - set as ``0``, will
be updated with the correct value during write
* (0002,0001) *File Meta Information Version* - set as ``0x0001``
* (0002,0002) *Media Storage SOP Class UID* - set from the request's
*Affected SOP Class UID*
* (0002,0003) *Media Storage SOP Instance UID* - set from the request's
*Affected SOP Instance UID*
* (0002,0010) *Transfer Syntax UID* - set from the presentation context
used to transfer the *Data Set*
* (0002,0012) *Implementation Class UID* - set using
:attr:`~pynetdicom.PYNETDICOM_IMPLEMENTATION_UID`
* (0002,0013) *Implementation Version Name* - set using
:attr:`~pynetdicom.PYNETDICOM_IMPLEMENTATION_VERSION`
Examples
--------
Add the File Meta Information to the decoded *Data Set* and save it to
the :dcm:`DICOM File Format<part10/chapter_7.html>`.
.. code-block:: python
>>> ds = event.dataset
>>> ds.file_meta = event.file_meta
>>> ds.save_as('example.dcm', write_like_original=False)
Encode the File Meta Information in a new file and append the encoded
*Data Set* to it. This skips having to decode/re-encode the *Data Set*
as in the previous example.
.. code-block:: python
>>> from pydicom.filewriter import write_file_meta_info
>>> with open('example.dcm', 'wb') as f:
... f.write(b'\x00' * 128)
... f.write(b'DICM')
... write_file_meta_info(f, event.file_meta)
... f.write(event.request.DataSet.getvalue())
Returns
-------
pydicom.dataset.Dataset
The File Meta Information suitable for use with the decoded C-STORE
request's *Data Set*.
Raises
------
AttributeError
If the corresponding event is not a C-STORE request.
"""
if not hasattr(self.request, "DataSet"):
raise AttributeError(
"The corresponding event is not a C-STORE request")
# A C-STORE request must have AffectedSOPClassUID and
# AffectedSOPInstanceUID
self.request = cast("C_STORE", self.request)
sop_class = cast(UID, self.request.AffectedSOPClassUID)
sop_instance = cast(UID, self.request.AffectedSOPInstanceUID)
return create_file_meta(
sop_class_uid=sop_class,
sop_instance_uid=sop_instance,
transfer_syntax=self.context.transfer_syntax,
)
