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Examining the Lab Message Transformation Script |
Now that you have seen how the transformations work, the next step is to examine the script that transforms the Lab Message messages. To view this transformation script:
- In the Workspace, expand the LabMessage message definition and double-click Transformation Script. The Transformation Script window appears.
Transformation Script Window
The Transformation Script window displays the Python code that performs the actual transformation.
The Python code used in this transformation script is shown below. While the size of this script may seem intimidating, the basic idea of the script is simple:
- The script uses a segment iterator object, stored in the current_segment variable, to access each segment of the message in turn. Methods and variables defined for the segment iterator object allow you to retrieve a segment and examine or modify the fields or subfields defined for the segment. The reset method enables you to go back to the start of the message and go through the segments again.
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See Segment Iterator Object for a description of the segment iterator object and its methods. | ||
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- The output variable contains the contents of the transformed message as it is being built up. Calls to current_segment.output() retrieve each segment after it has been updated; these segments are appended to output to build the transformed message.
- Other variables defined in the script enable it to retrieve information from one segment and copy it to another.
- When the transformation is completed, the transformed message is copied from the output variable to value, which is a special variable that represents the message.
The example script includes detailed comments that explain what the code is doing. The Python functions that are called from the script are defined in the VMD file's global inbound script.
# The iterator object, named current_segment in this example, is
# effectively a pointer into the list segments that are found in
# the message. We start by creating this object using the method
# input_segment_iterator() on the built-in environment object.
# Get an iterator, called current_segment, that points to the first
# segment - in an HL7 message this will always be the MSH segment.
current_segment = environment.input_segment_iterator()
# The iterator starts out on the first segment - i.e. the MSH segment. The
# apply_transform() method invokes the outbound segment scripts defined for
# the current segment. This is a reasonable technique for small sets of scripts, but
# for larger scripts, it is probably better to do all the processing explicitly here.
current_segment.apply_transform()
# The output() method of current_segment returns the flatwire - you will see that
# the script uses this method repeatedly.
output = current_segment.output()
# The move_next() method on current_segment will return false if the segment named
# is not found. This is a useful technique for dealing with optional segments.
if current_segment.move_next('PID'):
current_segment.field(1).value = "BLUE"
current_segment.field(3).subfield(0).value = "D"
current_segment.field(3).subfield(3).value = current_segment.field(3).subfield(2).value
current_segment.field(3).subfield(5).value = current_segment.field(3).subfield(2).value
current_segment.field(3).subfield(2).value = ''
Pid4 = current_segment.field(4).value
Pid4 = Pid4.replace('/', '-')
current_segment.field(4).value = Pid4
if current_segment.field(11).is_null():
current_segment.field(11).subfield(0).value = '""'
current_segment.field(11).subfield(1).value = '""'
current_segment.field(11).subfield(2).value = '""'
current_segment.field(11).subfield(3).value = '""'
current_segment.field(11).subfield(4).value = '""'
# One very handy technique with scripted transformation is to define reusable
# functions to do common tasks like cleaning up phone numbers. The function
# described below is defined in the 'Global Inbound Script.'
current_segment.field(13).value = get_clean_phone(current_segment.field(13).value)
current_segment.field(14).value = get_clean_phone(current_segment.field(14).value)
current_segment.field(18).value = "E" + current_segment.field(3).value
# This code shows how we can use a python loop to clear a range of fields
# Clear all fields after 18.
for FieldIndex in range(19, current_segment.count_of_field()):
current_segment.field(FieldIndex).clear()
output = output + current_segment.output()
if current_segment.move_next('OBR'):
# We do the NTE segments for the OBR segment before
# outputting or modifying the OBR segment because we'll need to
# clear some fields in the OBR segment.
# Here we are invoking some functions we defined in the 'Global Inbound
# Script' to keep a track of the number of NTE segments we are putting out.
# The add_NTE_segment function is just a handy re-usable function to make
# formatting these additional NTE segments easier.
resetNteCount()
nte_output = ''
nte_output = nte_output + add_NTE_segment(" " + current_segment.field(16).subfield(0).value + " "
+ current_segment.field(16).subfield(1).value + ", " + current_segment.field(16).subfield(2).value + " "
+ current_segment.field(16).subfield(3).value, "PROVIDER")
nte_output = nte_output + add_NTE_segment(current_segment.field(5).subfield(0).value, "PRIORITY")
nte_output = nte_output + add_NTE_segment(current_segment.field(15).subfield(1).value, "SPECIMEN")
nte_output = nte_output + add_NTE_segment(current_segment.field(6).subfield(0).value, "DATE_ORDERED")
Obr_15_7 = current_segment.field(15).subfield(6).value # we save this field because we nullify it later.
Obr_15_1 = current_segment.field(15).subfield(0).value
Obr_15_2 = current_segment.field(15).subfield(1).value
Obr_15_3 = current_segment.field(15).subfield(2).value
Obr_15_6 = current_segment.field(15).subfield(5).value
# clear() is a helpful method for completely clearing a field and it's children.
current_segment.field(15).clear()
current_segment.field(15).subfield(0).subfield(0).value = Obr_15_1
current_segment.field(15).subfield(0).subfield(1).value = Obr_15_2
current_segment.field(15).subfield(0).subfield(2).value = Obr_15_3
current_segment.field(15).subfield(0).subfield(5).value = Obr_15_6
current_segment.field(3).subfield(0).value = current_segment.field(20).value
current_segment.field(6).subfield(0).value = ''
current_segment.field(13).clear()
for FieldIndex in range(16, 24) :
current_segment.field(FieldIndex).clear()
for FieldIndex in range(26, current_segment.count_of_field()):
current_segment.field(FieldIndex).clear()
current_segment.field(15).subfield(6).value = ''
current_segment.field(15).subfield(7).value = ''
output = output + current_segment.output()
output = output + nte_output
if current_segment.move_next('OBX'):
output = output + add_NTE_segment(current_segment.field(14).value, "DATE_RESULTED")
# The reset() method is used to put the segment iterator back at the MSH segment.
current_segment.reset()
if current_segment.move_next('OBR'):
output = output + add_NTE_segment(Obr_15_7, "COLLECT_SAMPLE") # this field is saved from before
# we get the count of NTE segments - see Options Screen function
NteCount = count_of_NTE()
#NteCount = 99
while current_segment.move_one() and current_segment.segment_id() == 'NTE':
NteCount = NteCount + 1
current_segment.field(1).value = str(NteCount)
output = output + current_segment.output()
current_segment.reset()
while current_segment.move_next('OBX'):
current_segment.field(2).value = 'TX'
current_segment.field(3).subfield(0).value = current_segment.field(3).value + "-" + Obr_15_1
current_segment.apply_transform()
NteCount = 1
if (not current_segment.field(14).is_null()):
NteOutput = "NTE|1||DATE_RESULTED:" + current_segment.field(14).value + "\r"
NteCount = NteCount + 1
for FieldIndex in range(12, current_segment.count_of_field()):
current_segment.field(FieldIndex).clear()
output = output + current_segment.output()
output = output + NteOutput
NteOutput = ''
while current_segment.move_next('NTE'):
current_segment.field(1).subfield(0).value = str(NteCount)
NteCount = NteCount + 1
current_segment.field(3).subfield(0).value = escape_note(current_segment.field(3).value)
output = output + current_segment.output()
# All much of the same really - once you do one you can do a hundred!
value = output
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