The hl7version3 Python module is a collection of templates that generate HL7 Version 3 messages. These templates use the data stored in the XML file generated by the first VMD file that you created (which was described in Creating a VMD File To Extract Information in XML).

The main hl7version3() function calls each of these templates in turn:

def hl7version3(PlainLabDataXml):
	InMsg = xml.dom.minidom.parseString(PlainLabDataXml)
	v3 = v3Header()
	v3 += v3LabRequestHeader(time.strftime("%Y%m%d"))
	v3 += v3PatientRecordTarget(InMsg, 0, 1)
	v3 += v3HospitalTestProvider("The Performing Organisation",1)
	v3 += v3DoctorAuthor("Dr Responsible", 1)
	v3 += v3HospitalReceiver("The Requesting Organization", 1)
	v3 += v3MedicationReason(InMsg, 1)
	v3 += v3LabRequestFooter()
	return v3

Here, templates are defined for the following:

• The header for the HL7 version 3 message;
• The header for the LabRequest message that is being generated;
• The patient record;
• The hospital test provider;
• The doctor responsible for the lab request;
• The hospital that is receiving the test;
• The reason for medication;
• The footer for the LabRequest message.

The output from the templates is built into a single string variable, v3, which is returned to the Python script that called the hl7version3() function.

The following function is the template that generates the receiving hospital information:

def v3HospitalReceiver(Hospital, i):
	value = v3Indent(i)   + '<primaryInformationRecipient typeCode="PRCP">\n'
	value += v3Indent(i+1) + '<assignedOrgSDS classCode="ASSIGNED">\n'
	value += v3Indent(i+2) + '<id root="1.2.826.0.1285.0.1.10" extension="M85008"/>\n'
	value += v3Indent(i+2) + '<assignedOrganizationSDS classCode="ORG" determinerCode="INSTANCE">\n'
	value += v3Indent(i+3) + '<name>' + esc(Hospital) + '</name>\n'
	value += v3Indent(i+2) + '</assignedOrganizationSDS>\n'
	value += v3Indent(i+1) + '</assignedOrgSDS>\n'
	value += v3Indent(i)   + '</primaryInformationRecipient>\n'
	return value

This template calls a helper function, v3Indent(), which handles the details of generating the message output in the expected XML format with the proper indenting. For the sample message used in this tutorial, the output from v3HospitalReceiver() looks like this:

<primaryInformationRecipient typeCode="PRCP">
	<assignedOrgSDS classCode="ASSIGNED">
		<id root="1.2.826.0.1285.0.1.10" extension="M85008"/>
		<assignedOrganizationSDS classCode="ORG" determinerCode="INSTANCE">
			<name>The Requesting Organization</name>
		</assignedOrganizationSDS>
	</assignedOrgSDS>
</primaryInformationRecipient>

All of the other templates work the same way: they generate one specific section of a HL7 version 3 message, using the supplied parameters to customize this message section.

To view the HL7 V3 Python module, and the supporting module that contains the helper functions that the Python module uses, follow these links:

• hl7version3.py
• v3Helpers.py

	It is important to note that this Python module is not a HL7 version 3 message generation engine. It can only produce one specific type of HL7 version 3 message. However, you can use this technique to generate other HL7 version 3 messages. To do this: Determine the format of the HL7 version 3 message that you want to generate. Determine what data you need from your incoming HL7 2.x messages. Modify the VMD file described in Creating a VMD File To Extract Information in XML to extract this data and generate an XML file containing the data. Modify the hl7version3 Python module to generate the necessary templates for this message. Update the VMD file described in Creating a VMD File To Generate HL7 Version 3 Messages to use the modified Python module, supplying the data from the XML file.