Feature: Conditional Resource Templates

[stueynz]

Sometimes, when dealing with custom HL7 segments the correct FHIR resource for the segment differs
depending upon some value in the segment. For example, in our ZAL custom Alert segment field ZAL.2.1 denotes the Alert Category, and when the value is one of A1, A3, H2 or H4 then the correct FHIR resource is AllergyIntolerance; for all other
alert category values the correct FHIR resource is Flag

Two resources template entries with suitable condition expressions will direct each ZAL segment to its correct resource template.

resources:
    - resourceName: AllergyIntolerance
      segment: ZAL
      resourcePath: resource/AllergyIntoleranceZAL
      repeats: true
      condition: ZAL.2.1 IN [A1, A3, H2, H4]          ## Some of our custom ZAL segments are AllergyIntolerance
      additionalSegments:

    - resourceName: Flag
      segment: ZAL
      resourcePath: resource/FlagZAL
      repeats: true
      condition: ZAL.2.1 NOT_IN [A1, A3, H2, H4]      ## The rest of our custom ZAL segments are more general alert Flags
      additionalSegments:

The grammar for the condition field is as follows:

   <hl7spec>  EQUALS | NOT_EQUALS | IN | NOT_IN | NULL | NOT_NULL   <value> | [ ... ]

Notes:

• hl7spec uses the same dot notation as expression syntax inside templates and can be of the folowing forms:

  • SEGMENT
  • SEGMENT.FIELD
  • SEGMENT.FIELD.COMPONENT
  • SEGMENT.FIELD.COMPONENT.SUBCOMPONENT
  • SEGMENT.FIELD(REPETITION)
  • SEGMENT.FIELD(REPETITION).COMPONENT
  • SEGMENT.FIELD(REPETITION).COMPONENT.SUBCOMPONENT

  ZAL, ZAL.2, ZAL.2.1, ZAL.2.1.2, PID.14(1).2 & PID.14(1).2.1 are all valid values for hl7spec.

• The SEGMENT part of hl7spec MUST match the value of the segment field.

• EQUALS and NOT_EQUALS expressions only accept a single value on the right-hand side of the expression.

• IN and NOT_IN expressions only accept a list of values, delimited by comma, in square brackets on the right-hand side of the expression.

• NULL and NOT_NULL do not accept any value.

• The condition expression cannot be much more complex, as there are no context variables available at evaluation time.

Examples:

• PID.5.1.2 EQUALS van
• ZAL.2.1.3 NOT_NULL
• ZAL.2(1).1 NULL
• ZAL.3.1 IN [A3, A4, H1, H3, FA, DA]
• ZAL.3.1 NOT_IN [A2, F3, DA]
• ZAL.2 EQUALS A4
• ZAL NOT_EQUALS H2

[stueynz]

Discussion on whether or not this is a GoodThing (tm) should probably take place in the matching #508 Issue.

[LisaWellman]

@stueynz thank you for your contribution, I have not reviewed but a quick glance it looks quite complete! Can you sign to handle the DCO?

[LisaWellman]

@stueynz I see no activity here; do you still want to pursue?