Snapshot generation fails for Task resources

[wetret]

Snapshot generation fails if a task profile has more defined input slices than the highmed-task-base profile and throws the following exception:

org.hl7.fhir.exceptions.DefinitionException: Differential does not have a slice: 
Task.input/ (b:44 of 55 / 1/ 11) in profile 

[wetret]

Forge does not add slicing tags in slices of profiles if the parent profile already has the slicing information. The HAPI snapshot generator expect these slicing tags in every profile with slices, independent of the parent profile.

TODO: check FHIR spec if slicing information is needed multiple times or only when first slicing an element and not in the child profiles. Depending on this create bug report for HAPI or Forge.

Thanks @hhund for finding the issue!

[hhund]

Here's a patch that should fix issues with highmed-task-base-0.1.0.xml and highmed-task-request-simple-feasibility-0.1.0.xml I'm not sure tho if all my min max additions are necessary. The important bits are the tags for task.input and task.output

diff --git a/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-base-0.1.0.xml b/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-base-0.1.0.xml
index 75c3164..20286d0 100644
--- a/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-base-0.1.0.xml
+++ b/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-base-0.1.0.xml
@@ -52,7 +52,7 @@
           <type value="value" />
           <path value="type.coding.code" />
         </discriminator>
-        <rules value="openAtEnd" />
+        <rules value="open" />
       </slicing>
       <min value="3" />
     </element>
@@ -145,6 +145,11 @@
       <path value="Task.output" />
       <sliceName value="error" />
     </element>
+    <element id="Task.output:error.type.coding">
+      <path value="Task.output.type.coding" />
+      <min value="1" />
+      <max value="1" />
+    </element>
     <element id="Task.output:error.type.coding.system">
       <path value="Task.output.type.coding.system" />
       <fixedUri value="http://highmed.org/fhir/CodeSystem/bpmn-message" />
diff --git a/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-request-simple-feasibility-0.1.0.xml b/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-request-simple-feasibility-0.1.0.xml
index acd02ba..6007b4d 100644
--- a/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-request-simple-feasibility-0.1.0.xml
+++ b/dsf-fhir/dsf-fhir-server/src/main/resources/fhir/StructureDefinition/highmed-task-request-simple-feasibility-0.1.0.xml
@@ -18,7 +18,15 @@
     </element>
     <element id="Task.input">
       <path value="Task.input" />
+      <slicing>
+        <discriminator>
+          <type value="value" />
+          <path value="type.coding.code" />
+        </discriminator>
+        <rules value="closed" />
+      </slicing>
       <min value="4" />
+      <max value="4" />
     </element>
     <element id="Task.input:message-name">
       <path value="Task.input" />
@@ -34,6 +42,11 @@
       <min value="1" />
       <max value="1" />
     </element>
+    <element id="Task.input:research-study.type.coding">
+      <path value="Task.input.type.coding" />
+      <min value="1" />
+      <max value="1" />
+    </element>
     <element id="Task.input:research-study.type.coding.system">
       <path value="Task.input.type.coding.system" />
       <fixedUri value="http://highmed.org/fhir/CodeSystem/task-input" />
@@ -49,9 +62,27 @@
         <targetProfile value="http://highmed.org/fhir/StructureDefinition/highmed-research-study" />
       </type>
     </element>
+    <element id="Task.output">
+      <path value="Task.output" />
+      <slicing>
+        <discriminator>
+          <type value="value" />
+          <path value="type.coding.code" />
+        </discriminator>
+        <rules value="open" />
+      </slicing>
+      <min value="2" />
+    </element>
     <element id="Task.output:participatingMedics">
       <path value="Task.output" />
       <sliceName value="participatingMedics" />
+      <min value="1" />
+      <max value="1" />
+    </element>
+    <element id="Task.output:participatingMedics.type.coding">
+      <path value="Task.output.type.coding" />
+      <min value="1" />
+      <max value="1" />
     </element>
     <element id="Task.output:participatingMedics.type.coding.system">
       <path value="Task.output.type.coding.system" />
@@ -70,6 +101,13 @@
     <element id="Task.output:cohortSize">
       <path value="Task.output" />
       <sliceName value="cohortSize" />
+      <min value="1" />
+      <max value="1" />
+    </element>
+    <element id="Task.output:cohortSize.type.coding">
+      <path value="Task.output.type.coding" />
+      <min value="1" />
+      <max value="1" />
     </element>
     <element id="Task.output:cohortSize.type.coding.system">
       <path value="Task.output.type.coding.system" />

[hhund]

I not sure yet but the proposed fix e9e0fff for #43 might be a workaround for #45

[wetret]

According to the FHIR specification a re-slice of an already sliced element in the parent profile needs to define the tag again in the element to be sliced. See https://www.hl7.org/fhir/profiling-examples.html, section 5.1.1.7. This means that Forge probably has an error in creating slices in child profiles since the information is missing.