Clinical Data Export

ClinicalDataSerializer exports submitted CRF values as ODM <ClinicalData> XML.

The data is read directly from the SubjectVisit model and the CRF instances linked to each visit — a CRF instance existing for a subject_visit is the source of truth that it was entered. (There is no dependency on the CrfMetadata layer.)

Usage

from edc_cdisc.serializers import ClinicalDataSerializer

xml_bytes = ClinicalDataSerializer(
    edc_module_name="meta_edc",
    visit_schedule=visit_schedule,
    subject_identifiers=["100-0001"],   # optional, None = all subjects
    include_nulls=False,                # optional
).to_xml()

Output structure

ODM
  ClinicalData  (StudyOID="S.<protocol>" MetaDataVersionOID="MDV.<fp>")
    SubjectData  (SubjectKey="<subject_identifier>")
      StudyEventData  (StudyEventOID="SE.<code>" | "UE.<code>" | "CE.<model>")
        FormData  (FormOID="F.<model>")
          ItemGroupData  (ItemGroupOID="IG.<section>")
            ItemData  (ItemOID="I.<model>.<field>" Value="…")

ClinicalData references the metadata by OID (StudyOID and MetaDataVersionOID) rather than nesting it — so a data file links to the metadata edition it conforms to. The MetaDataVersionOID is the same MDV.<fingerprint> the metadata serializer stamps.

Study events

A subject’s SubjectVisit rows map to StudyEventData by visit code and sequence:

• visit_code_sequence == 0 → scheduled → StudyEventOID="SE.<code>".

• visit_code_sequence > 0 → unscheduled → StudyEventOID="UE.<code>" with StudyEventRepeatKey="<sequence>" (unscheduled events repeat).

• Death-report / offstudy singletons → StudyEventOID="CE.<model>".

A negative visit_code_sequence raises NegativeVisitCodeSequenceError — it indicates corrupt state, and the export refuses to run rather than emit a misleading file.

Null values

By default a null field is omitted, so each form instance contributes a variable number of ItemData rows. Pass include_nulls=True to emit <ItemData IsNull="Yes"/> for every null field instead — then every form instance carries a fixed number of items, which makes record counts easy to reconcile against the source tables. Note that an empty string is real (entered-but-blank) data and is always emitted as Value=""; only None is treated as null.