Support sub-attribute selection for structured attributes in publish configuration

docs/reference/item.md

@@ -487,7 +487,7 @@ Introduced in v2.2, Doorstop can include extended attributes in published output
 
 Edit the document configuration file `.doorstop.yml` by hand to include the desired attributes.
 
-For example, to include the `invented-by` extended attribute key and value in the published output:
+For example, to include the `invented-by` extended attribute in the published output:
 
 ```yaml
 settings:
@@ -497,4 +497,70 @@ settings:
 attributes:
   publish:
     - invented-by
-```
+```
+
+For simple scalar attributes (strings, numbers), the value is rendered directly in the output table.
+
+For list attributes, the values are joined with `<br>` as separator:
+
+```yaml
+# Item attribute:
+verification-method:
+  - system test
+  - analysis
+
+# Rendered as:
+# | verification-method | system test<br>analysis |
+```
+
+### Publishing sub-attributes of structured attributes
+
+When an extended attribute contains a **list of dictionaries** (a structured attribute), you can select specific sub-attributes for publishing instead of rendering the raw object.
+
+Use the attribute name directly as key with a `fields` configuration:
+
+```yaml
+attributes:
+  publish:
+    - invented-by           # simple attribute – unchanged behavior
+    - spec-refs-from:       # structured attribute – select sub-attributes
+        fields:
+          - url: section    # {url_key: label_key} → renders as a hyperlink
+    - spec-refs-to:
+        fields:
+          - url: section
+```
+
+The `fields` list supports three entry formats:
+
+| Format                                      | Example        | Result                                 |
+| ------------------------------------------- | -------------- | -------------------------------------- |
+| `{url_key: label_key}`                      | `url: section` | single field as link text              |
+| `{url_key: {label: [...], separator: ...}}` | see below      | multiple fields combined as link text  |
+| `fieldname`                                 | `section`      | plain text value of that sub-attribute |
+
+**Simple label (single field):**
+```yaml
+attributes:
+  publish:
+    - spec-refs-from:
+        fields:
+          - url: section
+# → [Stop Functions](https://...)
+```
+
+**Combined label (multiple fields):**
+```yaml
+attributes:
+  publish:
+    - spec-refs-from:
+        fields:
+          - url:
+              label: [file, section]
+              separator: ": "
+# → [System_Safety_Concept: Stop Functions](https://...)
+```
+
+The `label` key accepts a list of sub-attribute names. The `separator` key is optional and defaults to `": "` if omitted.
+
+Multiple entries in the structured attribute list are separated by `<br>` in the published output.

doorstop/core/publishers/markdown.py

@@ -257,6 +257,69 @@ def _generate_heading_from_item(self, item, to_html=False):
             result = standard + attr_list
         return result
 
+    @staticmethod
+    def _parse_publish_entry(entry):
+        """Parse a publish entry from .doorstop.yml.
+
+        Backward compatible:
+        - str  → {'attr': entry, 'fields': None}
+        - dict with single key → {'attr': key, 'fields': config.get('fields')}
+        """
+        if isinstance(entry, str):
+            return {"attr": entry, "fields": None}
+        elif isinstance(entry, dict):
+            if len(entry) == 1:
+                attr = next(iter(entry))
+                config = entry[attr]
+                if isinstance(config, dict):
+                    return {"attr": attr, "fields": config.get("fields", None)}
+                else:
+                    return {"attr": attr, "fields": None}
+        return None
+
+    @staticmethod
+    def _render_fields(refs: list, fields: list) -> str:
+        results = []
+        for ref in refs:
+            parts = []
+            for field_entry in fields:
+                if isinstance(field_entry, dict):
+                    for url_key, label_spec in field_entry.items():
+                        url = ref.get(url_key, "").strip()
+
+                        # label_spec may be one of:
+                        # - str:  label: section          → single field
+                        # - dict: label: [file, section]  → combined label
+                        if isinstance(label_spec, str):
+                            # single field
+                            label = ref.get(label_spec, url_key).strip()
+                        elif isinstance(label_spec, dict):
+                            # combined label
+                            label_fields = label_spec.get("label", [])
+                            separator = label_spec.get("separator", ": ")
+                            if isinstance(label_fields, str):
+                                label_fields = [label_fields]
+                            label = separator.join(
+                                str(ref.get(f, "")).strip()
+                                for f in label_fields
+                                if ref.get(f, "").strip()
+                            )
+                            if not label:
+                                label = url_key
+                        else:
+                            label = url_key
+
+                        if url:
+                            parts.append(f"[{label}]({url})")
+                        else:
+                            parts.append(label)
+
+                elif isinstance(field_entry, str):
+                    parts.append(str(ref.get(field_entry, "")).strip())
+
+            results.append(" ".join(parts))
+        return "<br>".join(results)
+
     def _lines_markdown(self, obj, **kwargs):
         """Yield lines for a Markdown report.
 
@@ -269,7 +332,7 @@ def _lines_markdown(self, obj, **kwargs):
         linkify = kwargs.get("linkify", False)
         to_html = kwargs.get("to_html", False)
         for item in iter_items(obj):
-            # Create iten heading.
+            # Create item heading.
             complete_heading = self._generate_heading_from_item(item, to_html=to_html)
             yield complete_heading
 
@@ -313,17 +376,44 @@ def _lines_markdown(self, obj, **kwargs):
             # Add custom publish attributes
             if item.document and item.document.publish:
                 header_printed = False
-                for attr in item.document.publish:
-                    if not item.attribute(attr):
+                for entry in item.document.publish:
+                    parsed = self._parse_publish_entry(entry)
+                    attr = parsed.get("attr") if parsed else None
+                    fields = parsed.get("fields") if parsed else None
+                    if not attr:  # catches None AND missing 'attr'
                         continue
+
+                    value = item.attribute(attr)
+                    if not value:
+                        continue
+
                     if not header_printed:
                         header_printed = True
                         yield ""
                         yield "| Attribute | Value |"
                         yield "| --------- | ----- |"
-                    yield "| {} | {} |".format(attr, item.attribute(attr))
-                yield ""
 
+                    # Sub-Attribute-Selection: fields given and value is a list of dicts
+                    if (
+                        fields
+                        and isinstance(fields, list)
+                        and isinstance(value, list)
+                        and value
+                        and isinstance(value[0], dict)
+                    ):
+                        rendered = self._render_fields(value, fields)
+                        yield "| {} | {} |".format(attr, rendered)
+
+                    # Fallback: standard case (backward compatible)
+                    else:
+                        if isinstance(value, list):
+                            yield "| {} | {} |".format(
+                                attr, "<br>".join(str(v) for v in value)
+                            )
+                        else:
+                            yield "| {} | {} |".format(attr, value)
+                if header_printed:
+                    yield ""
             yield ""  # break between items
 
 

doorstop/core/publishers/tests/helpers.py

@@ -15,6 +15,7 @@
         - REQ002: # Hello, world! !["...
         - REQ2-001: # Hello, world!
 """
+
 YAML_CUSTOM_ATTRIBUTES = """
 settings:
   digits: 3
@@ -26,6 +27,65 @@
     - CUSTOM-ATTRIB
     - invented-by
 """
+
+YAML_STRUCTURED_ATTRIBUTES = """\
+settings:
+  digits: 3
+  prefix: REQ
+  sep: ''
+attributes:
+  publish:
+    - type
+    - verification-method
+    - spec-refs-from:
+        fields:
+          - url: section
+"""
+
+YAML_LIST_ATTRIBUTE = """\
+settings:
+  digits: 3
+  prefix: REQ
+  sep: ''
+attributes:
+  publish:
+    - verification-method
+"""
+
+YAML_INVALID_PUBLISH_ENTRY = """\
+settings:
+  digits: 3
+  prefix: REQ
+  sep: ''
+attributes:
+  publish:
+    - ~
+"""
+
+YAML_COMBINED_LABEL_ATTRIBUTES = """\
+settings:
+  digits: 3
+  prefix: REQ
+  sep: ''
+attributes:
+  publish:
+    - spec-refs-from:
+        fields:
+          - url:
+              label: [file, section]
+              separator: ": "
+"""
+
+YAML_SINGLE_ATTRIBUTE = """\
+settings:
+  digits: 3
+  prefix: REQ
+  sep: ''
+attributes:
+  publish:
+    - type
+"""
+
 HTML_TEMPLATE_WALK = """
     template/
         bootstrap.bundle.min.js