Errata backend

requirements.txt

@@ -59,6 +59,7 @@ python-magic==0.4.27
 pytz==2024.1
 requests==2.32.4
 six==1.16.0
+django-sortedm2m~=3.1
 sqlparse==0.4.4
 swapper==1.3.0
 tqdm==4.66.3

src/identifiers/logic.py

@@ -425,6 +425,7 @@ def create_crossref_article_context(article, identifier=None):
         "other_pages": article.page_numbers,
         "scheduled": article.scheduled_for_publication,
         "object": article,
+        "erratum_of": article.erratum_of(),
     }
 
     # append citations for i4oc compatibility

src/identifiers/tests/test_logic.py

@@ -241,6 +241,7 @@ def test_create_crossref_article_context_published(self):
             "date_accepted": None,
             "date_published": self.article_published.date_published,
             "doi": f"10.0000/TST.{self.article_published.id}",
+            "erratum_of": None,
             "id": self.article_published.id,
             "license": "",
             "object": self.article_published,
@@ -267,6 +268,7 @@ def test_create_crossref_article_context_not_published(self):
             "date_accepted": None,
             "date_published": None,
             "doi": self.doi_one.identifier,
+            "erratum_of": None,
             "id": self.article_one.id,
             "license": submission_models.Licence.objects.filter(
                 journal=self.journal_one,

src/submission/admin.py

@@ -260,6 +260,21 @@ def _answer(self, obj):
         return truncatewords_html(obj.answer, 10) if obj else ""
 
 
+class GenealogyAdmin(admin.ModelAdmin):
+    list_display = ("pk", "parent_id", "_parent_title")
+    list_filter = ("parent__journal",)
+    search_fields = (
+        "parent__pk",
+        "parent__title",
+        "children__pk",
+        "children__title",
+    )
+    raw_id_fields = ("parent", "children")
+
+    def _parent_title(self, obj):
+        return truncatewords_html(obj.parent.title, 10)
+
+
 class SubmissionConfigAdmin(admin.ModelAdmin):
     list_display = (
         "pk",
@@ -295,6 +310,7 @@ class SubmissionConfigAdmin(admin.ModelAdmin):
     (models.Keyword, KeywordAdmin),
     (models.SubmissionConfiguration, SubmissionConfigAdmin),
     (models.CreditRecord, CreditRecordAdmin),
+    (models.Genealogy, GenealogyAdmin),
 ]
 
 [admin.site.register(*t) for t in admin_list]

src/submission/migrations/0090_genealogy.py

@@ -0,0 +1,46 @@
+# Generated by Django 4.2.29 on 2026-04-27 11:51
+
+from django.db import migrations, models
+import django.db.models.deletion
+import sortedm2m.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("submission", "0089_merge_20260226_1524"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Genealogy",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                (
+                    "children",
+                    sortedm2m.fields.SortedManyToManyField(
+                        help_text=None,
+                        related_name="ancestors",
+                        to="submission.article",
+                    ),
+                ),
+                (
+                    "parent",
+                    models.OneToOneField(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="genealogy",
+                        to="submission.article",
+                        verbose_name="Original or main paper",
+                    ),
+                ),
+            ],
+        ),
+    ]

src/submission/models.py

@@ -64,6 +64,7 @@
 from utils.orcid import validate_orcid, COMPILED_ORCID_REGEX
 from utils.forms import plain_text_validator
 from journal import models as journal_models
+from sortedm2m.fields import SortedManyToManyField
 from review.const import (
     ReviewerDecisions as RD,
 )
@@ -2630,6 +2631,26 @@ def best_large_image_alt_text(self):
             )
         return default_text
 
+    def erratum_of(self):
+        """
+        Return the "parent" article for which this article is an erratum.
+
+        This is intended to be used in
+        templates/common/identifiers/crossref_article.xml
+        """
+        if self.section.name != "Erratum":
+            return None
+        if not self.ancestors.exists():
+            return None
+
+        # We can safely assume that an erratum refers to only one other paper
+        # so we just return the first "ancestor".
+        #
+        # Also, there is no need to check if the "parent" was published:
+        # the business logic should ensure that we cannot publish an erratum
+        # to a non-published paper.
+        return self.ancestors.first().parent
+
 
 class FrozenAuthorQueryset(model_utils.AffiliationCompatibleQueryset):
     AFFILIATION_RELATED_NAME = "frozen_author"
@@ -3400,6 +3421,28 @@ def handle_defaults(self, article):
         article.save()
 
 
+class Genealogy(models.Model):
+    """
+    Maintain relations of type parent/children between articles.
+
+    This can be used, for instance, to link erratum to the original paper.
+    """
+
+    parent = models.OneToOneField(
+        Article,
+        verbose_name=_("Original or main paper"),
+        on_delete=models.CASCADE,
+        related_name="genealogy",
+    )
+    children = SortedManyToManyField(
+        Article,
+        related_name="ancestors",
+    )
+
+    def __str__(self):
+        return f"Genealogy: {self.parent} has {self.children.count()} kids"
+
+
 # Signals
 
 

src/templates/common/identifiers/crossref_article.xml

@@ -54,6 +54,31 @@
                 <item_number item_number_type="article_number">{{ article.object.pk }}</item_number>
             </publisher_item>
 
+            {% if article.erratum_of %}
+            <crossmark>
+              <crossmark_policy>{{ article.object.journal|setting:'crossref_prefix' }}/not-used</crossmark_policy>
+              <updates>
+                <update type="erratum" date="{{ now|date:"Y-m-d" }}">{{ article.erratum_of.get_doi }}</update>
+              </updates>
+              {% if article.object.funders.exists %}
+              <custom_metadata>
+                <fr:program name="fundref">
+                    {% for funder in article.object.funders.all %}
+                    <fr:assertion name="fundgroup">
+                        <fr:assertion name="funder_name">{{ funder.name }}</fr:assertion>
+                        {% if funder.fundref_id %}
+                        <fr:assertion name="funder_identifier">{{ funder.fundref_id }}</fr:assertion>
+                        {% endif %}
+                        {% if funder.funding_id %}
+                        <fr:assertion name="award_number">{{ funder.funding_id }}</fr:assertion>
+                        {% endif %}
+                    </fr:assertion>
+                    {% endfor %}
+                </fr:program>
+              </custom_metadata>
+              {% endif %}
+            </crossmark>
+            {% else %}
             {% if article.object.funders.exists %}
             <fr:program name="fundref">
                 {% for funder in article.object.funders.all %}
@@ -69,8 +94,7 @@
                 {% endfor %}
             </fr:program>
             {% endif %}
-
-
+            {% endif %}
 
             <doi_data>
                 <doi>{{ article.doi }}</doi>