Add support for Collaborator field to be upserted (baserow#4558)

* Ensure that a string ID is handled when upserting a collaborator field.

* Update changelog

* Fix serializer check

* Create a new CollaboratorField that supports both int, dicts, and string numbers.

* Add tests for CollaboratorField

* Set required=False as a default

* Fix domain for changelog

* Add database changelog

Author: paljort

backend/src/baserow/contrib/database/api/fields/serializers.py

@@ -447,11 +447,40 @@ class UniqueRowValuesSerializer(serializers.Serializer):
     values = serializers.ListSerializer(child=serializers.CharField())
 
 
+@extend_schema_field(OpenApiTypes.INT)
+class CollaboratorField(serializers.Field):
+    """
+    A serializer field that accepts an int or a dict with an "id" field.
+    """
+
+    def to_internal_value(self, data):
+        if isinstance(data, int) or (isinstance(data, str) and data.isdigit()):
+            return int(data)
+
+        if isinstance(data, dict):
+            try:
+                return int(data["id"])
+            except (KeyError, TypeError, ValueError):
+                pass
+
+        raise serializers.ValidationError(
+            "Expected an integer or an object with an 'id' field",
+            code="invalid",
+        )
+
+    def to_representation(self, value):
+        return value
+
+
 class CollaboratorSerializer(serializers.Serializer):
     id = serializers.IntegerField()
     name = serializers.CharField(source="first_name", read_only=True)
 
 
+class CollaboratorRequestSerializer(serializers.ListSerializer):
+    child = CollaboratorField()
+
+
 class AvailableCollaboratorsSerializer(serializers.ListField):
     def __init__(self, **kwargs):
         kwargs["child"] = CollaboratorSerializer()

backend/src/baserow/contrib/database/fields/field_types.py

@@ -6744,18 +6744,13 @@ def can_represent_collaborators(self, field):
         return True
 
     def get_serializer_field(self, instance, **kwargs):
-        required = kwargs.pop("required", False)
-        field_serializer = CollaboratorSerializer(
-            **{
-                "required": required,
-                "allow_null": False,
-                **kwargs,
-            }
-        )
-        return serializers.ListSerializer(
-            child=field_serializer, required=required, **kwargs
+        from baserow.contrib.database.api.fields.serializers import (
+            CollaboratorRequestSerializer,
         )
 
+        kwargs.setdefault("required", False)
+        return CollaboratorRequestSerializer(**kwargs)
+
     def get_search_expression(
         self, field: MultipleCollaboratorsField, queryset: QuerySet
     ) -> Expression:

backend/tests/baserow/contrib/database/api/fields/test_collaborator_serializers.py

@@ -0,0 +1,54 @@
+import pytest
+from rest_framework import serializers
+
+from baserow.contrib.database.api.fields.serializers import (
+    CollaboratorField,
+    CollaboratorRequestSerializer,
+)
+
+
+def test_collaborator_request_serializer_with_list_of_ints():
+    result = CollaboratorRequestSerializer().to_internal_value([1, 2, 3])
+    assert result == [1, 2, 3]
+
+
+def test_collaborator_request_serializer_with_list_of_dicts():
+    result = CollaboratorRequestSerializer().to_internal_value([{"id": 1}, {"id": 2}])
+    assert result == [1, 2]
+
+
+def test_collaborator_request_serializer_with_ints_and_dicts():
+    serializer = CollaboratorRequestSerializer()
+    result = serializer.to_internal_value([1, {"id": 2}, "3"])
+    assert result == [1, 2, 3]
+
+
+def test_collaborator_field_int():
+    assert CollaboratorField().to_internal_value(100) == 100
+
+
+def test_collaborator_field_numeric_string():
+    assert CollaboratorField().to_internal_value("200") == 200
+
+
+def test_collaborator_field_dict_with_int_id():
+    assert CollaboratorField().to_internal_value({"id": 300}) == 300
+
+
+def test_collaborator_field_dict_with_string_id():
+    assert CollaboratorField().to_internal_value({"id": "404"}) == 404
+
+
+def test_collaborator_field_dict_without_id():
+    with pytest.raises(serializers.ValidationError):
+        CollaboratorField().to_internal_value({"foo": "bar"})
+
+
+def test_collaborator_field_invalid_type():
+    with pytest.raises(serializers.ValidationError):
+        CollaboratorField().to_internal_value(["foo"])
+
+
+def test_collaborator_field_non_numeric_string():
+    with pytest.raises(serializers.ValidationError):
+        CollaboratorField().to_internal_value("foo bar")

backend/tests/baserow/contrib/database/field/test_multiple_collaborators_field_type.py

@@ -50,6 +50,29 @@ def test_multiple_collaborators_field_type_create(data_fixture):
     assert collaborator_field_list[0].id == user.id
 
 
+@pytest.mark.django_db
+@pytest.mark.field_multiple_collaborators
+def test_multiple_collaborators_field_type_create_with_int(data_fixture):
+    user = data_fixture.create_user()
+    database = data_fixture.create_database_application(user=user, name="Placeholder")
+    table = data_fixture.create_database_table(name="Example", database=database)
+
+    row_handler = RowHandler()
+
+    collaborator_field = data_fixture.create_multiple_collaborators_field(
+        user=user, table=table, name="Collaborator 1"
+    )
+    field_id = collaborator_field.db_column
+
+    assert MultipleCollaboratorsField.objects.all().first().id == collaborator_field.id
+
+    row = row_handler.create_row(user=user, table=table, values={field_id: [user.id]})
+    assert row.id
+    collaborator_field_list = getattr(row, field_id).all()
+    assert len(collaborator_field_list) == 1
+    assert collaborator_field_list[0].id == user.id
+
+
 @pytest.mark.django_db
 @pytest.mark.field_multiple_collaborators
 def test_multiple_collaborators_field_type_update(data_fixture):

backend/tests/baserow/contrib/integrations/local_baserow/service_types/test_upsert_row_service_type.py

@@ -833,3 +833,43 @@ def test_extract_properties_returns_expected_list(path, expected):
     result = service_type.extract_properties(path)
 
     assert result == expected
+
+
+@pytest.mark.django_db
+def test_local_baserow_upsert_row_service_dispatch_data_with_collaborators(
+    data_fixture,
+):
+    user = data_fixture.create_user()
+    page = data_fixture.create_builder_page(user=user)
+    integration = data_fixture.create_local_baserow_integration(
+        application=page.builder, user=user
+    )
+    database = data_fixture.create_database_application(
+        workspace=page.builder.workspace
+    )
+    table = TableHandler().create_table_and_fields(
+        user=user,
+        database=database,
+        name=data_fixture.fake.name(),
+        fields=[
+            ("Collaborators", "multiple_collaborators", {}),
+        ],
+    )
+    collaborator_field = table.field_set.get(name="Collaborators")
+
+    service = data_fixture.create_local_baserow_upsert_row_service(
+        integration=integration,
+        table=table,
+    )
+    service_type = service.get_type()
+    # Simulate a user ID as a string
+    service.field_mappings.create(field=collaborator_field, value=f'"{user.id}"')
+
+    dispatch_context = FakeDispatchContext()
+    dispatch_values = service_type.resolve_service_formulas(service, dispatch_context)
+    dispatch_data = service_type.dispatch_data(
+        service, dispatch_values, dispatch_context
+    )
+
+    collaborators = getattr(dispatch_data["data"], collaborator_field.db_column).all()
+    assert list(collaborators.values_list("id", flat=True)) == [user.id]

changelog/entries/unreleased/bug/3954_fixed_a_bug_preventing_collaborator_field_from_being_upserte.json

@@ -0,0 +1,9 @@
+{
+    "type": "bug",
+    "message": "Fixed a bug preventing Collaborator field from being upserted by user ID.",
+    "issue_origin": "github",
+    "issue_number": 3954,
+    "domain": "database",
+    "bullet_points": [],
+    "created_at": "2026-01-28"
+}

changelog/entries/unreleased/bug/3954_fixed_a_bug_where_the_collaborators_field_couldnt_be_updated.json

@@ -0,0 +1,9 @@
+{
+    "type": "bug",
+    "message": "Fixed a bug where the collaborators field couldn't be updated via upsert actions.",
+    "issue_origin": "github",
+    "issue_number": 3954,
+    "domain": "integration",
+    "bullet_points": [],
+    "created_at": "2026-01-19"
+}