FlexFieldsWriteableNestedSerializerMixin
Overview
This is a utility mixin making a single class that makes serializers flex & nested writable.
apply_flex_fields
Apply sparse-fieldset and expansion options to fields in place.
Removes fields that are excluded by omit or not present in fields (sparse-fieldset), then replaces fields listed in expand with their nested serializer instances. Returns the modified fields mapping.
Signature
apply_flex_fields(self, fields, flex_options)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| fields | yes | |||
| flex_options | yes |
Source
server/vueda/core/serializers/__init__.py:221
save
Roll back the whole nested write if any related mutation is denied or invalid.
Signature
save(self, kwargs)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| kwargs | no |
Source
server/vueda/core/serializers/__init__.py:216
to_internal_value
?e= (expand) names relations whose payload is a nested object rather than a flat PK, so each expanded relation is swapped for its nested serializer here, before deserialization, to accept that shape. See the nested-writable-inlines guide for the query-param contract; this half of flex-field handling is independent of sparse-fieldset narrowing and stays on the write path.
?f=/?om= are not applied here. They narrow the representation only, in to_representation (via ensure_flex_fields_applied), so a required field they exclude still fails validation instead of silently losing its validator. Deserialization must not call ensure_flex_fields_applied for this reason: that helper runs the full apply_flex_fields, sparse-fieldset removal included, which is exactly what would drop the validator.
Signature
to_internal_value(self, data)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| data | yes |
Source
server/vueda/core/serializers/__init__.py:266
to_representation
?f=/?om= (_flex_options_rep_only, sourced from query params) narrow the representation only. Applying them here, rather than in to_internal_value, keeps a write validating against the serializer's full field set while still narrowing the response a write returns, since to_representation runs after save().
fields=/omit= passed as serializer kwargs (_flex_options_base) are a different entry point: get_fields() applies them before either to_internal_value or to_representation runs, so they narrow validation and representation alike. That is unchanged and deliberate -- a caller constructing a serializer with explicit kwargs is opting in to restricting both directions, unlike a client shaping a response with a query parameter.
Delegates the view-bound check and the actual application to ensure_flex_fields_applied, the same helper a caller like VuedaViewSet.get_queryset uses to resolve .fields before an instance is ever serialized (for prefetch planning). Both call sites must agree on when application is safe and on the _flex_fields_rep_applied double-application guard, so that logic lives in one place rather than two copies that could drift.
Signature
to_representation(self, instance)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| instance | yes |
Source
server/vueda/core/serializers/__init__.py:241
update
Signature
update(self, instance, validated_data)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| instance | yes | |||
| validated_data | yes |
Source
server/vueda/core/serializers/__init__.py:512
update_or_create_direct_relations
Save each direct relation's row after checking the related viewset's permissions.
An entry that holds only a primary key links the existing row without saving it or checking permissions, when the field has no save arguments. With save arguments, the serializer checks and saves the row like any other entry. An unknown primary key raises a validation error under the field name.
Signature
update_or_create_direct_relations(self, attrs, relations)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| attrs | yes | |||
| relations | yes |
Source
server/vueda/core/serializers/__init__.py:414
update_or_create_reverse_relations
Save each reverse relation's rows, matching submitted pks only against the parent's rows.
drf-writable-nested looks up submitted child pks across the whole child table, then saves each match with its foreign key set to this parent. A pk that belongs to another parent's row would move that row here and update it, although the request was authorized only for this parent. Each relation is saved on its own, so the lookup can be limited to rows that already belong to this parent. A pk outside that set matches no row, and the library saves that entry as a new row, as it does for any unknown pk.
Many-to-many entries may link shared rows by pk. Changes to those rows require the related model's permissions, while parent-owned reverse children keep their matching rules.
Signature
update_or_create_reverse_relations(self, instance, reverse_relations)
Parameters
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
| self | yes | |||
| instance | yes | |||
| reverse_relations | yes |
Source
server/vueda/core/serializers/__init__.py:430
Source
server/vueda/core/serializers/__init__.py:206