From 6d01356ec667116a11ef912337a569c5abd2edf9 Mon Sep 17 00:00:00 2001
From: Matt Westcott <matt@west.co.tt>
Date: Mon, 10 Mar 2025 20:55:50 +0000
Subject: [PATCH] Rework deferring validation on StreamField
Overwriting a block's `required` option is not safe, as a block object is part of a class-level definition and is thus shared by all block instances, not just the one currently being validated. Instead, introduce a flag to Block.clean to skip 'required' validation.
---
wagtail/blocks/base.py | 20 ++++++++++++++++----
wagtail/blocks/stream_block.py | 4 ++--
2 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/wagtail/blocks/base.py b/wagtail/blocks/base.py
index 5c4ce2f2c3..cd73c8098e 100644
--- a/wagtail/blocks/base.py
+++ b/wagtail/blocks/base.py
@@ -756,10 +756,22 @@ class BlockField(forms.Field):
super().__init__(**kwargs)
def clean(self, value):
- # Pass required flag to the top-level block, so that dynamically setting it on the
- # field (e.g. by defer_required_fields) is respected by the block.
- self.block.set_meta_options({"required": self.required})
- return self.block.clean(value)
+ from wagtail.blocks.stream_block import StreamBlock
+
+ if isinstance(self.block, StreamBlock):
+ # StreamBlock is the only block type that is formally-supported as the top level block
+ # of a BlockField, but it's possible that other block types could be used, so check
+ # this explicitly.
+ # self.block has a `required` attribute that is consistent with the StreamField's `blank`
+ # attribute and thus the `required` attribute of BlockField - but if the latter has been
+ # assigned dynamically (e.g. by defer_required_fields) we want this to take precedence.
+ # We do this through the `ignore_required_constraints` flag recognised by
+ # StreamBlock.clean.
+ return self.block.clean(
+ value, ignore_required_constraints=not self.required
+ )
+ else:
+ return self.block.clean(value)
def has_changed(self, initial_value, data_value):
return self.block.get_prep_value(initial_value) != self.block.get_prep_value(
diff --git a/wagtail/blocks/stream_block.py b/wagtail/blocks/stream_block.py
index 95991ff28a..343754b76d 100644
--- a/wagtail/blocks/stream_block.py
+++ b/wagtail/blocks/stream_block.py
@@ -160,7 +160,7 @@ class BaseStreamBlock(Block):
def required(self):
return self.meta.required
- def clean(self, value):
+ def clean(self, value, ignore_required_constraints=False):
cleaned_data = []
errors = {}
non_block_errors = ErrorList()
@@ -179,7 +179,7 @@ class BaseStreamBlock(Block):
% {"min_num": self.meta.min_num}
)
)
- elif self.required and len(value) == 0:
+ elif self.required and not ignore_required_constraints and len(value) == 0:
non_block_errors.append(ValidationError(_("This field is required.")))
if self.meta.max_num is not None and self.meta.max_num < len(value):