support __pydantic_extra__ when serializing (#576)

Author: samuelcolvin

pydantic_core/core_schema.py

@@ -30,7 +30,7 @@ class CoreConfig(TypedDict, total=False):
     config_choose_priority: int
     # if configs are merged, which should take precedence, default 0, default means child takes precedence
     config_merge_priority: int
-    # settings related to typed_dicts only
+    # settings related to typed dicts, model fields, dataclass fields
     extra_fields_behavior: ExtraBehavior
     typed_dict_total: bool  # default: True
     # used on typed-dicts and tagged union keys
@@ -2841,6 +2841,7 @@ class ModelSchema(TypedDict, total=False):
     revalidate_instances: Literal['always', 'never', 'subclass-instances']  # default: 'never'
     strict: bool
     frozen: bool
+    extra_behavior: ExtraBehavior
     config: CoreConfig
     ref: str
     metadata: Any
@@ -2855,6 +2856,7 @@ def model_schema(
     revalidate_instances: Literal['always', 'never', 'subclass-instances'] | None = None,
     strict: bool | None = None,
     frozen: bool | None = None,
+    extra_behavior: ExtraBehavior | None = None,
     config: CoreConfig | None = None,
     ref: str | None = None,
     metadata: Any = None,
@@ -2894,6 +2896,7 @@ class MyModel:
           should re-validate defaults to config.revalidate_instances, else 'never'
         strict: Whether the model is strict
         frozen: Whether the model is frozen
+        extra_behavior: The extra behavior to use for the model, used in serialization
         config: The config to use for the model
         ref: optional unique identifier of the schema, used to reference the schema in other places
         metadata: Any other information you want to include with the schema, not used by pydantic-core
@@ -2907,6 +2910,7 @@ class MyModel:
         revalidate_instances=revalidate_instances,
         strict=strict,
         frozen=frozen,
+        extra_behavior=extra_behavior,
         config=config,
         ref=ref,
         metadata=metadata,

src/build_tools.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::cmp::Ordering;
 use std::error::Error;
 use std::fmt;
 
@@ -280,3 +281,43 @@ impl ExtraBehavior {
         Ok(res)
     }
 }
+
+pub(crate) fn build_model_config<'a>(
+    py: Python<'a>,
+    schema: &'a PyDict,
+    parent_config: Option<&'a PyDict>,
+) -> PyResult<Option<&'a PyDict>> {
+    let child_config: Option<&PyDict> = schema.get_as(intern!(py, "config"))?;
+    match (parent_config, child_config) {
+        (Some(parent), None) => Ok(Some(parent)),
+        (None, Some(child)) => Ok(Some(child)),
+        (None, None) => Ok(None),
+        (Some(parent), Some(child)) => {
+            let key = intern!(py, "config_choose_priority");
+            let parent_choose: i32 = parent.get_as(key)?.unwrap_or_default();
+            let child_choose: i32 = child.get_as(key)?.unwrap_or_default();
+            match parent_choose.cmp(&child_choose) {
+                Ordering::Greater => Ok(Some(parent)),
+                Ordering::Less => Ok(Some(child)),
+                Ordering::Equal => {
+                    let key = intern!(py, "config_merge_priority");
+                    let parent_merge: i32 = parent.get_as(key)?.unwrap_or_default();
+                    let child_merge: i32 = child.get_as(key)?.unwrap_or_default();
+                    match parent_merge.cmp(&child_merge) {
+                        Ordering::Greater => {
+                            let new_child = child.copy()?;
+                            new_child.update(parent.as_mapping())?;
+                            Ok(Some(new_child))
+                        }
+                        // otherwise child is the winner
+                        _ => {
+                            let new_parent = parent.copy()?;
+                            new_parent.update(child.as_mapping())?;
+                            Ok(Some(new_parent))
+                        }
+                    }
+                }
+            }
+        }
+    }
+}