Preserve definition-level defaults when types are reached via $ref

typify-impl/src/lib.rs

@@ -706,6 +706,12 @@ impl TypeSpace {
 
     fn convert_ref_type(&mut self, type_name: Name, schema: Schema, type_id: TypeId) -> Result<()> {
         let (mut type_entry, metadata) = self.convert_schema(type_name.clone(), &schema)?;
+        // Note that the conversion may have already recorded a default drawn
+        // from the definition's own metadata (e.g. structs record it in
+        // TypeEntryStruct::from_metadata and return no metadata). Only
+        // override that value if the metadata returned by the conversion
+        // actually specifies a default--such as one declared at the reference
+        // site--rather than clobbering it with `None`.
         let default = metadata
             .as_ref()
             .and_then(|m| m.default.as_ref())
@@ -714,15 +720,21 @@ impl TypeSpace {
         let type_entry = match &mut type_entry.details {
             // The types that are already named are good to go.
             TypeEntryDetails::Enum(details) => {
-                details.default = default;
+                if default.is_some() {
+                    details.default = default;
+                }
                 type_entry
             }
             TypeEntryDetails::Struct(details) => {
-                details.default = default;
+                if default.is_some() {
+                    details.default = default;
+                }
                 type_entry
             }
             TypeEntryDetails::Newtype(details) => {
-                details.default = default;
+                if default.is_some() {
+                    details.default = default;
+                }
                 type_entry
             }
 

typify/tests/schemas/ref-with-default.json

@@ -0,0 +1,48 @@
+{
+  "$comment": "definition-level defaults should survive $ref resolution",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "DefaultedStruct": {
+      "type": "object",
+      "properties": {
+        "a": {
+          "type": "string"
+        }
+      },
+      "additionalProperties": false,
+      "default": {
+        "a": "hello"
+      }
+    },
+    "DefaultedEnum": {
+      "type": "string",
+      "enum": [
+        "alpha",
+        "beta",
+        "gamma"
+      ],
+      "default": "beta"
+    },
+    "Root": {
+      "type": "object",
+      "properties": {
+        "via_ref": {
+          "$ref": "#/definitions/DefaultedStruct"
+        },
+        "enum_via_ref": {
+          "$ref": "#/definitions/DefaultedEnum"
+        },
+        "override_at_ref": {
+          "default": {
+            "a": "override"
+          },
+          "allOf": [
+            {
+              "$ref": "#/definitions/DefaultedStruct"
+            }
+          ]
+        }
+      }
+    }
+  }
+}