Fix JSON schema generation for Dry::Struct wrapped in constructors

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Break Versioning](https://www.taoensso.com/break-ve
 
 ## [Unreleased]
 
+### Fixed
+
+- JSON schema generation now properly handles Dry::Struct wrapped in constructors (fixes #495) (@baweaver)
 
 ## [1.14.1] - 2025-03-03
 

lib/dry/schema/extensions/struct.rb

@@ -27,7 +27,8 @@ def call(*args)
                                    "a struct class (#{name.inspect} => #{args[0]})"
             end
 
-            schema = struct_compiler.(args[0])
+            struct_class = extract_struct_class(args[0])
+            schema = struct_compiler.(struct_class)
 
             super(schema, *args.drop(1))
             type(schema_dsl.types[name].constructor(schema))
@@ -39,7 +40,18 @@ def call(*args)
         private
 
         def struct?(type)
-          type.is_a?(::Class) && type <= ::Dry::Struct
+          (type.is_a?(::Class) && type <= ::Dry::Struct) ||
+            (type.is_a?(::Dry::Types::Constructor) && type.primitive <= ::Dry::Struct)
+        end
+
+        def extract_struct_class(type)
+          if type.is_a?(::Class) && type <= ::Dry::Struct
+            type
+          elsif type.is_a?(::Dry::Types::Constructor) && type.primitive <= ::Dry::Struct
+            type.primitive
+          else
+            type
+          end
         end
       })
     end

spec/integration/extensions/json_schema/struct_constructor_spec.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+require "dry-struct"
+require "dry/schema/extensions/struct"
+
+RSpec.describe "JSON Schema with struct constructors" do
+  before do
+    Dry::Schema.load_extensions(:json_schema)
+  end
+
+  let(:address_struct) do
+    Class.new(Dry::Struct) do
+      attribute :street, Types::Strict::String.optional.default(nil)
+      attribute :city, Types::Strict::String
+    end
+  end
+
+  context "with direct struct" do
+    let(:schema) do
+      struct = address_struct
+      Dry::Schema.Params do
+        required(:address).value(struct)
+      end
+    end
+
+    it "generates JSON schema with struct properties" do
+      json_schema = schema.json_schema
+
+      expect(json_schema[:properties][:address]).to include(
+        type: "object",
+        properties: {
+          street: { anyOf: [{ type: "null" }, { type: "string" }] },
+          city: { type: "string" }
+        },
+        required: ["street", "city"]
+      )
+    end
+  end
+
+  context "with struct constructor" do
+    let(:schema) do
+      struct = address_struct
+      Dry::Schema.Params do
+        required(:address).value(struct.constructor(&:itself))
+      end
+    end
+
+    it "generates JSON schema with struct properties" do
+      json_schema = schema.json_schema
+
+      expect(json_schema[:properties][:address]).to include(
+        type: "object",
+        properties: {
+          street: { anyOf: [{ type: "null" }, { type: "string" }] },
+          city: { type: "string" }
+        },
+        required: ["street", "city"]
+      )
+    end
+  end
+
+  context "comparing direct struct vs constructor" do
+    let(:direct_schema) do
+      struct = address_struct
+      Dry::Schema.Params do
+        required(:address).value(struct)
+      end
+    end
+
+    let(:constructor_schema) do
+      struct = address_struct
+      Dry::Schema.Params do
+        required(:address).value(struct.constructor(&:itself))
+      end
+    end
+
+    it "generates identical JSON schemas" do
+      expect(direct_schema.json_schema).to eq(constructor_schema.json_schema)
+    end
+  end
+end