Preserve default values for input object fields when extracting subgraph

gateway-js/CHANGELOG.md

@@ -4,6 +4,8 @@ This CHANGELOG pertains only to Apollo Federation packages in the 2.x range. The
 
 ## vNext
 
+- Preserve default values of input object fields [PR #2218](https://github.com/apollographql/federation/pull/2218).
+
 ## 2.1.4
 
 - Ensures supergraph `@defer`/`@stream` definitions of supergraph are not included in the API schema [PR #2212](https://github.com/apollographql/federation/pull/2212).

internals-js/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## vNext
 
+- Preserve default values of input object fields [PR #2218](https://github.com/apollographql/federation/pull/2218).
 
 ## 2.1.4
 

internals-js/src/__tests__/extractSubgraphsFromSupergraph.test.ts

@@ -1,4 +1,4 @@
-import { buildSupergraphSchema, extractSubgraphsFromSupergraph } from "..";
+import { buildSupergraphSchema, extractSubgraphsFromSupergraph, InputObjectType } from "..";
 
 
 test('handles types having no fields referenced by other objects in a subgraph correctly', () => {
@@ -534,6 +534,69 @@ test('handles unions types having no members in a subgraph correctly', () => {
   expect(a.type('D')).toBeDefined();
 })
 
+test('preserves default values of input object fields', () => {
+  const supergraph = `
+    schema
+      @link(url: "https://specs.apollo.dev/link/v1.0")
+      @link(url: "https://specs.apollo.dev/join/v0.2", for: EXECUTION)
+    {
+      query: Query
+    }
+
+    directive @join__field(graph: join__Graph!, requires: join__FieldSet, provides: join__FieldSet, type: String, external: Boolean, override: String, usedOverridden: Boolean) repeatable on FIELD_DEFINITION | INPUT_FIELD_DEFINITION
+
+    directive @join__graph(name: String!, url: String!) on ENUM_VALUE
+
+    directive @join__implements(graph: join__Graph!, interface: String!) repeatable on OBJECT | INTERFACE
+
+    directive @join__type(graph: join__Graph!, key: join__FieldSet, extension: Boolean! = false, resolvable: Boolean! = true) repeatable on OBJECT | INTERFACE | UNION | ENUM | INPUT_OBJECT | SCALAR
+
+    directive @link(url: String, as: String, for: link__Purpose, import: [link__Import]) repeatable on SCHEMA
+
+    input Input
+      @join__type(graph: SERVICE)
+    {
+      a: Int! = 1234
+    }
+
+    scalar join__FieldSet
+
+    enum join__Graph {
+      SERVICE @join__graph(name: "service", url: "")
+    }
+
+    scalar link__Import
+
+    enum link__Purpose {
+      """
+      \`SECURITY\` features provide metadata necessary to securely resolve fields.
+      """
+      SECURITY
+
+      """
+      \`EXECUTION\` features provide metadata necessary for operation execution.
+      """
+      EXECUTION
+    }
+
+    type Query
+      @join__type(graph: SERVICE)
+    {
+      field(input: Input!): String
+    }
+  `;
+
+  const schema = buildSupergraphSchema(supergraph)[0];
+  const subgraphs = extractSubgraphsFromSupergraph(schema);
+
+  const subgraph = subgraphs.get('service')
+  const inputType = subgraph?.schema.type('Input') as InputObjectType | undefined
+  const inputFieldA = inputType?.field('a')
+
+  expect(inputFieldA?.defaultValue).toBe(1234)
+})
+
+
 test('throw meaningful error for invalid federation directive fieldSet', () => {
   const supergraph = `
     schema

internals-js/src/extractSubgraphsFromSupergraph.ts

@@ -595,7 +595,9 @@ function addSubgraphInputField(
     const copiedType = encodedType
       ? decodeType(encodedType, subgraph.schema, subgraph.name)
       : copyType(supergraphField.type!, subgraph.schema, subgraph.name);
-    return (subgraphType as InputObjectType).addField(supergraphField.name, copiedType);
+    const field = (subgraphType as InputObjectType).addField(supergraphField.name, copiedType);
+    field.defaultValue = supergraphField.defaultValue
+    return field
   } else {
     return undefined;
   }