fix: remove legacy features preventing federating 2 PostGraphiles

__tests__/__snapshots__/integration.test.ts.snap

@@ -58,23 +58,6 @@ interface Node {
 }
 
 type Query {
-  """
-  Exposes the root query type nested one level down. This is helpful for Relay 1
-  which can only query top level fields if they are in a particular form.
-  """
-  query: Query!
-
-  """
-  The root query type must be a \`Node\` to work well with Relay 1 mutations. This just resolves to \`query\`.
-  """
-  nodeId: ID!
-
-  """Fetches an object given its globally unique \`ID\`."""
-  node(
-    """The globally unique \`ID\`."""
-    nodeId: ID!
-  ): Node
-
   """Reads a set of \`Email\`."""
   allEmailsList(
     """Only read the first \`n\` values of the set."""

__tests__/__snapshots__/schema.test.ts.snap

@@ -59,23 +59,6 @@ interface Node {
 
 \\"\\"\\"The root query type which gives access points into the data universe.\\"\\"\\"
 type Query {
-  \\"\\"\\"
-  Exposes the root query type nested one level down. This is helpful for Relay 1
-  which can only query top level fields if they are in a particular form.
-  \\"\\"\\"
-  query: Query!
-
-  \\"\\"\\"
-  The root query type must be a \`Node\` to work well with Relay 1 mutations. This just resolves to \`query\`.
-  \\"\\"\\"
-  nodeId: ID!
-
-  \\"\\"\\"Fetches an object given its globally unique \`ID\`.\\"\\"\\"
-  node(
-    \\"\\"\\"The globally unique \`ID\`.\\"\\"\\"
-    nodeId: ID!
-  ): Node
-
   \\"\\"\\"Reads a set of \`Email\`.\\"\\"\\"
   allEmailsList(
     \\"\\"\\"Only read the first \`n\` values of the set.\\"\\"\\"
@@ -255,24 +238,7 @@ directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
 directive @key(fields: _FieldSet!) on OBJECT | INTERFACE
 
 """The root query type which gives access points into the data universe."""
-type Query implements Node {
-  """
-  Exposes the root query type nested one level down. This is helpful for Relay 1
-  which can only query top level fields if they are in a particular form.
-  """
-  query: Query!
-
-  """
-  The root query type must be a \`Node\` to work well with Relay 1 mutations. This just resolves to \`query\`.
-  """
-  nodeId: ID!
-
-  """Fetches an object given its globally unique \`ID\`."""
-  node(
-    """The globally unique \`ID\`."""
-    nodeId: ID!
-  ): Node
-
+type Query {
   """Reads a set of \`Email\`."""
   allEmailsList(
     """Only read the first \`n\` values of the set."""
@@ -360,14 +326,6 @@ type Query implements Node {
   _service: _Service! @deprecated(reason: "Only Apollo Federation should use this")
 }
 
-"""An object with a globally unique \`ID\`."""
-interface Node {
-  """
-  A globally unique identifier. Can be used in various places throughout the system to identify this single value.
-  """
-  nodeId: ID!
-}
-
 type Email implements Node {
   """
   A globally unique identifier. Can be used in various places throughout the system to identify this single value.
@@ -394,6 +352,14 @@ type Email implements Node {
   ): [UsersEmail!]!
 }
 
+"""An object with a globally unique \`ID\`."""
+interface Node {
+  """
+  A globally unique identifier. Can be used in various places throughout the system to identify this single value.
+  """
+  nodeId: ID!
+}
+
 type UsersEmail implements Node {
   """
   A globally unique identifier. Can be used in various places throughout the system to identify this single value.

src/index.ts

@@ -202,8 +202,41 @@ const AddKeyPlugin: Plugin = builder => {
   });
 };
 
-// Our federation implementation combines these two plugins:
+/*
+ * This plugin remove query/node/nodeId fields and Node interface from Query type to
+ * fix `GraphQLSchemaValidationError: There can be only one type named "query/node/nodeId"` error.
+ * This helps Apollo Gateway to consume two or more PostGraphile services.
+ */
+
+const RemoveQueryLegacyFeaturesPlugin: Plugin = builder => {
+  builder.hook('GraphQLObjectType:fields', (fields, _, context) => {
+    const {
+      scope: { isRootQuery },
+    } = context;
+
+    // Deleting the query, node, nodeId fields from the Query type that are used by
+    // the old relay specification which are not needed for modern GraphQL clients
+    if (isRootQuery) {
+      delete fields.query;
+      delete fields.node;
+      delete fields.nodeId;
+    }
+
+    return fields;
+  });
+
+  builder.hook('GraphQLObjectType:interfaces', (interfaces, _, context) => {
+    if (!context.scope.isRootQuery) {
+      return interfaces;
+    }
+    // Delete all interfaces (i.e. the Node interface) from Query.
+    return [];
+  });
+};
+
+// Our federation implementation combines these plugins:
 export default makePluginByCombiningPlugins(
   SchemaExtensionPlugin,
-  AddKeyPlugin
+  AddKeyPlugin,
+  RemoveQueryLegacyFeaturesPlugin,
 );