Improve readme

src/main/java/io/github/mstachniuk/graphqljavaexample/graphql/codefirst/CodeFirstConfiguration.java

@@ -4,6 +4,7 @@
 import io.github.mstachniuk.graphqljavaexample.company.CompanyDataFetcher;
 import io.github.mstachniuk.graphqljavaexample.customer.*;
 import io.github.mstachniuk.graphqljavaexample.item.ItemDataFetcher;
+import io.github.mstachniuk.graphqljavaexample.node.NodeResolver;
 import io.github.mstachniuk.graphqljavaexample.order.OrderDataFetcher;
 import io.github.mstachniuk.graphqljavaexample.search.SearchDataFetcher;
 import io.github.mstachniuk.graphqljavaexample.search.SearchResultResolver;
@@ -66,6 +67,7 @@ private GraphQLFieldDefinition customerDefinition() {
                         .name("id")
                         .type(new GraphQLNonNull(GraphQLString)))
                 .type(new GraphQLNonNull(GraphQLObjectType.newObject()
+                        .withInterface(nodeInterfaceDefinition())
                         .name("Customer")
                         .field(GraphQLFieldDefinition.newFieldDefinition()
                                 .name("id")
@@ -390,4 +392,15 @@ private GraphQLFieldDefinition searchDefinition() {
                 .dataFetcher(searchDataFetcher)
                 .build();
     }
+
+    private GraphQLInterfaceType nodeInterfaceDefinition() {
+        return GraphQLInterfaceType.newInterface()
+                .name("Node")
+                .field(GraphQLFieldDefinition.newFieldDefinition()
+                        .name("id")
+                        .type(new GraphQLNonNull(GraphQLID))
+                        .build())
+                .typeResolver(new NodeResolver())
+                .build();
+    }
 }

src/main/java/io/github/mstachniuk/graphqljavaexample/node/NodeResolver.java

@@ -0,0 +1,12 @@
+package io.github.mstachniuk.graphqljavaexample.node;
+
+import graphql.TypeResolutionEnvironment;
+import graphql.schema.GraphQLObjectType;
+import graphql.schema.TypeResolver;
+
+public class NodeResolver implements TypeResolver {
+    @Override
+    public GraphQLObjectType getType(TypeResolutionEnvironment env) {
+        return null;
+    }
+}

src/main/resources/graphql/model.graphqls

@@ -7,7 +7,7 @@ type Customer {
     orders: [Order]
 }
 
-type Company {
+type Company implements Node {
     id: ID!
     name: String!
     website: String!
@@ -23,7 +23,7 @@ enum Status {
     NEW, CANCELED, DONE
 }
 
-type Item {
+type Item implements Node {
     id: ID!
     name: String!
     amount: Int
@@ -87,18 +87,24 @@ interface User {
     email: String!
 }
 
-type Admin implements User {
+type Admin implements Node & User {
     id: ID!
     name: String!
     email: String!
     superAdmin: Boolean!
 }
 
-type Moderator implements User {
+type Moderator implements Node & User {
     id: ID!
     name: String!
     email: String!
     permissions: [String]
 }
 
 union SearchResult = Customer | Admin | Moderator
+
+#An object with an ID
+interface Node {
+    #The ID of an object
+    id: ID!
+}