Basic GQL server with mock data.

package.json

@@ -18,7 +18,13 @@
   },
   "homepage": "https://github.com/vulcanize/erc20-watcher#readme",
   "dependencies": {
-    "express": "^4.17.1"
+    "@types/lodash": "^4.14.168",
+    "express": "^4.17.1",
+    "express-graphql": "^0.12.0",
+    "graphql": "^15.5.0",
+    "graphql-import-node": "^0.0.4",
+    "graphql-tools": "^7.0.4",
+    "lodash": "^4.17.21"
   },
   "devDependencies": {
     "@types/express": "^4.17.11",

src/erc20.graphql

@@ -0,0 +1,29 @@
+type Author {
+  id: Int!
+  firstName: String
+  lastName: String
+  """
+  the list of Posts by this author
+  """
+  posts: [Post]
+}
+
+type Post {
+  id: Int!
+  title: String
+  author: Author
+  votes: Int
+}
+
+# the schema allows the following query:
+type Query {
+  posts: [Post]
+  author(id: Int!): Author
+}
+
+# this schema allows the following mutation:
+type Mutation {
+  upvotePost (
+    postId: Int!
+  ): Post
+}

src/gql.ts

@@ -0,0 +1,39 @@
+import 'graphql-import-node';
+import { find, filter } from 'lodash';
+import { makeExecutableSchema } from '@graphql-tools/schema';
+
+import * as typeDefs from './erc20.graphql';
+import data from './mock-data';
+
+const { posts, authors } = data;
+
+const resolvers = {
+  Query: {
+    posts: () => posts,
+    author: (_, { id }) => find(authors, { id }),
+  },
+
+  Mutation: {
+    upvotePost: (_, { postId }) => {
+      const post = find(posts, { id: postId });
+      if (!post) {
+        throw new Error(`Couldn't find post with id ${postId}`);
+      }
+      post.votes += 1;
+      return post;
+    },
+  },
+
+  Author: {
+    posts: author => filter(posts, { authorId: author.id }),
+  },
+
+  Post: {
+    author: post => find(authors, { id: post.authorId }),
+  },
+};
+
+export const schema = makeExecutableSchema({
+  typeDefs,
+  resolvers
+});

src/mock-data.ts

@@ -0,0 +1,17 @@
+const authors = [
+  { id: 1, firstName: 'Tom', lastName: 'Coleman' },
+  { id: 2, firstName: 'Sashko', lastName: 'Stubailo' },
+  { id: 3, firstName: 'Mikhail', lastName: 'Novikov' },
+];
+
+const posts = [
+  { id: 1, authorId: 1, title: 'Introduction to GraphQL', votes: 2 },
+  { id: 2, authorId: 2, title: 'Welcome to Meteor', votes: 3 },
+  { id: 3, authorId: 2, title: 'Advanced GraphQL', votes: 1 },
+  { id: 4, authorId: 3, title: 'Launchpad is Cool', votes: 7 },
+];
+
+export default {
+  posts,
+  authors
+};

src/server.ts

@@ -1,13 +1,25 @@
 import express, { Application, Request, Response } from 'express';
+import { graphqlHTTP } from 'express-graphql';
+
+import { schema } from './gql';
 
 const app: Application = express();
 
+// TODO: Accept CLI param for host and port.
 const port: number = 3001;
 
+app.use(
+  '/graphql',
+  graphqlHTTP({
+    schema,
+    graphiql: true,
+  }),
+);
+
 app.get('/', (req: Request, res: Response) => {
-  res.send('Hello world');
+  res.send('ERC20 Watcher');
 });
 
-app.listen(port, function () {
-  console.log(`App is listening on port ${port} !`);
+app.listen(port, () => {
+  console.log(`Server is listening on port ${port}`);
 });

tsconfig.json

@@ -25,7 +25,7 @@
     // "isolatedModules": true,                     /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
 
     /* Strict Type-Checking Options */
-    "strict": true,                                 /* Enable all strict type-checking options. */
+    "strict": false,                                 /* Enable all strict type-checking options. */
     // "noImplicitAny": true,                       /* Raise error on expressions and declarations with an implied 'any' type. */
     // "strictNullChecks": true,                    /* Enable strict null checks. */
     // "strictFunctionTypes": true,                 /* Enable strict checking of function types. */