Learn TypeScript w/ Mike North

Imported Resolver

March 24, 2022

Table of Contents

In this chapter, we’ll get both our schema and resolver out of the apollo-server.ts file. Ideal

Getting the schema out

Go back to the server/src/apollo-server.ts file take everything in the gql string template, and put it in a file called schema.graphql in the root of the project (the repo root)

graphql
# schema.graphql
type Query {
currentUser: User!
suggestions: [Suggestion!]!
}
type User {
id: String!
name: String!
handle: String!
coverUrl: String!
avatarUrl: String!
createdAt: String!
updatedAt: String!
}
type Suggestion {
name: String!
handle: String!
avatarUrl: String!
reason: String!
}

Next go back to server/src/apollo-server.ts so we can import this file as our schema

Add the following imports

ts
import { GraphQLFileLoader } from "@graphql-tools/graphql-file-loader"
import { loadSchemaSync } from "@graphql-tools/load"
import { addResolversToSchema } from "@graphql-tools/schema"
import { GRAPHQL_SCHEMA_PATH } from "./constants"

This GRAPHQL_SCHEMA_PATH variable is the path of the schema.graphql file you just created

Next add this code right below the imports, in top-level module scope

ts
const SCHEMA = loadSchemaSync(GRAPHQL_SCHEMA_PATH, {
loaders: [new GraphQLFileLoader()],
})

And then where you’re instantiating your ApolloServer

diff
const server = new ApolloServer({
- typeDefs,
+ schema: addResolversToSchema({
+ schema: SCHEMA,
+ }),
context: () => ({ db }),
plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],

You should be able to start up the server again, try this simple query again

graphql
query CurrentUser {
currentUser {
name
}
}

and get the same result as before

json
{
"data": {
"currentUser": {
"name": "John Doe"
}
}
}
Try

Getting the resolvers out

Create a new file in your project server/src/resolvers.ts.

Move the value held by the resolvers variable into this file, and make that value the default export

ts
const resolvers = {
Query: {
currentUser: () => {
return {
id: "123",
name: "John Doe",
handle: "johndoe",
coverUrl: "",
avatarUrl: "",
createdAt: "",
updatedAt: "",
}
},
suggestions: () => {
return []
},
},
}
export default resolvers

Go back to server/src/apollo-server.ts and add the following import

ts
import resolvers from "./resolvers"

Test the query again in Apollo explorer, and it should still work.

Breaking up your resolver

If we keep this resolvers.ts as one big file, things will get unmanageable quickly. We can break establish a pattern for breaking this file up into sub-parts

Create a new folder server/src/resolvers and a new file server/src/resolvers/Query.ts.

Move the object containing the Query: family of resolvers (Query.currentUser, Query.suggestions) into this new file

ts
const queryTwitterResolvers = {
currentUser: () => {
return {
id: "123",
name: "John Doe",
handle: "johndoe",
coverUrl: "",
avatarUrl: "",
createdAt: "",
updatedAt: "",
}
},
suggestions: () => {
return []
},
}
export default queryTwitterResolvers

Finally, in your server/src/resolvers.ts, import this object, and wire it up where it was before

ts
import queryTwitterResolvers from "./resolvers/Query"
const resolvers = {
Query: queryTwitterResolvers,
}
export default resolvers

Test the example query in Apollo explorer one last time to make sure everything works.

Next, let’s add some types before things get any more complicated!



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