Pass collections to constructor

Author: lorensr

README.md

@@ -32,24 +32,27 @@ This package uses [DataLoader](https://github.com/graphql/dataloader) for batchi
 
 ### Basic
 
-The basic setup is subclassing `MongoDataSource`, setting your collections in the constructor, and then using the [API methods](#API):
+The basic setup is subclassing `MongoDataSource`, passing your collection(s) to the constructor, and using the [API methods](#API):
 
 ```js
 import { MongoDataSource } from 'apollo-datasource-mongodb'
 
 class MyMongo extends MongoDataSource {
-  constructor() {
-    super()
-    this.collections = { users, posts }
-  }
-
   getUser(userId) {
     return this.users.findOneById(userId)
   }
 }
+
+const server = new ApolloServer({
+  typeDefs,
+  resolvers,
+  dataSources: () => ({
+    db: new MyMongo({ users, posts })
+  })
+})
 ```
 
-The request's context is available at `this.context`. For example, if you put the logged-in user's ID on context as `context.currentUserId`:
+The collections are available at `this.collections` (e.g. `this.collections.users.update({_id: 'foo, { $set: { name: 'me' }}})`). The request's context is available at `this.context`. For example, if you put the logged-in user's ID on context as `context.currentUserId`:
 
 ```js
 class MyMongo extends MongoDataSource {
@@ -69,11 +72,6 @@ If you want to implement an initialize method, it must call the parent method:
 
 ```js
 class MyMongo extends MongoDataSource {
-  constructor() {
-    super()
-    this.collections = { users, posts }
-  }
-
   initialize(config) {
     super.initialize(config)
     ...
@@ -101,11 +99,6 @@ client.connect(e => {
 })
 
 class MyMongo extends MongoDataSource {
-  constructor() {
-    super()
-    this.collections = { users, posts }
-  }
-
   getUser(userId) {
     return this.users.findOneById(userId)
   }
@@ -128,7 +121,7 @@ const server = new ApolloServer({
   typeDefs,
   resolvers,
   dataSources: () => ({
-    db: new MyMongo()
+    db: new MyMongo({ users, posts })
   })
 })
 ```

src/__tests__/datasource.test.js

@@ -4,34 +4,16 @@ const users = {}
 const posts = {}
 
 class MyMongo extends MongoDataSource {
-  constructor() {
-    super()
-    this.collections = { users, posts }
-  }
-
   initialize(config) {
     super.initialize(config)
   }
 }
 
-class SingleCollection extends MongoDataSource {
-  constructor() {
-    super()
-    this.collection = users
-  }
-}
-
 describe('MongoDataSource', () => {
   it('sets up caching functions', () => {
-    const source = new MyMongo()
+    const source = new MyMongo({ users, posts })
     source.initialize({})
     expect(source.users.findOneById).toBeDefined()
     expect(source.posts.findOneById).toBeDefined()
   })
-
-  it('sets up caching functions for single collection', () => {
-    const source = new SingleCollection()
-    source.initialize({})
-    expect(source.findOneById).toBeDefined()
-  })
 })

src/datasource.js

@@ -5,33 +5,30 @@ import { InMemoryLRUCache } from 'apollo-server-caching'
 import { createCachingMethods } from './cache'
 
 class MongoDataSource extends DataSource {
-  // https://github.com/apollographql/apollo-server/blob/master/packages/apollo-datasource/src/index.ts
-  initialize(config) {
-    this.context = config.context
+  constructor(collections) {
+    super()
 
-    const setUpCorrectly =
-      typeof this.collections === 'object' || this.collection
+    const setUpCorrectly = typeof collections === 'object'
     if (!setUpCorrectly) {
       throw new ApolloError(
-        'Child class of MongoDataSource must set this.collections or this.collection in constructor'
+        'MongoDataSource constructor must be given an object with collection(s)'
       )
     }
 
+    this.collections = collections
+  }
+
+  // https://github.com/apollographql/apollo-server/blob/master/packages/apollo-datasource/src/index.ts
+  initialize(config) {
+    this.context = config.context
+
     const cache = config.cache || new InMemoryLRUCache()
 
-    if (this.collections) {
-      for (const key in this.collections) {
-        this[key] = createCachingMethods({
-          collection: this.collections[key],
-          cache
-        })
-      }
-    } else {
-      const methods = createCachingMethods({
-        collection: this.collection,
+    for (const key in this.collections) {
+      this[key] = createCachingMethods({
+        collection: this.collections[key],
         cache
       })
-      Object.assign(this, methods)
     }
   }
 }