fix: #670 - explicit nullability for connectionPlugin (#671)

Author: tgriesser

src/plugins/connectionPlugin.ts

@@ -1,5 +1,5 @@
 import { GraphQLFieldResolver, GraphQLResolveInfo } from 'graphql'
-import { arg, ArgsRecord, intArg } from '../definitions/args'
+import { ArgsRecord, intArg, stringArg } from '../definitions/args'
 import { CommonFieldConfig, FieldOutConfig } from '../definitions/definitionBlocks'
 import { nonNull } from '../definitions/nonNull'
 import { ObjectDefinitionBlock, objectType } from '../definitions/objectType'
@@ -272,14 +272,10 @@ export type ConnectionFieldConfig<TypeName extends string = any, FieldName exten
   NexusGenPluginFieldConfig<TypeName, FieldName>
 
 const ForwardPaginateArgs = {
-  first: arg({
-    type: 'Int',
-    description: 'Returns the first n elements from the list.',
-  }),
-  after: arg({
-    type: 'String',
-    description: 'Returns the elements in the list that come after the specified cursor',
-  }),
+  first: nullable(intArg({ description: 'Returns the first n elements from the list.' })),
+  after: nullable(
+    stringArg({ description: 'Returns the elements in the list that come after the specified cursor' })
+  ),
 }
 
 const ForwardOnlyStrictArgs = {
@@ -288,14 +284,10 @@ const ForwardOnlyStrictArgs = {
 }
 
 const BackwardPaginateArgs = {
-  last: arg({
-    type: 'Int',
-    description: 'Returns the last n elements from the list.',
-  }),
-  before: arg({
-    type: 'String',
-    description: 'Returns the elements in the list that come before the specified cursor',
-  }),
+  last: nullable(intArg({ description: 'Returns the last n elements from the list.' })),
+  before: nullable(
+    stringArg({ description: 'Returns the elements in the list that come before the specified cursor' })
+  ),
 }
 
 const BackwardOnlyStrictArgs = {
@@ -503,11 +495,11 @@ export const connectionPlugin = (connectionPluginConfig?: ConnectionPluginConfig
                       type: 'Boolean',
                       description: `Used to indicate whether more edges exist prior to the set defined by the clients arguments.`,
                     })
-                    t2.field('startCursor', {
+                    t2.nullable.field('startCursor', {
                       type: 'String',
                       description: `The cursor corresponding to the first nodes in edges. Null if the connection is empty.`,
                     })
-                    t2.field('endCursor', {
+                    t2.nullable.field('endCursor', {
                       type: 'String',
                       description: `The cursor corresponding to the last nodes in edges. Null if the connection is empty.`,
                     })

tests/plugins/__snapshots__/connectionPlugin.spec.ts.snap

@@ -231,6 +231,75 @@ type PageInfo {
 }"
 `;
 
+exports[`field level configuration #670 should explicitly state nullability for connectionPlugin args & fields 1`] = `
+"type Query {
+  users(
+    \\"\\"\\"Returns the first n elements from the list.\\"\\"\\"
+    first: Int
+
+    \\"\\"\\"Returns the elements in the list that come after the specified cursor\\"\\"\\"
+    after: String
+
+    \\"\\"\\"Returns the last n elements from the list.\\"\\"\\"
+    last: Int
+
+    \\"\\"\\"Returns the elements in the list that come before the specified cursor\\"\\"\\"
+    before: String
+  ): UserConnection!
+}
+
+type UserConnection {
+  \\"\\"\\"
+  https://facebook.github.io/relay/graphql/connections.htm#sec-Edge-Types
+  \\"\\"\\"
+  edges: [UserEdge!]!
+
+  \\"\\"\\"
+  https://facebook.github.io/relay/graphql/connections.htm#sec-undefined.PageInfo
+  \\"\\"\\"
+  pageInfo: PageInfo!
+}
+
+type UserEdge {
+  \\"\\"\\"https://facebook.github.io/relay/graphql/connections.htm#sec-Cursor\\"\\"\\"
+  cursor: String!
+
+  \\"\\"\\"https://facebook.github.io/relay/graphql/connections.htm#sec-Node\\"\\"\\"
+  node: User!
+}
+
+\\"\\"\\"
+PageInfo cursor, as defined in https://facebook.github.io/relay/graphql/connections.htm#sec-undefined.PageInfo
+\\"\\"\\"
+type PageInfo {
+  \\"\\"\\"
+  Used to indicate whether more edges exist following the set defined by the clients arguments.
+  \\"\\"\\"
+  hasNextPage: Boolean!
+
+  \\"\\"\\"
+  Used to indicate whether more edges exist prior to the set defined by the clients arguments.
+  \\"\\"\\"
+  hasPreviousPage: Boolean!
+
+  \\"\\"\\"
+  The cursor corresponding to the first nodes in edges. Null if the connection is empty.
+  \\"\\"\\"
+  startCursor: String
+
+  \\"\\"\\"
+  The cursor corresponding to the last nodes in edges. Null if the connection is empty.
+  \\"\\"\\"
+  endCursor: String
+}
+
+type User {
+  id: ID!
+  name: String!
+}
+"
+`;
+
 exports[`field level configuration can configure the connection per-instance 1`] = `
 "type QueryUsers_Connection {
   \\"\\"\\"

tests/plugins/connectionPlugin.spec.ts

@@ -829,4 +829,31 @@ describe('field level configuration', () => {
     const regExp = /interface NexusGenCustomOutputMethods(?:.*) {((.|\n)*?)}/
     expect(regExp.exec(tsTypes)?.[1]).toMatchSnapshot()
   })
+
+  it('#670 should explicitly state nullability for connectionPlugin args & fields', async () => {
+    const { schema } = await generateSchema.withArtifacts({
+      outputs: false,
+      types: [
+        objectType({
+          name: 'Query',
+          definition(t) {
+            // @ts-ignore
+            t.connectionField('users', {
+              type: User,
+              nodes(root: any, args: any, ctx: any, info: any) {
+                return userNodes
+              },
+            })
+          },
+        }),
+      ],
+      plugins: [connectionPlugin()],
+      nonNullDefaults: {
+        input: true,
+        output: true,
+      },
+    })
+
+    expect(printSchema(schema)).toMatchSnapshot()
+  })
 })