fix: Add GraphQLInterfaceType inside buildInfoForAllScalars

fix: Add GraphQLInterfaceType inside buildInfoForAllScalars

fix: Maybe type from codegen folder

Author: XBeg9

src/codegen/TypescriptGenerator.ts

@@ -18,6 +18,7 @@ import {
 } from 'graphql'
 
 import { Generator } from './Generator'
+
 import { Maybe } from './types'
 
 export class TypescriptGenerator extends Generator {

src/info.test.ts

@@ -66,6 +66,31 @@ test('buildInfoForAllScalars: excludes object type fields', t => {
   t.is(info.fieldName, 'book')
 })
 
+test('buildInfoForAllScalars: support interfaces', t => {
+  const schema = buildSchema(`
+  type Query {
+    book: IBook
+  }
+
+  type Book implements IBook {
+    title: String
+    number: Float
+    otherBook: IBook
+  }
+
+  interface IBook {
+    title: String
+    number: Float
+    otherBook: Book
+  }
+  `)
+  const info = buildInfoForAllScalars('book', schema, 'query')
+  const selections = info.fieldNodes[0].selectionSet!.selections
+
+  assertFields(t, selections, ['title', 'number'])
+  t.is(info.fieldName, 'book')
+})
+
 test('buildInfoForAllScalars: enums', t => {
   const schema = buildSchema(`
   type Query {

src/info.ts

@@ -12,6 +12,9 @@ import {
   print,
   parse,
   validate,
+  isObjectType,
+  isInterfaceType,
+  isScalarType,
 } from 'graphql'
 
 import { Operation } from './types'
@@ -45,7 +48,7 @@ export function buildInfoForAllScalars(
   const namedType = getNamedType(type)
 
   let selections: FieldNode[] | undefined
-  if (namedType instanceof GraphQLObjectType) {
+  if (isInterfaceType(namedType) || isObjectType(namedType)) {
     const fields = (namedType as any).getFields()
     selections = Object.keys(fields)
       .filter(f => isScalar(fields[f].type))
@@ -161,7 +164,7 @@ export function makeSubInfo(
   fragment?: string,
 ): GraphQLResolveInfo | null {
   const returnType = getDeepType(info.returnType)
-  if (returnType instanceof GraphQLScalarType) {
+  if (isScalarType(returnType)) {
     throw new Error(`Can't make subInfo for type ${info.returnType.toString()}`)
   }
 
@@ -178,7 +181,7 @@ export function makeSubInfo(
 
   while (fieldsToTraverse.length > 0) {
     currentFieldName = fieldsToTraverse.shift()!
-    if (!(currentType instanceof GraphQLObjectType)) {
+    if (!isObjectType(currentType)) {
       throw new Error(
         `Can't get subInfo for type ${currentType.toString()} as needs to be a GraphQLObjectType`,
       )
@@ -192,7 +195,7 @@ export function makeSubInfo(
     }
 
     const currentFieldType = fields[currentFieldName].type
-    if (!(currentFieldType instanceof GraphQLObjectType)) {
+    if (!isObjectType(currentFieldType)) {
       throw new Error(
         `Can't get subInfo for type ${currentFieldType} of field ${currentFieldName} on type ${currentType.toString()}`,
       )