support type extensions in schema files

packages/apollo-language-server/src/providers/schema/file.ts

@@ -4,12 +4,14 @@ import {
   buildClientSchema,
   Source,
   buildSchema,
-  printSchema
+  printSchema,
+  parse
 } from "graphql";
 import { readFileSync } from "fs";
 import { extname, resolve } from "path";
 import { GraphQLSchemaProvider, SchemaChangeUnsubscribeHandler } from "./base";
 import { NotificationHandler } from "vscode-languageserver";
+import { buildSchemaFromSDL } from "apollo-graphql";
 
 export interface FileSchemaProviderConfig {
   path?: string;
@@ -26,27 +28,27 @@ export class FileSchemaProvider implements GraphQLSchemaProvider {
     const { path, paths } = this.config;
 
     // load each path and get sdl string from each, if a list, concatenate them all
-    const sdlResults = path
-      ? this.loadFileAndGetSDL(path)
+    const documents = path
+      ? [this.loadFileAndGetDocument(path)]
       : paths
-      ? paths.map(this.loadFileAndGetSDL).join("\n")
+      ? paths.map(this.loadFileAndGetDocument)
       : undefined;
 
-    if (!sdlResults)
+    if (!documents)
       throw new Error(
         `Schema could not be loaded for [${
           path ? path : paths ? paths.join(", ") : "undefined"
         }]`
       );
 
-    this.schema = buildSchema(sdlResults);
+    this.schema = buildSchemaFromSDL(documents);
 
     if (!this.schema) throw new Error(`Schema could not be loaded for ${path}`);
     return this.schema;
   }
 
-  // load a graphql file or introspection result and return the SDL version
-  loadFileAndGetSDL(path: string) {
+  // load a graphql file or introspection result and return the GraphQL DocumentNode
+  loadFileAndGetDocument(path: string) {
     let result;
     try {
       result = readFileSync(path, {
@@ -68,9 +70,9 @@ export class FileSchemaProvider implements GraphQLSchemaProvider {
         : parsed;
 
       const schema = buildClientSchema({ __schema });
-      return printSchema(schema);
+      return parse(printSchema(schema));
     } else if (ext === ".graphql" || ext === ".graphqls" || ext === ".gql") {
-      return result;
+      return parse(result);
     }
     throw new Error(
       "File Type not supported for schema loading. Must be a .json, .graphql, .gql, or .graphqls file"