add implementation to support streaming uploaded file from GraphQL over to REST endpoint

Signed-off-by: Eyo O. Eyo <[email protected]>
Signed-off-by: Eyo Okon Eyo <[email protected]>

Author: eokoneyo

packages/openapi-to-graphql/package.json

@@ -122,6 +122,7 @@
     "isomorphic-git": "^1.9.2",
     "jest": "^27.0.6",
     "js-yaml": "^4.1.0",
+    "memfs": "^3.4.0",
     "mqemitter": "^4.4.0",
     "mqtt": "^4.2.1",
     "nodemon": "^2.0.12",

packages/openapi-to-graphql/src/resolver_builder.ts

@@ -18,6 +18,7 @@ import crossFetch from 'cross-fetch'
 import { FileUpload } from 'graphql-upload'
 
 // Imports:
+import stream from 'stream'
 import * as Oas3Tools from './oas_3_tools'
 import { JSONPath } from 'jsonpath-plus'
 import { debug } from 'debug'
@@ -32,6 +33,7 @@ const pubsub = new PubSub()
 const translationLog = debug('translation')
 const httpLog = debug('http')
 const pubsubLog = debug('pubsub')
+const uploadLog = debug('fileUpload')
 
 // OAS runtime expression reference locations
 const RUNTIME_REFERENCES = ['header.', 'query.', 'path.', 'body']
@@ -325,7 +327,7 @@ export function getPublishResolver<TSource, TContext, TArgs>({
  * If the operation type is Query or Mutation, create and return a resolver
  * function that performs API requests for the given GraphQL query
  */
-export function getResolver<TSource, TContext, TArgs>({
+export function getResolver<TSource, TContext, TArgs> ({
   operation,
   argsFromLink = {},
   payloadName,
@@ -578,13 +580,40 @@ export function getResolver<TSource, TContext, TArgs>({
       } else if (operation.payloadContentType === 'multipart/form-data') {
         form = new FormData()
 
-        Object.entries(args[sanePayloadName]).forEach(([key, value]) => {
-          // if (typeof value === 'object' && (value as Partial<FileUpload>).createReadStream) {
-          //   form.append(key, (value as FileUpload).createReadStream())
-          // }
+        const formFieldsPayloadEntries = Object.entries(args[sanePayloadName]);
 
-          form.append(key, value)
-        })
+        (await Promise.all(formFieldsPayloadEntries.map(([_, v]) => v)))
+            .forEach((fieldValue, idx) => {
+              const fieldName = formFieldsPayloadEntries[idx][0]
+
+              if (typeof fieldValue === 'object' && Boolean((fieldValue as Partial<FileUpload>).createReadStream)) {
+                const uploadingFile = fieldValue as FileUpload
+                const originalFileStream = uploadingFile.createReadStream()
+                const filePassThrough = new stream.PassThrough()
+
+                originalFileStream.on('readable', function () {
+                  let data
+                  // tslint:disable-next-line:no-conditional-assignment
+                  while (data = this.read()) {
+                    filePassThrough.write(data)
+                  }
+                })
+
+                originalFileStream.on('end', () => {
+                  uploadLog(`Upload for received file ${uploadingFile.filename} completed`)
+                  filePassThrough.end()
+                })
+
+                uploadLog(`Queuing upload for received file ${uploadingFile.filename}`)
+
+                form.append(fieldName, filePassThrough, {
+                  filename: uploadingFile.filename,
+                  contentType: uploadingFile.mimetype
+                })
+              } else {
+                form.append(fieldName, fieldValue)
+              }
+            })
 
         rawPayload = form
       } else {
@@ -672,6 +701,11 @@ export function getResolver<TSource, TContext, TArgs>({
 
     let response: Response
     try {
+      // if is form, remove default content type and
+      // let fetch compute appropriate header content-type based off of form data
+      if (form) {
+        delete options.headers['content-type']
+      }
       response = await fetch(url.toString(), options)
     } catch (err) {
       httpLog(err)

packages/openapi-to-graphql/yarn.lock

@@ -2525,6 +2525,11 @@ fs-capacitor@^6.2.0:
   resolved "https://registry.yarnpkg.com/fs-capacitor/-/fs-capacitor-6.2.0.tgz#fa79ac6576629163cb84561995602d8999afb7f5"
   integrity sha512-nKcE1UduoSKX27NSZlg879LdQc94OtbOsEmKMN2MBNudXREvijRKx2GEBsTMTfws+BrbkJoEuynbGSVRSpauvw==
 
+[email protected]:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/fs-monkey/-/fs-monkey-1.0.3.tgz#ae3ac92d53bb328efe0e9a1d9541f6ad8d48e2d3"
+  integrity sha512-cybjIfiiE+pTWicSCLFHSrXZ6EilF30oh91FDP9S2B051prEa7QWfrVTQm10/dDpswBDXZugPa1Ogu8Yh+HV0Q==
+
 fs.realpath@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
@@ -4013,6 +4018,13 @@ [email protected]:
   resolved "https://registry.yarnpkg.com/media-typer/-/media-typer-0.3.0.tgz#8710d7af0aa626f8fffa1ce00168545263255748"
   integrity sha1-hxDXrwqmJvj/+hzgAWhUUmMlV0g=
 
+memfs@^3.4.0:
+  version "3.4.0"
+  resolved "https://registry.yarnpkg.com/memfs/-/memfs-3.4.0.tgz#8bc12062b973be6b295d4340595736a656f0a257"
+  integrity sha512-o/RfP0J1d03YwsAxyHxAYs2kyJp55AFkMazlFAZFR2I2IXkxiUTXRabJ6RmNNCQ83LAD2jy52Khj0m3OffpNdA==
+  dependencies:
+    fs-monkey "1.0.3"
+
 [email protected]:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/merge-descriptors/-/merge-descriptors-1.0.1.tgz#b00aaa556dd8b44568150ec9d1b953f3f90cbb61"