jaydenseric · jaydenseric · Mar 15, 2020 · Feb 23, 2020 · Mar 5, 2020 · Mar 9, 2020
diff --git a/changelog.md b/changelog.md
@@ -7,6 +7,17 @@
 - Updated Node.js support from v8.10+ to v10+.
 - Updated dependencies, some of which require Node.js v10+.
 
+### Minor
+
+- Support uploading files from a server environment, fixing [#172](https://github.com/jaydenseric/apollo-upload-client/issues/172) via [#179](https://github.com/jaydenseric/apollo-upload-client/pull/179).
+  - Added `createUploadLink` options:
+    - `isExtractableFile`
+    - `FormData`
+    - `formDataAppendFile`
+  - Added exports for the new `createUploadLink` option defaults:
+    - `isExtractableFile`
+    - `formDataAppendFile`
+
 ### Patch
 
 - Removed the now redundant [`eslint-plugin-import-order-alphabetical`](https://npm.im/eslint-plugin-import-order-alphabetical) dev dependency.

diff --git a/readme.md b/readme.md
@@ -121,16 +121,24 @@ Consider polyfilling:
 
 - [class ReactNativeFile](#class-reactnativefile)
 - [function createUploadLink](#function-createuploadlink)
+- [function formDataAppendFile](#function-formdataappendfile)
+- [function isExtractableFile](#function-isextractablefile)
+- [type ExtractableFileMatcher](#type-extractablefilematcher)
 - [type FetchOptions](#type-fetchoptions)
+- [type FormDataFileAppender](#type-formdatafileappender)
 - [type ReactNativeFileSubstitute](#type-reactnativefilesubstitute)
 
 ### class ReactNativeFile
 
-Used to mark a [React Native `File` substitute](#type-reactnativefilesubstitute). It’s too risky to assume all objects with `uri`, `type` and `name` properties are files to extract. Re-exported from [`extract-files`](https://npm.im/extract-files) for convenience.
+Used to mark [React Native `File` substitutes](#type-reactnativefilesubstitute) as it’s too risky to assume all objects with `uri`, `type` and `name` properties are extractable files.
 
 | Parameter | Type | Description |
 | :-- | :-- | :-- |
-| `file` | [ReactNativeFileSubstitute](#type-reactnativefilesubstitute) | A React Native [`File`](https://developer.mozilla.org/docs/web/api/file) substitute. |
+| `file` | [ReactNativeFileSubstitute](#type-reactnativefilesubstitute) | A React Native [`File`](https://developer.mozilla.org/en-US/docs/Web/API/File) substitute. |
+
+#### See
+
+- [`extract-files` `ReactNativeFile` docs](https://github.com/jaydenseric/extract-files#class-reactnativefile).
 
 #### Examples
 
@@ -150,14 +158,21 @@ _A React Native file that can be used in query or mutation variables._
 
 ### function createUploadLink
 
-Creates a terminating [Apollo Link](https://apollographql.com/docs/link) capable of file uploads. Options match [`createHttpLink`](https://apollographql.com/docs/link/links/http#options).
+Creates a terminating [Apollo Link](https://apollographql.com/docs/link) capable of file uploads.
+
+The link matches and extracts files in the GraphQL operation. If there are files it uses a [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance as the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch) `options.body` to make a [GraphQL multipart request](https://github.com/jaydenseric/graphql-multipart-request-spec), otherwise it sends a regular POST request.
+
+Some of the options are similar to the [`createHttpLink` options](https://www.apollographql.com/docs/link/links/http/#options).
 
 | Parameter | Type | Description |
 | :-- | :-- | :-- |
 | `options` | object | Options. |
 | `options.uri` | string? = /graphql | GraphQL endpoint URI. |
-| `options.fetch` | Function? | [`fetch`](https://fetch.spec.whatwg.org) implementation to use, defaulting to the `fetch` global. |
-| `options.fetchOptions` | [FetchOptions](#type-fetchoptions)? | `fetch` options; overridden by upload requirements. |
+| `options.isExtractableFile` | [ExtractableFileMatcher](#type-extractablefilematcher)? = [isExtractableFile](#function-isextractablefile) | Customizes how files are matched in the GraphQL operation for extraction. |
+| `options.FormData` | class? | [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) implementation to use, defaulting to the [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) global. |
+| `options.formDataAppendFile` | [FormDataFileAppender](#type-formdatafileappender)? = [formDataAppendFile](#function-formdataappendfile) | Customizes how extracted files are appended to the [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance. |
+| `options.fetch` | Function? | [`fetch`](https://fetch.spec.whatwg.org) implementation to use, defaulting to the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch) global. |
+| `options.fetchOptions` | [FetchOptions](#type-fetchoptions)? | [`fetch` options](#type-fetchoptions); overridden by upload requirements. |
 | `options.credentials` | string? | Overrides `options.fetchOptions.credentials`. |
 | `options.headers` | object? | Merges with and overrides `options.fetchOptions.headers`. |
 | `options.includeExtensions` | boolean? = `false` | Toggles sending `extensions` fields to the GraphQL server. |
@@ -186,6 +201,68 @@ _A basic Apollo Client setup._
 
 ---
 
+### function formDataAppendFile
+
+The default implementation for [`createUploadLink`](#function-createuploadlink) `options.formDataAppendFile` that uses the standard [`FormData.append`](https://developer.mozilla.org/en-US/docs/Web/API/FormData/append) method.
+
+**Type:** [FormDataFileAppender](#type-formdatafileappender)
+
+| Parameter | Type | Description |
+| :-- | :-- | :-- |
+| `formData` | FormData | [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance to append the specified file to. |
+| `fieldName` | string | Field name for the file. |
+| `file` | \* | File to append. |
+
+---
+
+### function isExtractableFile
+
+The default implementation for [`createUploadLink`](#function-createuploadlink) `options.isExtractableFile`.
+
+**Type:** [ExtractableFileMatcher](#type-extractablefilematcher)
+
+| Parameter | Type | Description     |
+| :-------- | :--- | :-------------- |
+| `value`   | \*   | Value to check. |
+
+**Returns:** boolean — Is the value an extractable file.
+
+#### See
+
+- [`extract-files` `isExtractableFile` docs](https://github.com/jaydenseric/extract-files#function-isextractablefile).
+
+---
+
+### type ExtractableFileMatcher
+
+A function that checks if a value is an extractable file.
+
+**Type:** Function
+
+| Parameter | Type | Description     |
+| :-------- | :--- | :-------------- |
+| `value`   | \*   | Value to check. |
+
+**Returns:** boolean — Is the value an extractable file.
+
+#### See
+
+- [`isExtractableFile`](#function-isextractablefile) has this type.
+
+#### Examples
+
+_How to check for the default exactable files, as well as a custom type of file._
+
+> ```js
+> const { isExtractableFile } = require('apollo-upload-client')
+>
+> const isExtractableFileEnhanced = value =>
+>   isExtractableFile(value) ||
+>   (typeof CustomFile !== 'undefined' && value instanceof CustomFile)
+> ```
+
+---
+
 ### type FetchOptions
 
 GraphQL request `fetch` options.
@@ -203,9 +280,26 @@ GraphQL request `fetch` options.
 
 ---
 
+### type FormDataFileAppender
+
+Appends a file extracted from the GraphQL operation to the [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance used as the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch) `options.body` for the [GraphQL multipart request](https://github.com/jaydenseric/graphql-multipart-request-spec).
+
+| Parameter | Type | Description |
+| :-- | :-- | :-- |
+| `formData` | FormData | [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance to append the specified file to. |
+| `fieldName` | string | Field name for the file. |
+| `file` | \* | File to append. The file type depends on what the [`ExtractableFileMatcher`](#type-extractablefilematcher) extracts. |
+
+#### See
+
+- [`formDataAppendFile`](#function-formdataappendfile) has this type.
+- [`createUploadLink`](#function-createuploadlink) accepts this type in `options.formDataAppendFile`.
+
+---
+
 ### type ReactNativeFileSubstitute
 
-A React Native [`File`](https://developer.mozilla.org/docs/web/api/file) substitute.
+A React Native [`File`](https://developer.mozilla.org/en-US/docs/Web/API/File) substitute.
 
 Be aware that inspecting network requests with Chrome dev tools interferes with the React Native `FormData` implementation, causing network errors.
 
@@ -219,7 +313,7 @@ Be aware that inspecting network requests with Chrome dev tools interferes with
 
 #### See
 
-- [`extract-files` docs](https://github.com/jaydenseric/extract-files#type-reactnativefilesubstitute).
+- [`extract-files` `ReactNativeFileSubstitute` docs](https://github.com/jaydenseric/extract-files#type-reactnativefilesubstitute).
 - [React Native `FormData` polyfill source](https://github.com/facebook/react-native/blob/v0.45.1/Libraries/Network/FormData.js#L34).
 
 #### Examples

diff --git a/src/index.js b/src/index.js
@@ -9,18 +9,22 @@ const {
   createSignalIfSupported,
   parseAndCheckHttpResponse
 } = require('apollo-link-http-common')
-const { extractFiles, ReactNativeFile } = require('extract-files')
+const {
+  extractFiles,
+  isExtractableFile,
+  ReactNativeFile
+} = require('extract-files')
 
 /**
- * A React Native [`File`](https://developer.mozilla.org/docs/web/api/file)
+ * A React Native [`File`](https://developer.mozilla.org/en-US/docs/Web/API/File)
  * substitute.
  *
  * Be aware that inspecting network requests with Chrome dev tools interferes
  * with the React Native `FormData` implementation, causing network errors.
  * @kind typedef
  * @name ReactNativeFileSubstitute
  * @type {object}
- * @see [`extract-files` docs](https://github.com/jaydenseric/extract-files#type-reactnativefilesubstitute).
+ * @see [`extract-files` `ReactNativeFileSubstitute` docs](https://github.com/jaydenseric/extract-files#type-reactnativefilesubstitute).
  * @see [React Native `FormData` polyfill source](https://github.com/facebook/react-native/blob/v0.45.1/Libraries/Network/FormData.js#L34).
  * @prop {string} uri Filesystem path.
  * @prop {string} [name] File name.
@@ -36,14 +40,13 @@ const { extractFiles, ReactNativeFile } = require('extract-files')
  */
 
 /**
- * Used to mark a
- * [React Native `File` substitute]{@link ReactNativeFileSubstitute}.
- * It’s too risky to assume all objects with `uri`, `type` and `name` properties
- * are files to extract. Re-exported from [`extract-files`](https://npm.im/extract-files)
- * for convenience.
+ * Used to mark [React Native `File` substitutes]{@link ReactNativeFileSubstitute}
+ * as it’s too risky to assume all objects with `uri`, `type` and `name`
+ * properties are extractable files.
  * @kind class
  * @name ReactNativeFile
- * @param {ReactNativeFileSubstitute} file A React Native [`File`](https://developer.mozilla.org/docs/web/api/file) substitute.
+ * @param {ReactNativeFileSubstitute} file A React Native [`File`](https://developer.mozilla.org/en-US/docs/Web/API/File) substitute.
+ * @see [`extract-files` `ReactNativeFile` docs](https://github.com/jaydenseric/extract-files#class-reactnativefile).
  * @example <caption>A React Native file that can be used in query or mutation variables.</caption>
  * ```js
  * const { ReactNativeFile } = require('apollo-upload-client')
@@ -67,17 +70,90 @@ exports.ReactNativeFile = ReactNativeFile
  * @prop {string} [credentials] Authentication credentials mode.
  */
 
+/**
+ * A function that checks if a value is an extractable file.
+ * @kind typedef
+ * @name ExtractableFileMatcher
+ * @type {Function}
+ * @param {*} value Value to check.
+ * @returns {boolean} Is the value an extractable file.
+ * @see [`isExtractableFile`]{@link isExtractableFile} has this type.
+ * @example <caption>How to check for the default exactable files, as well as a custom type of file.</caption>
+ * ```js
+ * const { isExtractableFile } = require('apollo-upload-client')
+ *
+ * const isExtractableFileEnhanced = value =>
+ *   isExtractableFile(value) ||
+ *   (typeof CustomFile !== 'undefined' && value instanceof CustomFile)
+ * ```
+ */
+
+/**
+ * The default implementation for [`createUploadLink`]{@link createUploadLink}
+ * `options.isExtractableFile`.
+ * @kind function
+ * @name isExtractableFile
+ * @type {ExtractableFileMatcher}
+ * @param {*} value Value to check.
+ * @returns {boolean} Is the value an extractable file.
+ * @see [`extract-files` `isExtractableFile` docs](https://github.com/jaydenseric/extract-files#function-isextractablefile).
+ */
+exports.isExtractableFile = isExtractableFile
+
+/**
+ * Appends a file extracted from the GraphQL operation to the
+ * [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData)
+ * instance used as the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch)
+ * `options.body` for the [GraphQL multipart request](https://github.com/jaydenseric/graphql-multipart-request-spec).
+ * @kind typedef
+ * @name FormDataFileAppender
+ * @param {FormData} formData [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance to append the specified file to.
+ * @param {string} fieldName Field name for the file.
+ * @param {*} file File to append. The file type depends on what the [`ExtractableFileMatcher`]{@link ExtractableFileMatcher} extracts.
+ * @see [`formDataAppendFile`]{@link formDataAppendFile} has this type.
+ * @see [`createUploadLink`]{@link createUploadLink} accepts this type in `options.formDataAppendFile`.
+ */
+
+/**
+ * The default implementation for [`createUploadLink`]{@link createUploadLink}
+ * `options.formDataAppendFile` that uses the standard
+ * [`FormData.append`](https://developer.mozilla.org/en-US/docs/Web/API/FormData/append)
+ * method.
+ * @kind function
+ * @name formDataAppendFile
+ * @type {FormDataFileAppender}
+ * @param {FormData} formData [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance to append the specified file to.
+ * @param {string} fieldName Field name for the file.
+ * @param {*} file File to append.
+ */
+function formDataAppendFile(formData, fieldName, file) {
+  formData.append(fieldName, file, file.name)
+}
+
+exports.formDataAppendFile = formDataAppendFile
+
 /**
  * Creates a terminating [Apollo Link](https://apollographql.com/docs/link)
- * capable of file uploads. Options match [`createHttpLink`](https://apollographql.com/docs/link/links/http#options).
+ * capable of file uploads.
+ *
+ * The link matches and extracts files in the GraphQL operation. If there are
+ * files it uses a [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData)
+ * instance as the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch)
+ * `options.body` to make a [GraphQL multipart request](https://github.com/jaydenseric/graphql-multipart-request-spec),
+ * otherwise it sends a regular POST request.
+ *
+ * Some of the options are similar to the [`createHttpLink` options](https://www.apollographql.com/docs/link/links/http/#options).
  * @see [GraphQL multipart request spec](https://github.com/jaydenseric/graphql-multipart-request-spec).
  * @see [apollo-link on GitHub](https://github.com/apollographql/apollo-link).
  * @kind function
  * @name createUploadLink
  * @param {object} options Options.
  * @param {string} [options.uri=/graphql] GraphQL endpoint URI.
- * @param {Function} [options.fetch] [`fetch`](https://fetch.spec.whatwg.org) implementation to use, defaulting to the `fetch` global.
- * @param {FetchOptions} [options.fetchOptions] `fetch` options; overridden by upload requirements.
+ * @param {ExtractableFileMatcher} [options.isExtractableFile=isExtractableFile] Customizes how files are matched in the GraphQL operation for extraction.
+ * @param {class} [options.FormData] [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) implementation to use, defaulting to the [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) global.
+ * @param {FormDataFileAppender} [options.formDataAppendFile=formDataAppendFile] Customizes how extracted files are appended to the [`FormData`](https://developer.mozilla.org/en-US/docs/Web/API/FormData) instance.
+ * @param {Function} [options.fetch] [`fetch`](https://fetch.spec.whatwg.org) implementation to use, defaulting to the [`fetch`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch) global.
+ * @param {FetchOptions} [options.fetchOptions] [`fetch` options]{@link FetchOptions}; overridden by upload requirements.
  * @param {string} [options.credentials] Overrides `options.fetchOptions.credentials`.
  * @param {object} [options.headers] Merges with and overrides `options.fetchOptions.headers`.
  * @param {boolean} [options.includeExtensions=false] Toggles sending `extensions` fields to the GraphQL server.
@@ -96,7 +172,10 @@ exports.ReactNativeFile = ReactNativeFile
  */
 exports.createUploadLink = ({
   uri: fetchUri = '/graphql',
-  fetch: linkFetch = fetch,
+  isExtractableFile: customIsExtractableFile = isExtractableFile,
+  FormData: CustomFormData = FormData,
+  formDataAppendFile: customFormDataAppendFile = formDataAppendFile,
+  fetch: customFetch = fetch,
   fetchOptions,
   credentials,
   headers,
@@ -141,7 +220,7 @@ exports.createUploadLink = ({
       contextConfig
     )
 
-    const { clone, files } = extractFiles(body)
+    const { clone, files } = extractFiles(body, '', customIsExtractableFile)
     const payload = serializeFetchParameter(clone, 'Payload')
 
     if (files.size) {
@@ -151,7 +230,7 @@ exports.createUploadLink = ({
       // GraphQL multipart request spec:
       // https://github.com/jaydenseric/graphql-multipart-request-spec
 
-      const form = new FormData()
+      const form = new CustomFormData()
 
       form.append('operations', payload)
 
@@ -164,7 +243,7 @@ exports.createUploadLink = ({
 
       i = 0
       files.forEach((paths, file) => {
-        form.append(++i, file, file.name)
+        customFormDataAppendFile(form, ++i, file)
       })
 
       options.body = form
@@ -183,7 +262,7 @@ exports.createUploadLink = ({
         }
       }
 
-      linkFetch(uri, options)
+      customFetch(uri, options)
         .then(response => {
           // Forward the response on the context.
           operation.setContext({ response })