Support Metadata in GridFSAdapter (#6660)

* Support Metadata in GridFSAdapter

* Useful for testing in the JS SDK
* Adds new endpoint to be used with `Parse.File.getData`
* Allows file adapters to return tags as well as future data.

* fix tests

* Make getMetadata optional

* Revert "fix tests"

This reverts commit 7706da13c688027483974e854b5b24321fb070cd.

* improve coverage

src/Adapters/Files/GridFSBucketAdapter.js

@@ -32,7 +32,7 @@ export class GridFSBucketAdapter extends FilesAdapter {
       this._connectionPromise = MongoClient.connect(
         this._databaseURI,
         this._mongoOptions
-      ).then(client => {
+      ).then((client) => {
         this._client = client;
         return client.db(client.s.options.dbName);
       });
@@ -41,14 +41,16 @@ export class GridFSBucketAdapter extends FilesAdapter {
   }
 
   _getBucket() {
-    return this._connect().then(database => new GridFSBucket(database));
+    return this._connect().then((database) => new GridFSBucket(database));
   }
 
   // For a given config object, filename, and data, store a file
   // Returns a promise
-  async createFile(filename: string, data) {
+  async createFile(filename: string, data, contentType, options = {}) {
     const bucket = await this._getBucket();
-    const stream = await bucket.openUploadStream(filename);
+    const stream = await bucket.openUploadStream(filename, {
+      metadata: options.metadata,
+    });
     await stream.write(data);
     stream.end();
     return new Promise((resolve, reject) => {
@@ -64,7 +66,7 @@ export class GridFSBucketAdapter extends FilesAdapter {
       throw new Error('FileNotFound');
     }
     return Promise.all(
-      documents.map(doc => {
+      documents.map((doc) => {
         return bucket.delete(doc._id);
       })
     );
@@ -76,13 +78,13 @@ export class GridFSBucketAdapter extends FilesAdapter {
     stream.read();
     return new Promise((resolve, reject) => {
       const chunks = [];
-      stream.on('data', data => {
+      stream.on('data', (data) => {
         chunks.push(data);
       });
       stream.on('end', () => {
         resolve(Buffer.concat(chunks));
       });
-      stream.on('error', err => {
+      stream.on('error', (err) => {
         reject(err);
       });
     });
@@ -98,6 +100,16 @@ export class GridFSBucketAdapter extends FilesAdapter {
     );
   }
 
+  async getMetadata(filename) {
+    const bucket = await this._getBucket();
+    const files = await bucket.find({ filename }).toArray();
+    if (files.length === 0) {
+      return {};
+    }
+    const { metadata } = files[0];
+    return { metadata };
+  }
+
   async handleFileStream(filename: string, req, res, contentType) {
     const bucket = await this._getBucket();
     const files = await bucket.find({ filename }).toArray();
@@ -122,7 +134,7 @@ export class GridFSBucketAdapter extends FilesAdapter {
     });
     const stream = bucket.openDownloadStreamByName(filename);
     stream.start(start);
-    stream.on('data', chunk => {
+    stream.on('data', (chunk) => {
       res.write(chunk);
     });
     stream.on('error', () => {