From 28ae1e8ee65689201cc910af0d44c0924ca62b13 Mon Sep 17 00:00:00 2001
From: Maik Marschner <an@maik.tk>
Date: Fri, 6 May 2016 19:56:57 +0200
Subject: [PATCH] Add a function to update a file's metadata.

---
 lib/index.js | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/lib/index.js b/lib/index.js
index a892c55..fe8466a 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -144,6 +144,41 @@ Grid.prototype.findOne = function (options, callback) {
   });
 }
 
+/**
+ * Update the metadata of the file matched by passing any options, at least an _id or filename
+ *
+ * @param {Object} options
+ * @param {Object} metadata
+ * @param {Function} callback
+ */
+
+Grid.prototype.updateMetadata = function (options, metadata, callback) {
+  if ('function' != typeof callback) {
+    throw new Error('updateMetadata requires a callback function');
+  }
+  var find = {};
+  for (var n in options) {
+    if (n != 'root') {
+      find[n] = options[n];
+    }
+  }
+  if (find._id) {
+    find._id = this.tryParseObjectId(find._id) || find._id;
+  }
+  var collection = options.root  && options.root != this.curCol ? this.db.collection(options.root + ".files") : this.files;
+  if (!collection) {
+    return callback(new Error('No collection specified'));
+  }
+  var newMetadata = {}
+  for (var m in metadata) {
+    newMetadata['metadata.' + m] = metadata[m]
+  }
+  collection.update(find, { $set: newMetadata }, function(err) {
+    if (err) { return callback(err); }
+    callback(null);
+  });
+}
+
 /**
  * Attemps to parse `string` into an ObjectId
  *