feat(collection): add colleciton level document mapping/unmapping

lib/collection.js

@@ -378,14 +378,14 @@ Collection.prototype.find = function(query, options, callback) {
   // Decorate find command with collation options
   decorateWithCollation(findCommand, this, options);
 
-  // Create the cursor
-  if (typeof callback === 'function')
-    return handleCallback(
-      callback,
-      null,
-      this.s.topology.cursor(this.s.namespace, findCommand, newOptions)
-    );
-  return this.s.topology.cursor(this.s.namespace, findCommand, newOptions);
+  const cursor = this.s.topology.cursor(this.s.namespace, findCommand, newOptions);
+
+  // automatically call map on the cursor if the map option is set
+  if (typeof this.s.options.map === 'function') {
+    cursor.map(this.s.options.map);
+  }
+
+  return typeof callback === 'function' ? handleCallback(callback, null, cursor) : cursor;
 };
 
 /**
@@ -491,19 +491,7 @@ Collection.prototype.insertMany = function(docs, options, callback) {
   // If keep going set unordered
   options['serializeFunctions'] = options['serializeFunctions'] || self.s.serializeFunctions;
 
-  // Set up the force server object id
-  var forceServerObjectId =
-    typeof options.forceServerObjectId === 'boolean'
-      ? options.forceServerObjectId
-      : self.s.db.options.forceServerObjectId;
-
-  // Do we want to force the server to assign the _id key
-  if (forceServerObjectId !== true) {
-    // Add _id if not specified
-    for (var i = 0; i < docs.length; i++) {
-      if (docs[i]._id == null) docs[i]._id = self.s.pkFactory.createPk();
-    }
-  }
+  docs = prepareDocs(this, docs, options);
 
   // Generate the bulk write operations
   var operations = [
@@ -683,18 +671,7 @@ var insertDocuments = function(self, docs, options, callback) {
   if (finalOptions.keepGoing === true) finalOptions.ordered = false;
   finalOptions['serializeFunctions'] = options['serializeFunctions'] || self.s.serializeFunctions;
 
-  // Set up the force server object id
-  var forceServerObjectId =
-    typeof options.forceServerObjectId === 'boolean'
-      ? options.forceServerObjectId
-      : self.s.db.options.forceServerObjectId;
-
-  // Add _id if not specified
-  if (forceServerObjectId !== true) {
-    for (var i = 0; i < docs.length; i++) {
-      if (docs[i]._id === void 0) docs[i]._id = self.s.pkFactory.createPk();
-    }
-  }
+  docs = prepareDocs(self, docs, options);
 
   // File inserts
   self.s.topology.insert(self.s.namespace, docs, finalOptions, function(err, result) {
@@ -909,6 +886,10 @@ Collection.prototype.replaceOne = function(filter, doc, options, callback) {
     options.ignoreUndefined = this.s.options.ignoreUndefined;
   }
 
+  if (typeof this.s.options.unmap === 'function') {
+    doc = this.s.options.unmap(doc);
+  }
+
   return executeOperation(this.s.topology, replaceOne, [this, filter, doc, options, callback]);
 };
 
@@ -2253,6 +2234,11 @@ var findAndModify = function(self, query, sort, doc, options, callback) {
   // Execute the command
   self.s.db.command(queryObject, finalOptions, function(err, result) {
     if (err) return handleCallback(callback, err, null);
+
+    if (result && result.value && typeof self.s.options.map === 'function') {
+      result.value = self.s.options.map(result.value);
+    }
+
     return handleCallback(callback, null, result);
   });
 };
@@ -3028,4 +3014,28 @@ var getReadPreference = function(self, options, db) {
   return options;
 };
 
+// modifies documents before being inserted or updated
+const prepareDocs = function(self, docs, options) {
+  const forceServerObjectId =
+    typeof options.forceServerObjectId === 'boolean'
+      ? options.forceServerObjectId
+      : self.s.db.options.forceServerObjectId;
+
+  const unmap = typeof self.s.options.unmap === 'function' ? self.s.options.unmap : false;
+
+  // no need to modify the docs if server sets the ObjectId
+  // and unmap collection option is unset
+  if (forceServerObjectId === true && !unmap) {
+    return docs;
+  }
+
+  return docs.map(function(doc) {
+    if (forceServerObjectId !== true && doc._id == null) {
+      doc._id = self.s.pkFactory.createPk();
+    }
+
+    return unmap ? unmap(doc) : doc;
+  });
+};
+
 module.exports = Collection;

lib/db.js

@@ -400,6 +400,8 @@ var collectionKeys = [
  * @param {(ReadPreference|string)} [options.readPreference=null] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
  * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
  * @param {boolean} [options.strict=false] Returns an error if the collection does not exist
+ * @param {function} [options.map] Function to map documents returned in find, findOne, and findAndModify commands.
+ * @param {function} [options.unmap] Function to unmap documents passed to insertOne, insertMany, and replaceOne commands.
  * @param {object} [options.readConcern=null] Specify a read concern for the collection. (only MongoDB 3.2 or higher supported)
  * @param {object} [options.readConcern.level='local'] Specify a read concern level for the collection operations, one of [local|majority]. (only MongoDB 3.2 or higher supported)
  * @param {Db~collectionResultCallback} [callback] The collection result callback