Cleanup

node_modules/mongodb/lib/operations/map_reduce.js

@@ -9,10 +9,16 @@ const handleCallback = require('../utils').handleCallback;
 const isObject = require('../utils').isObject;
 const loadDb = require('../dynamic_loaders').loadDb;
 const OperationBase = require('./operation').OperationBase;
-const resolveReadPreference = require('../utils').resolveReadPreference;
+const ReadPreference = require('../core').ReadPreference;
 const toError = require('../utils').toError;
+const Aspect = require('./operation').Aspect;
+const defineAspects = require('./operation').defineAspects;
+const decorateWithExplain = require('../utils').decorateWithExplain;
+const maxWireVersion = require('../core/utils').maxWireVersion;
+const MongoError = require('../error').MongoError;
 
 const exclusionList = [
+  'explain',
   'readPreference',
   'session',
   'bypassDocumentValidation',
@@ -59,8 +65,8 @@ class MapReduceOperation extends OperationBase {
     const reduce = this.reduce;
     let options = this.options;
 
-    const mapCommandHash = {
-      mapreduce: coll.collectionName,
+    let mapCommandHash = {
+      mapReduce: coll.collectionName,
       map: map,
       reduce: reduce
     };
@@ -80,7 +86,7 @@ class MapReduceOperation extends OperationBase {
     options = Object.assign({}, options);
 
     // Ensure we have the right read preference inheritance
-    options.readPreference = resolveReadPreference(coll, options);
+    options.readPreference = ReadPreference.resolve(coll, options);
 
     // If we have a read preference and inline is not set as output fail hard
     if (
@@ -110,6 +116,14 @@ class MapReduceOperation extends OperationBase {
       return callback(err, null);
     }
 
+    if (this.explain) {
+      if (maxWireVersion(coll.s.topology) < 9) {
+        callback(new MongoError(`server does not support explain on mapReduce`));
+        return;
+      }
+      mapCommandHash = decorateWithExplain(mapCommandHash, this.explain);
+    }
+
     // Execute command
     executeCommand(coll.s.db, mapCommandHash, options, (err, result) => {
       if (err) return handleCallback(callback, err);
@@ -118,6 +132,9 @@ class MapReduceOperation extends OperationBase {
         return handleCallback(callback, toError(result));
       }
 
+      // If an explain operation was executed, don't process the server results
+      if (this.explain) return callback(undefined, result);
+
       // Create statistics value
       const stats = {};
       if (result.timeMillis) stats['processtime'] = result.timeMillis;
@@ -187,4 +204,6 @@ function processScope(scope) {
   return new_scope;
 }
 
+defineAspects(MapReduceOperation, [Aspect.EXPLAINABLE]);
+
 module.exports = MapReduceOperation;