Cleanup

node_modules/mongodb/lib/operations/distinct.js

@@ -5,6 +5,8 @@ const defineAspects = require('./operation').defineAspects;
 const CommandOperationV2 = require('./command_v2');
 const decorateWithCollation = require('../utils').decorateWithCollation;
 const decorateWithReadConcern = require('../utils').decorateWithReadConcern;
+const maxWireVersion = require('../core/utils').maxWireVersion;
+const MongoError = require('../error').MongoError;
 
 /**
  * Return a list of distinct values for the given key across a collection.
@@ -65,13 +67,18 @@ class DistinctOperation extends CommandOperationV2 {
       return callback(err, null);
     }
 
+    if (this.explain && maxWireVersion(server) < 4) {
+      callback(new MongoError(`server does not support explain on distinct`));
+      return;
+    }
+
     super.executeCommand(server, cmd, (err, result) => {
       if (err) {
         callback(err);
         return;
       }
 
-      callback(null, this.options.full ? result : result.values);
+      callback(null, this.options.full || this.explain ? result : result.values);
     });
   }
 }
@@ -79,7 +86,8 @@ class DistinctOperation extends CommandOperationV2 {
 defineAspects(DistinctOperation, [
   Aspect.READ_OPERATION,
   Aspect.RETRYABLE,
-  Aspect.EXECUTE_WITH_SELECTION
+  Aspect.EXECUTE_WITH_SELECTION,
+  Aspect.EXPLAINABLE
 ]);
 
 module.exports = DistinctOperation;