node.js - Mongoose find all documents with a given ObjectId -

I have a photo model and each picture has a vehicle associated with it:

  Var object id = mongoose Sema Object ID; Var photoSchema = mongoose.Schema ({name: {type: string}, path: {type: string}, vehicle: {type: object, ref: 'vehicle'}});   
 What can I do to return all the photos matching the given vehicle  _id ? I think the query looks like a normal search, but I'm not sure how to convert  _id  into an  ObjectId.    
 
 
 You do not have to change anything, your  ObjectId  The same is  _id  but in the  string  format when you send it anywhere via JSON try the following:  
  Photo.find ({Vehicle: id}, function (fault, result) {...});   
 above  id  is just your  vehicle  's