Mongoose casting issue when using two fields in a where clause

Question

Mongoose casting issue when using two fields in a where clause

I'm still trying to wrap my head around mongoDB/mongoose and haven't been able to workout what's wrong with the below query;

Link
  .find()
  .where('active').equals(true)
  .where('access_count').gt(0).lte('access_limit')
  .limit(5)
  .sort('-created')
  .exec(function(err,latest)

Which returns the below cast error;

CastError: Cast to number failed for value "access_limit" at path "access_count"
at SchemaNumber.cast

This is caused by the .where('access_count').gt(0).lte('access_limit') I assume it's due to the comparison of two fields on the document? Is there a correct way of doing this and any advice for debugging these kind of issues?

For reference the schema is defined as;

var LinkSchema = new Schema({
 token: {type: String, unique: true, index: true, required: true }
 , title: {type: String}
 , url: {type: String, required: true}
 , active: {type: Boolean, default: true}
 , created: {type: Date, default: Date.now}
 , access_count: {type: Number, default: 0}
 , access_expiry: Date
 , access_limit: {type: Number, default: 0}
})

javascript
node.js
mongodb
mongoose

Answer 1

To compare one field against another in a query, you have to use a $where clause:

Link
  .find()
  .where('active').equals(true)
  .where('access_count').gt(0)
  .$where('this.access_count <= this.access_limit')
  .limit(5)
  .sort('-created')
  .exec(function(err,latest)

$where can be slow, so do as much as possible with normal where clauses to reduce the number of docs that $where needs to execute over.