Parse: count of objects with pointer to another type object with given ID

Question

I have defined a Parse core object of type X that has a pointer to another object of type Y as one of its attributes. There are about 1000 of type X objects defined and about 20 of type Y objects.

I need to create a JavaScript query that would start with object ID for a type Y object and get count of type X objects that contain pointer to a type Y object with this object ID.

This would be a very easy query against a traditional SQL-based back-end, but in Parse I can't find a solution.

Sandra · Accepted Answer · 2015-12-02 15:06:43Z

1

You can easily do this using a relational query. Lets assume you have a local instance of an object of class Y, then the query would look like this

var ObjectX = Parse.Object.extend("X");
var query = new Parse.Query(ObjectX);
query.equalTo("objectYField", myObjectOfTypeY);
query.count({
  success: function(count) {
    // The count request succeeded. Show the count
  },
  error: function(error) {
    // The request failed
  }
});

One small caveat from the docs though

Count queries are rate limited to a maximum of 160 requests per minute. They can also return inaccurate results for classes with more than 1,000 objects. Thus, it is preferable to architect your application to avoid this sort of count operation (by using counters, for example.)

edited Dec 2, 2015 at 15:06

Sandra

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answered Jun 29, 2015 at 16:16

Björn Kaiser

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2 Comments

Alexandre Efremov Over a year ago

This query starts with the myObjectOfTypeY. In my case, I start with the objectId of myObjectOfTypeY, not the whole object.

Björn Kaiser Over a year ago

If you just have the ID, you should be able to create an empty object of that type, set the ID and pass it in for objectYField (see parse.com/docs/js/api/symbols/…)

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