Nested Queries in Parse cloud code

Question

I'm confused how to use parses cloud code to perform a nested query or relational query.

What I want to do is get all objectId's from table1 that match a criteria.

Then use those objectId's to query table2 and check for query2.equalTo("table2ID", table1[i].objectId);

Then get the count of all object's that match that query2 and if < X return table1[i].

danh · Accepted Answer · 2018-02-05 16:10:48Z

Since you really want to count members of table2, make that your main query...

var query = new Parse.Query("Table2");

The thing you want to count is table2 elements that are associated with table1 elements such that the table1 element matches some criterion...

var innerQuery = new Parse.Query("Table1");
innerQuery.equalTo("someKey", "someValue");  // some criterion
query.matchesQuery("table2ID", innerQuery);

Now, get a count....

query.count().then(count => /* do something if count > X? */);

It's important that the data is setup properly for this:

When initializing table2 elements, you need to place real references to table1 objects (not just strings representing ids).

myTable1Object = // whatever
myTable2Object.set("table2ID", myTable1Object.id);  // WRONG
myTable2Object.set("table2ID", myTable1Object);     // correct

I think the made-up names you used in your question might also add some confusion. A real pointer to table1 is better called "table1". That is, not table2 (which is the table where it appears) and no "ID" suffix which implies it violates point #1 above.

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