CODEWITHSUNDEEP
objective-ccore-data
subharb
subharb

Reputation: 3472

Using SUBQUERY with multiple attributes

I have 3 entities, "Bar", "Waiter", "Product" the relationship is as follows, A "Bar" has one to many relationship with "Waiter" and the same from Waiter to Product.

I need to know which Bars has been serving Products with certain attributes.

The entity Im fetching is Bars, So far I've tried:

[NSPredicate predicateWithFormat:@"SUBQUERY(toWaiter, $x, ANY $x.toProduct.dateServed > %@ AND $x.toProduct.dateConsumed > %@).@count > 0), [NSDate date], [NSDate date]];

Where I get

Only allowed one toMany/manyToMany relationship in subquery expression collection

If I try:

[NSPredicate predicateWithFormat:@"SUBQUERY(toWaiter, $x, ANY $x.toProduct.dateServed > %@ ANY AND $x.toProduct.dateConsumed > %@).@count > 0), [NSDate date], [NSDate date]];

Two ANYs, I get the same error,

Only allowed one toMany/manyToMany relationship in subquery expression collection

Which is the correct way to subquery for more than one attribute?

thanks.

This is the model: enter image description here

Upvotes: 0

Views: 268

Answers (1)

pbasdf
pbasdf

Reputation: 21536

You can do this by nesting two SUBQUERY clauses together:

NSPredicate *filter = [NSPredicate predicateWithFormat:@"SUBQUERY(toWaiter, $x, SUBQUERY($x.toProduct, $y, $y.dateServed > %@ AND $y.dateConsumed > %@).@count > 0).@count > 0", [NSDate date], [NSDate date]];

Or, in (vaguely) natural language: "fetch all the Bars with a non-zero count of (Waiters with a non-zero count of (Products with both dateServed and dateConsumed greater than today))".

Upvotes: 2

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