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Lopakhin
Lopakhin

Reputation: 299

How to select partial fields from collection which is of one-to-many relation to the entity in JPQL

The question is quite mouthful , it can be simply described by the following query:

select c.name,c.brands FROM ShopChannels c

ShopChannel is the basic entity which has a collection of brands which is of on-to-many,instead select all the brand properties in this query ,I only want to select partial fields of Brand, if I use

select c.name,c.brands.spell from ShopChannels c

I'll get a "cannot navigate collection valued association field " error message.

This kind of query can greatly boost performance, so anyone has an idea?

Upvotes: 0

Views: 1781

Answers (1)

remigio
remigio

Reputation: 4211

The JPA specification says that "´It is syntactically illegal to compose a path expression from a path expression that evaluates to a collection.´" A solution to your need is a join query like: ´select c.name,b.spell from ShopChannels c inner join c.brands b´.

Upvotes: 2

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