Planned lessonJNR-029-L02

Derived queries

Lesson 2 of 7
Junior

On This Lesson 4 topics

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Planned topics
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This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.

In this lesson

write queries from method names, and know when to stop.

Planned topics

Spring parses names like findByNameContainingIgnoreCase into JPQL.
Keywords: And, Or, Between, LessThan, OrderBy, Containing, IsNull.
Great for one or two conditions.
When the name grows past about 3 conditions, it is hard to read: switch to @Query.
Typos in property names fail at startup, which is a useful early warning.

Draft outline details

Demonstration

java

List<Product> findByCategoryIdAndPriceAmountLessThanOrderByNameAsc(Long categoryId, BigDecimal max); // too long
Optional<Product> findBySku(String sku);                                                             // good

Check your understanding

When should you replace a derived query with @Query?

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When the name becomes hard to read, around three or more conditions.

Practice

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