SpEL template behavior is inconsistent [DATAJPA-1266]

[spring-projects-issues]

Jens Schauder opened DATAJPA-1266 and commented

The following tests succeed when added to ExpressionBasedStringQueryUnitTests

	@Test
	public void doesTemplatingWhenEntityNameSpelIsPresent() {

		StringQuery query = new ExpressionBasedStringQuery("select #{#entityName + 'Hallo'} from #{#entityName} u", metadata, SPEL_PARSER);

		assertThat(query.getQueryString(), is("select UserHallo from User u"));
	}

	@Test
	public void doesNotTemplatingWhenEntityNameSpelIsNotPresent() {

		StringQuery query = new ExpressionBasedStringQuery("select #{#entityName + 'Hallo'} from User u", metadata, SPEL_PARSER);

		assertThat(query.getQueryString(), is("select #{#entityName + 'Hallo'} from User u"));
	}

	@Test
	public void doesTemplatingWhenEntityNameSpelIsPresentForBindParameter() {

		StringQuery query = new ExpressionBasedStringQuery("select u from #{#entityName} u where name = :#{#something}", metadata, SPEL_PARSER);

		assertThat(query.getQueryString(), is("select u from User u where name = :"));
	}

We only apply templating if #\{#entityName\} is present in the query string. If we do so, we use the full-blown SpEL templating mechanism, i.e also other SpEL expressions get evaluated and replaced.

Also, SpEL expressions for bind parameters only get protected from this when they start with ?# not when they start with :#

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No further details from DATAJPA-1266

[spring-projects-issues]

Oliver Drotbohm commented

I guess we need to:

1. Replace bind variables using the API to be created, so that an intermediate query string can be produced with the SpEL-based bind variables replaced by synthetic placeholders and the expressions externalized for standalone evaluation.
2. Replace all remaining SpEL expressions evaluated eagerly.

If we can trigger 2 without masking the SpEL-based bind variables to be handled in 1, we can also flip the steps, should that make things easier

[gregturn]

I have re-input @schauder 's original test cases and run them through the latest-and-greatest of Spring Data JPA, parser and all. Can either @schauder or @odrotbohm verify that this is the desired final results? If so, I'll add these test cases and push to main.

@Test
public void doesTemplatingWhenEntityNameSpelIsPresent() {

	StringQuery query = new ExpressionBasedStringQuery("select #{#entityName + 'Hallo'} from #{#entityName} u",
			metadata, SPEL_PARSER, false);

	assertThat(query.getQueryString()).isEqualTo("select UserHallo from User u");
}

@Test
public void doesNoTemplatingWhenEntityNameSpelIsNotPresent() {

	StringQuery query = new ExpressionBasedStringQuery("select #{#entityName + 'Hallo'} from User u", metadata,
			SPEL_PARSER, false);

	assertThat(query.getQueryString()).isEqualTo("select #{#entityName + 'Hallo'} from User u");
}

@Test
public void doesTemplatingWhenEntityNameSpelIsPresentForBindParameter() {

	StringQuery query = new ExpressionBasedStringQuery("select u from #{#entityName} u where name = :#{#something}",
			metadata, SPEL_PARSER, false);

	assertThat(query.getQueryString()).isEqualTo("select u from User u where name = :__$synthetic$__1");
}

[schauder]

I think the second should be select UserHallo from User u

[gregturn]

Merged to main. Backported to 3.1.x.