Only apply autoconfiguration that injects DataSource by type, if there is a single or primary DataSource #12914
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spring-projects-issues
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the
status: waiting-for-triage
spencergibb
reviewed
Apr 18, 2018
| @@ -49,6 +50,7 @@ | |||
| */ | |||
| @Configuration | |||
| @ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class }) | |||
| @ConditionalOnSingleCandidate(DataSource.class) | |||
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Not sure this makes sense as a few lines later there is @ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) which will now never happen.
|
@rupert654 I disagree with the analysis and we can't accept such change without additional tests that demonstrate and exercise the conditions you've added. Please open a separate issue with a sample that we can run that demonstrates the problem you're experiencing. |
snicoll
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status: declined
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Currently, an error is thrown if I add multiple
DataSources to my context.There are two workarounds for this issue:
DataSources as@PrimaryDataSourceby typeIt is easy to do 1. but this can be arbitrary decision unless the user knows exactly what auto-configuration is being applied. It can lead to subtle differences in behaviour which can trip you up, especially if you don't understand what you are doing by choosing this option.
It is hard to do 2. without a full knowledge of which auto-configurations. A piece of auto-configuration knows if it wants to inject by type and can foresee that injecting a
DataSourceby type is likely to trip people up. Therefore, they should make use ofConditionalOnSingleCandidateso they don't trip anybody up. Afterall, if somebody has already added multiple DataSources without into their application, then they probably know what they want to do with them.This was proposed in #5541 but the commit that closed that ticket did not actually add this annotation to either
DataSourceAutoConfigurationnorDataSourceTransactionManagerAutoConfigurationso this PR fixes that and also updates the documentation to reflect this behaviour.