Synthetic constructors should not be considered persistence constructors [DATACMNS-1082]

[spring-projects-issues]

Roman Rodov opened DATACMNS-1082 and commented

As the title says Synthetic Constructors Should not be considered by org.springframework.data.mapping.model.PreferredConstructorDiscoverer as it is also common for them not to have correct parameter names to map to fields.

Exmaple, in Kotlin combined with Spring Data Mongo

The following class (just a dumbed down example):

@Document
data class Address @PersistenceConstructor constructor(
    val postcode: String,
    val state: String,
    var streetAddress: StreetAddress? = null
)

Will cause Kotlin to generate 2 constructors (because of the use of "default" parameter:

@PersistenceConstructor public Address(String postcode,String state,StreetAddress streetAddress) { ... }

and

@PersistenceConstructor public /* synthetic */ Address(String arg0, String arg1, StreetAddress arg2, int arg3, DefaultConstructorMarker arg4) { ... }

PreferredConstructorDiscoverer in random order (sometimes it will, sometimes it won't, due to order of the constructors in bytecode) will pick the synthetic constructor which will cause a MappingException with message: No property null found on entity Address to bind constructor parameter to! Notice the null value. That is because the synthetic constructor does not have parameter meta data.

I have a PR ready, which is super simple I guess

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Affects: 2.0 M3 (Kay), 1.13.3 (Ingalls SR3)

Referenced from: pull request #225

Backported to: 1.13.4 (Ingalls SR4), 1.12.11 (Hopper SR11)